A police officer holds back other policemen as some demonstrators do the same with their side after a contact during an anti-G7 rally near the venue of the G7 summit in the Sicilian town of Taormina, Italy, Saturday, May 27, 2017. (AP Photo/Gregorio Borgia)


WASHINGTON -- Earth is likely to reach more dangerous levels of warming even sooner if the U.S. retreats from its pledge to cut carbon dioxide pollution, scientists said. That's because America contributes so much to rising temperatures.

President Donald Trump, who once proclaimed global warming a Chinese hoax, said in a tweet Saturday that he would make his "final decision" this coming week on whether the United States stays in or leaves the 2015 Paris climate change accord in which nearly every nation agreed to curb its greenhouse gas emissions.

Leaders of seven wealthy democracies, at a summit in Sicily, urged Trump to commit his administration to the agreement, but said in their closing statement that the U.S., for now, "is not in a position to join the consensus."

"I hope they decide in the right way," said Italy's prime minister, Paolo Gentiloni. More downbeat was German Chancellor Angela Merkel, who said the leaders' talks were "very difficult, if not to say, very unsatisfactory."

In an attempt to understand what could happen to the planet if the U.S. pulls out of Paris, The Associated Press consulted with more than two dozen climate scientists and analyzed a special computer model scenario designed to calculate potential effects.

Scientists said it would worsen an already bad problem and make it far more difficult to prevent crossing a dangerous global temperature threshold.

Calculations suggest it could result in emissions of up to 3 billion tons of additional carbon dioxide in the air a year. When it adds up year after year, scientists said that is enough to melt ice sheets faster, raise seas higher and trigger more extreme weather.

"If we lag, the noose tightens," said Princeton University climate scientist Michael Oppenheimer, co-editor of the peer-reviewed journal Climatic Change.

One expert group ran a worst-case computer simulation of what would happen if the U.S. does not curb emissions, but other nations do meet their targets. It found that America would add as much as half a degree of warming (0.3 degrees Celsius) to the globe by the end of century.

Scientists are split on how reasonable and likely that scenario is.

Many said because of cheap natural gas that displaces coal and growing adoption of renewable energy sources, it is unlikely that the U.S. would stop reducing its carbon pollution even if it abandoned the accord, so the effect would likely be smaller.

Others say it could be worse because other countries might follow a U.S. exit, leading to more emissions from both the U.S. and the rest.

Another computer simulation team put the effect of the U.S. pulling out somewhere between 0.1 to 0.2 degrees Celsius (0.18 to 0.36 degrees Fahrenheit).

While scientists may disagree on the computer simulations they overwhelmingly agreed that the warming the planet is undergoing now would be faster and more intense.

The world without U.S. efforts would have a far more difficult time avoiding a dangerous threshold: keeping the planet from warming more than 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels.

The world has already warmed by just over half that amount - with about one-fifth of the past heat-trapping carbon dioxide emissions coming from the United States, usually from the burning of coal, oil and gas.

So the efforts are really about preventing another 1.6 degrees Fahrenheit (0.9 degrees Celsius) from now.

"Developed nations - particularly the U.S. and Europe - are responsible for the lion's share of past emissions, with China now playing a major role," said Rutgers University climate scientist Jennifer Francis. "This means Americans have caused a large fraction of the warming."

Even with the U.S. doing what it promised under the Paris agreement, the world is likely to pass that 2 degree mark, many scientists said.

But the fractions of additional degrees that the U.S. would contribute could mean passing the threshold faster, which could in turn mean "ecosystems being out of whack with the climate, trouble farming current crops and increasing shortages of food and water," said the National Center for Atmospheric Research's Kevin Trenberth.

Climate Interactive, a team of scientists and computer modelers who track global emissions and pledges, simulated global emissions if every country but the U.S. reaches their individualized goals to curb carbon pollution. Then they calculated what that would mean in global temperature, sea level rise and ocean acidification using scientifically-accepted computer models.

By 2030, it would mean an extra 3 billion tons of carbon dioxide in the air a year, according to the Climate Interactive models, and by the end of the century 0.3 degrees Celsius of warming.

"The U.S. matters a great deal," said Climate Interactive co-director Andrew Jones. "That amount could make the difference between meeting the Paris limit of two degrees and missing it."

Climate Action Tracker, a competing computer simulation team, put the effect of the U.S. pulling out somewhere between 0.1 to 0.2 degrees Celsius (0.18 to 0.36 Fahrenheit) by 2100. It uses a scenario where U.S. emissions flatten through the century, while Climate Interactive has them rising.

One of the few scientists who plays down the harm of the U.S. possibly leaving the agreement is John Schellnhuber, the director of the Potsdam Institute for Climate Impact Research and the scientist credited with coming up with the 2 degree goal.

"Ten years ago (a U.S. exit) would have shocked the planet," Schellnhuber said. "Today if the U.S. really chooses to leave the Paris agreement, the world will move on with building a clean and secure future."

Not so, said Texas Tech climate scientist Katharine Hayhoe: "There will be ripple effects from the United States' choices across the world."

 Source: This article was published on ctvnews.ca by Seth Borenstein, The Associated Press

Categorized in Others

If you could travel back in time 41,000 years to the last ice age, your compass would point south instead of north. That’s because for a period of a few hundred years, the Earth’s magnetic field was reversed. These reversals have happpened repeatedly over the planet’s history, sometimes lasting hundreds of thousands of years. We know this from the way it affects the formation of magnetic minerals, that we can now study on the Earth’s surface.

Several ideas exist to explain why magnetic field reversals happen. One of thesejust became more plausible. My colleagues and I discovered that regions on top of the Earth’s core could behave like giant lava lamps, with blobs of rock periodically rising and falling deep inside our planet. This could affect its magnetic field and cause it to flip. The way we made this discovery was by studying signals from some of the world’s most destructive earthquakes.

Supercomputer models of Earth's magnetic field.NASA

Around 3,000km (1,900 miles) below our feet—270 times further down than the deepest part of the ocean—is the start of the Earth’s core, a liquid sphere of mostly molten iron and nickel. At this boundary between the core and the rocky mantle above, the temperature is almost 4,000 degrees Celsius (7,200 degrees Fahrenheit), similar to that on the surface of a star, with a pressure more than 1.3 million times that at the Earth’s surface.

On the mantle side of this boundary, solid rock gradually flows over millions of years, driving the plate tectonics that cause continents to move and change shape. On the core side, fluid, magnetic iron swirls vigorously, creating and sustaining the Earth’s magnetic field that protects the planet from the radiation of space that would otherwise strip away our atmosphere.

Because it is so far underground, the main way we can study the core-mantle boundary is by looking at the seismic signals generated by earthquakes. Using information about the shape and speed of seismic waves, we can work out what the part of the planet they have travelled through to reach us is like. After a particularly large earthquake, the whole planet vibrates like a ringing bell, and measuring these oscillations in different places can tell us how the structure varies within the planet.

nasa earth interiorNasa image showing Earth's interior. Scientists propose the core acts as a giant lava lamp, influencing the planet's magnetic field.

DIXON ROHR/NASA

In this way, we know there are two large regions at the top of the core where seismic waves travel more slowly than in surrounding areas. Each region is so large that it would be 100 times taller than Mount Everest if it were on the surface of the planet. These regions, termed large-low-velocity-provinces or more often just "blobs," have a significant impact on the dynamics of the mantle. They also influence how the core cools, which alters the flow in the outer core.

Several particularly destructive earthquakes over recent decades have enabled us to measure a special kind of seismic oscillations that travel along the core-mantle boundary, known as Stoneley modesOur most recent research on these modes shows that the two blobs on top of the core have a lower density compared to the surrounding material. This suggests that material is actively rising up towards the surface, consistent with other geophysical observations.

New explanation

Aurora BorealisAurora Borealis from space. Aurorae are caused by the interaction of particles in the solar wind with Earth's magnetic field.

PRINT COLLECTOR/GETTY IMAGES

These regions might be less dense simply because they are hotter. But an exciting alternative possibility is that the chemical composition of these parts of the mantle cause them to behave like the blobs in a lava lamp. This would mean they heat up and periodically rise towards the surface, before cooling and splashing back down on the core.

    Such behaviour would change the way in which heat is extracted from the core’s surface over millions of years. And this could explain why the Earth’s magnetic field sometimes reverses. The fact that the field has changed so many times in the Earth’s history suggests that the internal structure we know today may also have changed.

    We know the core is covered with a landscape of mountains and valleys like the Earth’s surface. By using more data from Earth oscillations to study this topography, we will be able to produce more detailed maps of the core that will give us a much better understanding of what is going on deep below our feet.

    Paula Koelemeijer is a Postdoctoral Fellow in Global Seismology at the University of Oxford

    This article was originally published on The Conversation. Read the original article.

    Categorized in Science & Tech

    Why do the other planets, like Venus (shown above) have a different atmosphere than Earth? Credit: ESA

    Here on Earth, we tend to take our atmosphere for granted, and not without reason. Our atmosphere has a lovely mix of nitrogen and oxygen (78% and 21% respectively) with trace amounts of water vapor, carbon dioxide and other gaseous molecules. What’s more, we enjoy an atmospheric pressure of 101.325 kPa, which extends to an altitude of about 8.5 km.

    In short, our atmosphere is plentiful and life-sustaining. But what about the other planets of the Solar System? How do they stack up in terms of atmospheric composition and pressure? We know for a fact that they are not breathable by humans and cannot support life. But just what is the difference between these balls of rock and gas and our own?

    For starters, it should be noted that every planet in the Solar System has an atmosphere of one kind or another. And these range from incredibly thin and tenuous (such as Mercury’s “exosphere”) to the incredibly dense and powerful – which is the case for all of the gas giants. And depending on the composition of the planet, whether it is a terrestrial or a gas/ice giant, the gases that make up its atmosphere range from either the hydrogen and helium to more complex elements like oxygen, carbon dioxide, ammonia and methane.

    Mercury’s Atmosphere:

    Mercury is too hot and too small to retain an atmosphere. However, it does have a tenuous and variable exosphere that is made up of hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10-14 bar (one-quadrillionth of Earth’s atmospheric pressure). It is believed this exosphere was formed from particles captured from the Sun, volcanic outgassing and debris kicked into orbit by micrometeorite impacts.

    Mercury's Horizon
    A High-resolution Look over Mercury’s Northern Horizon. Credit: NASA/MESSENGER

    Because it lacks a viable atmosphere, Mercury has no way to retain the heat from the Sun. As a result of this and its high eccentricity, the planet experiences considerable variations in temperature. Whereas the side that faces the Sun can reach temperatures of up to 700 K (427° C), while the side in shadow dips down to 100 K (-173° C).

    Venus’ Atmosphere:

    Surface observations of Venus have been difficult in the past, due to its extremely dense atmosphere, which is composed primarily of carbon dioxide with a small amount of nitrogen. At 92 bar (9.2 MPa), the atmospheric mass is 93 times that of Earth’s atmosphere and the pressure at the planet’s surface is about 92 times that at Earth’s surface.

    Venus is also the hottest planet in our Solar System, with a mean surface temperature of 735 K (462 °C/863.6 °F). This is due to the CO²-rich atmosphere which, along with thick clouds of sulfur dioxide, generates the strongest greenhouse effect in the Solar System. Above the dense CO² layer, thick clouds consisting mainly of sulfur dioxide and sulfuric acid droplets scatter about 90% of the sunlight back into space.

    Another common phenomena is Venus’ strong winds, which reach speeds of up to 85 m/s (300 km/h; 186.4 mph) at the cloud tops and circle the planet every four to five Earth days. At this speed, these winds move up to 60 times the speed of the planet’s rotation, whereas Earth’s fastest winds are only 10-20% of the planet’s rotational speed.

    Venus flybys have also indicated that its dense clouds are capable of producing lightning, much like the clouds on Earth. Their intermittent appearance indicates a pattern associated with weather activity, and the lightning rate is at least half of that on Earth.

    Earth’s Atmosphere:

    Earth’s atmosphere, which is composed of nitrogen, oxygen, water vapor, carbon dioxide and other trace gases, also consists of five layers. These consists of the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. As a rule, air pressure and density decrease the higher one goes into the atmosphere and the farther one is from the surface.

    Closest to the Earth is the Troposphere, which extends from the 0 to between 12 km and 17 km (0 to 7 and 10.56 mi) above the surface. This layer contains roughly 80% of the mass of Earth’s atmosphere, and nearly all atmospheric water vapor or moisture is found in here as well. As a result, it is the layer where most of Earth’s weather takes place.

    The Stratosphere extends from the Troposphere to an altitude of 50 km (31 mi). This layer extends from the top of the troposphere to the stratopause, which is at an altitude of about 50 to 55 km (31 to 34 mi). This layer of the atmosphere is home to the ozone layer, which is the part of Earth’s atmosphere that contains relatively high concentrations of ozone gas.

    Space Shuttle Endeavour sillouetted against the atmosphere. The orange layer is the troposphere, the white layer is the stratosphere and the blue layer the mesosphere.[1] (The shuttle is actually orbiting at an altitude of more than 320 km (200 mi), far above all three layers.) Credit: NASA
    Space Shuttle Endeavour sillouetted against the atmosphere. The orange layer is the troposphere, the white layer is the stratosphere and the blue layer the mesosphere. Credit: NASA

    Next is the Mesosphere, which extends from a distance of 50 to 80 km (31 to 50 mi) above sea level. It is the coldest place on Earth and has an average temperature of around -85 °C (-120 °F; 190 K). The Thermosphere, the second highest layer of the atmosphere, extends from an altitude of about 80 km (50 mi) up to the thermopause, which is at an altitude of 500–1000 km (310–620 mi).

    The lower part of the thermosphere, from 80 to 550 kilometers (50 to 342 mi), contains the ionosphere – which is so named because it is here in the atmosphere that particles are ionized by solar radiation.  This layer is completely cloudless and free of water vapor. It is also at this altitude that the phenomena known as Aurora Borealis and Aurara Australis are known to take place.

    The Exosphere, which is outermost layer of the Earth’s atmosphere, extends from the exobase – located at the top of the thermosphere at an altitude of about 700 km above sea level – to about 10,000 km (6,200 mi). The exosphere merges with the emptiness of outer space, and is mainly composed of extremely low densities of hydrogen, helium and several heavier molecules including nitrogen, oxygen and carbon dioxide

    The exosphere is located too far above Earth for any meteorological phenomena to be possible. However, the Aurora Borealis and Aurora Australis sometimes occur in the lower part of the exosphere, where they overlap into the thermosphere.

    This photo of the aurora was taken by astronaut Doug Wheelock from the International Space Station on July 25, 2010. Credit: Image Science & Analysis Laboratory, NASA Johnson Space Center
    Photo of the aurora taken by astronaut Doug Wheelock from the International Space Station on July 25, 2010. Credit: NASA/Johnson Space Center

    The average surface temperature on Earth is approximately 14°C; but as already noted, this varies. For instance, the hottest temperature ever recorded on Earth was 70.7°C (159°F), which was taken in the Lut Desert of Iran. Meanwhile, the coldest temperature ever recorded on Earth was measured at the Soviet Vostok Station on the Antarctic Plateau, reaching an historic low of -89.2°C (-129°F).

    Mars’ Atmosphere:

    Planet Mars has a very thin atmosphere which is composed of 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. The atmosphere is quite dusty, containing particulates that measure 1.5 micrometers in diameter, which is what gives the Martian sky a tawny color when seen from the surface. Mars’ atmospheric pressure ranges from 0.4 – 0.87 kPa, which is equivalent to about 1% of Earth’s at sea level.

    Because of its thin atmosphere, and its greater distance from the Sun, the surface temperature of Mars is much colder than what we experience here on Earth. The planet’s average temperature is -46 °C (51 °F), with a low of -143 °C (-225.4 °F) during the winter at the poles, and a high of 35 °C (95 °F) during summer and midday at the equator.

    The planet also experiences dust storms, which can turn into what resembles small tornadoes. Larger dust storms occur when the dust is blown into the atmosphere and heats up from the Sun. The warmer dust filled air rises and the winds get stronger, creating storms that can measure up to thousands of kilometers in width and last for months at a time. When they get this large, they can actually block most of the surface from view.

    Mars, as it appears today, Credit: NASA
    Mars, as it appears today, with a very thin and tenuous atmosphere. Credit: NASA

    Trace amounts of methane have also been detected in the Martian atmosphere, with an estimated concentration of about 30 parts per billion (ppb). It occurs in extended plumes, and the profiles imply that the methane was released from specific regions – the first of which is located between Isidis and Utopia Planitia (30°N 260°W) and the second in Arabia Terra (0°N 310°W).

    Ammonia was also tentatively detected on Mars by the Mars Express satellite, but with a relatively short lifetime. It is not clear what produced it, but volcanic activity has been suggested as a possible source.

    Jupiter’s Atmosphere:

    Much like Earth, Jupiter experiences auroras near its northern and southern poles. But on Jupiter, the auroral activity is much more intense and rarely ever stops. The intense radiation, Jupiter’s magnetic field, and the abundance of material from Io’s volcanoes that react with Jupiter’s ionosphere create a light show that is truly spectacular.

    Jupiter also experiences violent weather patterns. Wind speeds of 100 m/s (360 km/h) are common in zonal jets, and can reach as high as 620 kph (385 mph). Storms form within hours and can become thousands of km in diameter overnight. One storm, the Great Red Spot, has been raging since at least the late 1600s. The storm has been shrinking and expanding throughout its history; but in 2012, it was suggested that the Giant Red Spot might eventually disappear.

    Jupiter is perpetually covered with clouds composed of ammonia crystals and possibly ammonium hydrosulfide. These clouds are located in the tropopause and are arranged into bands of different latitudes, known as “tropical regions”. The cloud layer is only about 50 km (31 mi) deep, and consists of at least two decks of clouds: a thick lower deck and a thin clearer region.

    There may also be a thin layer of water clouds underlying the ammonia layer, as evidenced by flashes of lightning detected in the atmosphere of Jupiter, which would be caused by the water’s polarity creating the charge separation needed for lightning. Observations of these electrical discharges indicate that they can be up to a thousand times as powerful as those observed here on the Earth.

    Saturn’s Atmosphere:

    The outer atmosphere of Saturn contains 96.3% molecular hydrogen and 3.25% helium by volume. The gas giant is also known to contain heavier elements, though the proportions of these relative to hydrogen and helium is not known. It is assumed that they would match the primordial abundance from the formation of the Solar System.

    Trace amounts of ammonia, acetylene, ethane, propane, phosphine and methane have been also detected in Saturn’s atmosphere. The upper clouds are composed of ammonia crystals, while the lower level clouds appear to consist of either ammonium hydrosulfide (NH4SH) or water. Ultraviolet radiation from the Sun causes methane photolysis in the upper atmosphere, leading to a series of hydrocarbon chemical reactions with the resulting products being carried downward by eddies and diffusion.

    Saturn’s atmosphere exhibits a banded pattern similar to Jupiter’s, but Saturn’s bands are much fainter and wider near the equator. As with Jupiter’s cloud layers, they are divided into the upper and lower layers, which vary in composition based on depth and pressure. In the upper cloud layers, with temperatures in range of 100–160 K and pressures between 0.5–2 bar, the clouds consist of ammonia ice.

    Water ice clouds begin at a level where the pressure is about 2.5 bar and extend down to 9.5 bar, where temperatures range from 185–270 K. Intermixed in this layer is a band of ammonium hydrosulfide ice, lying in the pressure range 3–6 bar with temperatures of 290–235 K. Finally, the lower layers, where pressures are between 10–20 bar and temperatures are 270–330 K, contains a region of water droplets with ammonia in an aqueous solution.

    On occasion, Saturn’s atmosphere exhibits long-lived ovals, similar to what is commonly observed on Jupiter. Whereas Jupiter has the Great Red Spot, Saturn periodically has what’s known as the Great White Spot (aka. Great White Oval). This unique but short-lived phenomenon occurs once every Saturnian year, roughly every 30 Earth years, around the time of the northern hemisphere’s summer solstice.

    These spots can be several thousands of kilometers wide, and have been observed in 1876, 1903, 1933, 1960, and 1990. Since 2010, a large band of white clouds called the Northern Electrostatic Disturbance have been observed enveloping Saturn, which was spotted by the Cassini space probe. If the periodic nature of these storms is maintained, another one will occur in about 2020.

    The winds on Saturn are the second fastest among the Solar System’s planets, after Neptune’s. Voyager data indicate peak easterly winds of 500 m/s (1800 km/h). Saturn’s northern and southern poles have also shown evidence of stormy weather. At the north pole, this takes the form of a hexagonal wave pattern, whereas the south shows evidence of a massive jet stream.

    The persisting hexagonal wave pattern around the north pole was first noted in the Voyager images. The sides of the hexagon are each about 13,800 km (8,600 mi) long (which is longer than the diameter of the Earth) and the structure rotates with a period of 10h 39m 24s, which is assumed to be equal to the period of rotation of Saturn’s interior.

    The south pole vortex, meanwhile, was first observed using the Hubble Space Telescope. These images indicated the presence of a jet stream, but not a hexagonal standing wave. These storms are estimated to be generating winds of 550 km/h, are comparable in size to Earth, and believed to have been going on for billions of years. In 2006, the Cassini space probe observed a hurricane-like storm that had a clearly defined eye. Such storms had not been observed on any planet other than Earth – even on Jupiter.

    Uranus’ Atmosphere:

    As with Earth, the atmosphere of Uranus is broken into layers, depending upon temperature and pressure. Like the other gas giants, the planet doesn’t have a firm surface, and scientists define the surface as the region where the atmospheric pressure exceeds one bar (the pressure found on Earth at sea level). Anything accessible to remote-sensing capability – which extends down to roughly 300 km below the 1 bar level – is also considered to be the atmosphere.

    Diagram of the interior of Uranus. Credit: Public Domain
    Diagram of the interior of Uranus. Credit: Public Domain

    Using these references points, Uranus’  atmosphere can be divided into three layers. The first is the troposphere, between altitudes of -300 km below the surface and 50 km above it, where pressures range from 100 to 0.1 bar (10 MPa to 10 kPa). The second layer is the stratosphere, which reaches between 50 and 4000 km and experiences pressures between 0.1 and 10-10 bar (10 kPa to 10 µPa).

    The troposphere is the densest layer in Uranus’ atmosphere. Here, the temperature ranges from 320 K (46.85 °C/116 °F) at the base (-300 km) to 53 K (-220 °C/-364 °F) at 50 km, with the upper region being the coldest in the solar system. The tropopause region is responsible for the vast majority of Uranus’s thermal infrared emissions, thus determining its effective temperature of 59.1 ± 0.3 K.

    Within the troposphere are layers of clouds – water clouds at the lowest pressures, with ammonium hydrosulfide clouds above them. Ammonia and hydrogen sulfide clouds come next. Finally, thin methane clouds lay on the top.

    In the stratosphere, temperatures range from 53 K (-220 °C/-364 °F) at the upper level to between 800 and 850 K (527 – 577 °C/980 – 1070 °F) at the base of the thermosphere, thanks largely to heating caused by solar radiation. The stratosphere contains ethane smog, which may contribute to the planet’s dull appearance. Acetylene and methane are also present, and these hazes help warm the stratosphere.

    Uranus. Image credit: Hubble
    Uranus, as imaged by the Hubble Space Telescope. Image credit: NASA/Hubble

    The outermost layer, the thermosphere and corona, extend from 4,000 km to as high as 50,000 km from the surface. This region has a uniform temperature of 800-850 (577 °C/1,070 °F), although scientists are unsure as to the reason. Because the distance to Uranus from the Sun is so great, the amount of sunlight absorbed cannot be the primary cause.

    Like Jupiter and Saturn, Uranus’s weather follows a similar pattern where systems are broken up into bands that rotate around the planet, which are driven by internal heat rising to the upper atmosphere. As a result, winds on Uranus can reach up to 900 km/h (560 mph), creating massive storms like the one spotted by the Hubble Space Telescope in 2012. Similar to Jupiter’s Great Red Spot, this “Dark Spot” was a giant cloud vortex that measured 1,700 kilometers by 3,000 kilometers (1,100 miles by 1,900 miles).

    Neptune’s Atmosphere:

    At high altitudes, Neptune’s atmosphere is 80% hydrogen and 19% helium, with a trace amount of methane. As with Uranus, this absorption of red light by the atmospheric methane is part of what gives Neptune its blue hue, although Neptune’s is darker and more vivid. Because Neptune’s atmospheric methane content is similar to that of Uranus, some unknown constituent is thought to contribute to Neptune’s more intense coloring.

    Neptune’s atmosphere is subdivided into two main regions: the lower troposphere (where temperature decreases with altitude), and the stratosphere (where temperature increases with altitude). The boundary between the two, the tropopause, lies at a pressure of 0.1 bars (10 kPa). The stratosphere then gives way to the thermosphere at a pressure lower than 10-5 to 10-4 microbars (1 to 10 Pa), which gradually transitions to the exosphere.

    Neptune’s spectra suggest that its lower stratosphere is hazy due to condensation of products caused by the interaction of ultraviolet radiation and methane (i.e. photolysis), which produces compounds such as ethane and ethyne. The stratosphere is also home to trace amounts of carbon monoxide and hydrogen cyanide, which are responsible for Neptune’s stratosphere being warmer than that of Uranus.

    In this image, the colors and contrasts were modified to emphasize the planet’s atmospheric features. The winds in Neptune’s atmosphere can reach the speed of sound or more. Neptune’s Great Dark Spot stands out as the most prominent feature on the left. Several features, including the fainter Dark Spot 2 and the South Polar Feature, are locked to the planet’s rotation, which allowed Karkoschka to precisely determine how long a day lasts on Neptune. (Image: Erich Karkoschka)
    A modified color/contrast image emphasizing Neptune’s atmospheric features, including wind speed. Credit Erich Karkoschka)

    For reasons that remain obscure, the planet’s thermosphere experiences unusually high temperatures of about 750 K (476.85 °C/890 °F). The planet is too far from the Sun for this heat to be generated by ultraviolet radiation, which means another heating mechanism is involved – which could be the atmosphere’s interaction with ion’s in the planet’s magnetic field, or gravity waves from the planet’s interior that dissipate in the atmosphere.

    Because Neptune is not a solid body, its atmosphere undergoes differential rotation. The wide equatorial zone rotates with a period of about 18 hours, which is slower than the 16.1-hour rotation of the planet’s magnetic field. By contrast, the reverse is true for the polar regions where the rotation period is 12 hours.

    This differential rotation is the most pronounced of any planet in the Solar System, and results in strong latitudinal wind shear and violent storms. The three most impressive were all spotted in 1989 by the Voyager 2 space probe, and then named based on their appearances.

    The first to be spotted was a massive anticyclonic storm measuring 13,000 x 6,600 km and resembling the Great Red Spot of Jupiter. Known as the Great Dark Spot, this storm was not spotted five later (Nov. 2nd, 1994) when the Hubble Space Telescope looked for it. Instead, a new storm that was very similar in appearance was found in the planet’s northern hemisphere, suggesting that these storms have a shorter life span than Jupiter’s.

    Reconstruction of Voyager 2 images showing the Great Black spot (top left), Scooter (middle), and the Small Black Spot (lower right). Credit: NASA/JPL
    Reconstruction of Voyager 2 images showing the Great Black spot (top left), Scooter (middle), and the Small Black Spot (lower right). Credit: NASA/JPL

    The Scooter is another storm, a white cloud group located farther south than the Great Dark Spot – a nickname that first arose during the months leading up to the Voyager 2 encounter in 1989. The Small Dark Spot, a southern cyclonic storm, was the second-most-intense storm observed during the 1989 encounter. It was initially completely dark; but as Voyager 2 approached the planet, a bright core developed and could be seen in most of the highest-resolution images.

    In sum, the planet’s of our Solar System all have atmospheres of sorts. And compared to Earth’s relatively balmy and thick atmosphere, they run the gamut between very very thin to very very dense. They also range in temperatures from the extremely hot (like on Venus) to the extreme freezing cold.

    And when it comes to weather systems, things can equally extreme, with planet’s boasting either weather at all, or intense cyclonic and dust storms that put storms here n Earth to shame. And whereas some are entirely hostile to life as we know it, others we might be able to work with.

    We have many interesting articles about planetary atmosphere’s here at Universe Today. For instance, he’s What is the Atmosphere?, and articles about the atmosphere of MercuryVenusMarsJupiterSaturnUranus and Neptune,

    For more information on atmospheres, check out NASA’s pages on Earth’s Atmospheric LayersThe Carbon Cycle, and how Earth’s atmosphere differs from space.

    Astronomy Cast has an episode on the source of the atmosphere.

    Source: This article was published universetoday.com By Matt Williams

    Categorized in Science & Tech

    Earth is a pretty nifty place. I mean, I’ve spent my entire life here and I’m guessing you have, too, and there’s plenty to see and do, but why is it here at all? For a long time, researchers have tried to answer that question with varying degrees of success, but a new theory of how Earth formed is gaining traction, and it might be the explanation we’ve been looking for.

    The most widely-accepted explanation for how Earth and most terrestrial plants formed hinges on materials orbiting a newborn star — in this case, our sun — which bunched up and formed planets. It’s a fine theory, but some researchers have grown increasingly skeptical that the materials that make up our planet, which is rocky and iron-rich, could have stuck together on their own.

    A new idea, introduced by Alexander Hubbard, a Ph.D. in Astronomy who now works with the American Museum of Natural History, turns to the sun for an explanation. Hubbard has proposed that the sun went through a period of intense volatility in which essentially roasted much of the material in its immediate vicinity, stretching as far as Mars. The softened materials would have been the right consistency to bunch up and form planets, and would explain why the rocky worlds of Mercury, Venus, Earth and Mars sprung up.

    Hubbard’s theory isn’t just a random guess; He’s basing the idea on observed behavior of an infant star which went through a phase just like the one he’s proposing of our own sun. FU Orionis was first observed rapidly brightening in 1936 and at present it shines over 100 times brighter than it did when originally observed. If our own sun pulled the same trick in its early life it could have been exactly what was needed to form our planet.

    Source: This article was published on bgr.com by Mike Wehner


    Categorized in Science & Tech
    The Sunday Times just dropped its highly anticipated Sunday Times Rich List, which ranks the wealthiest people in Britain, as well as the rest of the world.Data from the list shows that it is actually entrepreneurs and self-made business people who dominate the top spots — not just mainly those with inherited wealth.While, of course, there are families that keep passing their companies and wealth down in the family, such as the owners of Koch Industries, Walmart, and even the L'Oreal cosmetics empire, there are an increasing amount of self-made billionaires from across the globe. Most of these self-made people are in the tech industry, such as China's Jack Ma of Alibaba and Mark Zuckerberg from Facebook.Check out who are the wealthiest people on earth:

    33. Alain & Gerard Wertheimer: Net worth — £18.9 billion ($24.5 billion). The brothers (pictured here with the Queen), own and control the House of Chanel perfume company.

    33. Alain & Gerard Wertheimer: Net worth — £18.9 billion ($24.5 billion). The brothers (pictured here with the Queen), own and control the House of Chanel perfume company.
    Getty

    32. Samuel and Donald Newhouse: Net worth — £19.9 billion ($25. 8 billion). The brothers are heirs to Advance Publications, a multimillion-dollar publishing and broadcasting empire which includes The New Yorker and Vogue.

    32. Samuel and Donald Newhouse: Net worth — £19.9 billion ($25. 8 billion). The brothers are heirs to Advance Publications, a multimillion-dollar publishing and broadcasting empire which includes The New Yorker and Vogue.
    President of Advance Publications Donald Newhouse, Newscaster Paula Zahn and Katherine Newhouse Mele.Getty

    31. Ma Huateng (Pony Ma): Net worth — £20.1 billion ($26.09 billion). The Chinese internet entrepreneur is the founder, president, CEO and executive board member of Tencent. Tencent is a holding company for subsidiaries that provide everything from online advertising, media, entertainment, and payment systems.

    31. Ma Huateng (Pony Ma): Net worth — £20.1 billion ($26.09 billion). The Chinese internet entrepreneur is the founder, president, CEO and executive board member of Tencent. Tencent is a holding company for subsidiaries that provide everything from online advertising, media, entertainment, and payment systems.
    Tencent Chairman & Chief Executive Officer Pony Ma attends a news conference announcing the company's results in Hong Kong March 18, 2015REUTERS/Bobby Yip

    T=28. George Soros: Net worth — £20.7 billion ($26.87 billion). Soros is one of the world's most famous and successful investors. However he started from humble beginnings where he worked as a railway porter and waiter to put himself through his university education at the London School of Economics.

    T=28. George Soros: Net worth — £20.7 billion ($26.87 billion). Soros is one of the world's most famous and successful investors. However he started from humble beginnings where he worked as a railway porter and waiter to put himself through his university education at the London School of Economics.
    Georges Soros, Chairman of Soros Fund Management in 2016.Reuters

    T=28. Phil Knight: Net worth — £20.7 billion ($26.87 billion). Knight is the co-founder and chairman emeritus of one of the world's largest and most recognisable sports brands, Nike.

    T=28. Phil Knight: Net worth — £20.7 billion ($26.87 billion). Knight is the co-founder and chairman emeritus of one of the world's largest and most recognisable sports brands, Nike.
    Christian Petersen/Getty Images

    T=28. Maria Franca Fissolo: Net worth — £20.7 billion ($26.87 billion). The Italian billionaire is the owner of Europe's second largest confectionery company Ferrero. She is a widow of Michele Ferrero.

    T=28. Maria Franca Fissolo: Net worth — £20.7 billion ($26.87 billion). The Italian billionaire is the owner of Europe's second largest confectionery company Ferrero. She is a widow of Michele Ferrero.
    Maria Franca Fissolo.YouTube/Gazzetta D'Alba

    27. Mukesh Ambani: Net worth — £21.8 billion ($28.29 billion). Ambani, pictured on the right of former UK chancellor George Osborne, is the chairman, managing director and largest shareholder of a Fortune Global 500 company Reliance Industries Limited (RIL).

    26. Axel Dumas: Net worth — £22.2 billion ($28.8 billion). He is the CEO of major fashion house Hermès. He is the sixth-generation member of the family to lead it after his family founded it in 1837.

    26. Axel Dumas: Net worth — £22.2 billion ($28.8 billion). He is the CEO of major fashion house Hermès. He is the sixth-generation member of the family to lead it after his family founded it in 1837.
    Vittorio Zunino Celotto / Getty

    25. The Henkel family: Net worth — £22.5 billion ($28.88 billion). The German chemical and consumer goods company was founded in 1876 by Fritz Henkel. Christoph Henkel inherited a £1 billion stake in the group in 1999 shortly after his father Konrad's death in 1999.

    25. The Henkel family: Net worth — £22.5 billion ($28.88 billion). The German chemical and consumer goods company was founded in 1876 by Fritz Henkel. Christoph Henkel inherited a £1 billion stake in the group in 1999 shortly after his father Konrad's death in 1999.
    Reuters / Ina Fassbender

    24. Steve Ballmer: Net worth — £23.6 billion ($30.63 billion). He was the former CEO of Microsoft from January 2000 to February 2014 and is the current owner of the basketball team, the Los Angeles Clippers.

    24. Steve Ballmer: Net worth — £23.6 billion ($30.63 billion). He was the former CEO of Microsoft from January 2000 to February 2014 and is the current owner of the basketball team, the Los Angeles Clippers.
    REUTERS/Robert Galbraith

    23. Jorge Paulo Lemann: Net worth — £23.9 billion ($31 billion). Pictured on the left, Lemann is the richest person in Brazil and made his fortune as a corporate takeover legend.

    23. Jorge Paulo Lemann: Net worth — £23.9 billion ($31 billion). Pictured on the left, Lemann is the richest person in Brazil and made his fortune as a corporate takeover legend.
    Scott Olson/Getty Images

    22. Sheldon Adelson: Net worth — £24.6 billion ($31.93 billion). He is the founder and CEO of gambling giant Las Vegas Sands Corp and is a major Republican party donor.

    22. Sheldon Adelson: Net worth — £24.6 billion ($31.93 billion). He is the founder and CEO of gambling giant Las Vegas Sands Corp and is a major Republican party donor.
    Kin Cheung/AP

    21. Li Ka-shing: Net worth — £25.4 billion ($32.97 billion). He is one of Asia's richest men after being one of the first big investors in Facebook while also acquiring British telecom company O2, which he purchased in 2015 for $15 billion.

    21. Li Ka-shing: Net worth — £25.4 billion ($32.97 billion). He is one of Asia's richest men after being one of the first big investors in Facebook while also acquiring  British telecom company O2, which he purchased in 2015 for $15 billion.
    Stanford University, Flickr

    20. Wang Jianlin: Net worth — £25.7 billion ($33.36 billion). He is the founder of China's largest real estate developer Dalian Wanda Group and also owns a 20% stake in Spanish football club Atlético Madrid.

    20. Wang Jianlin: Net worth — £25.7 billion ($33.36 billion). He is the founder of  China's largest real estate developer Dalian Wanda Group and also owns a 20% stake in Spanish football club Atlético Madrid.
    Damir Sogolj / Reuters

    19. Jack Ma: Net worth — £26.7 billion ($26.7 billion). The Chinese tech billionaire is the founder and executive chairman of e-commerce giant Alibaba Group.

    19. Jack Ma: Net worth — £26.7 billion ($26.7 billion). The Chinese tech billionaire is the founder and executive chairman of e-commerce giant Alibaba Group.
    Jack Ma, Executive Chairman of Alibaba REUTERS/Lucy Nicholson

    18. Ingvar Kamprad and family: Net worth — £28 billion ($36.34 billion). The Swedish business magnate has been at the helm of IKEA, one of the world's largest furniture stores and most beloved brands, for more than 70 years.

    17. Karl & Theo Albrecht Jr & Beate Heister and family: Net worth — £30.5 billion ($39.59 billion). Germany's Karl Albrecht founded the discount supermarket chain Aldi with his brother Theo.

    17. Karl & Theo Albrecht Jr & Beate Heister and family: Net worth — £30.5 billion ($39.59 billion). Germany's Karl Albrecht founded the discount supermarket chain Aldi with his brother Theo.
    In this July 30, 2002 file photo a man carries two plastic bags in front of an ALDI market in Gelsenkirchen, Germany. AP Photo /Martin Meissner, file

    16. Stefan Quandt & Susanne Klatten: Net worth — £30.8 billion ($39.98 billion). He is the son of the late Herbert and Johanna Quandt, and owns 25.6% of BMW while his sister claims a 20.8%.

    16. Stefan Quandt & Susanne Klatten: Net worth — £30.8 billion ($39.98 billion). He is the son of the late Herbert and Johanna Quandt, and owns 25.6% of BMW while his sister claims a 20.8%.
    Stefan Quandt in 1999.Reuters

    15. Liliane Bettencourt: Net worth — £31.8 billion ($41.28 billion). She is the heiress to the L'Oreal cosmetics fortune and the company's largest shareholder.

    15. Liliane Bettencourt: Net worth — £31.8 billion ($41.28 billion). She is the heiress to the L'Oreal cosmetics fortune and the company's largest shareholder.
    REUTERS/Benoit Tessier

    14. Sergey Brin: Net worth: £33.4 billion ($43.35 billion). The Russian American computer scientist co-founded tech giant Google with Larry Page.

    13. Larry Page: Net worth — £34.2 billion. Page beats his cofounder of Google counterpart, Sergey Brin, by £1 billion.

    13. Larry Page: Net worth — £34.2 billion. Page beats his cofounder of Google counterpart, Sergey Brin, by £1 billion.
    Chris Hondros/Getty Images

    12. Bernard Arnault: Net worth — £35.2 billion ($45.69 billion). Arnault is the Chairman and CEO of the world's largest luxury goods company, LVMH.

    12. Bernard Arnault: Net worth — £35.2 billion ($45.69 billion). Arnault is the Chairman and CEO of the world's largest luxury goods company, LVMH.
    Reuters/Charles Platiau

    11. Michael Bloomberg: Net worth — £39 billion ($50.62 billion). He is the founder, owners and CEO of the huge global financial services, mass media, and software company Bloomberg. He has also pledged half of his fortune to charity after his death.

    11. Michael Bloomberg: Net worth — £39 billion ($50.62 billion). He is the founder, owners and CEO of the huge global financial services, mass media, and software company Bloomberg. He has also pledged half of his fortune to charity after his death.
    Lori Hoffman/Bloomberg

    10. Larry Ellison: Net worth — £40.6 billion ($52.7 billion). He is the founder and chairman of the international giant Oracle. He is also big into yacht racing and buying whole Hawaiian islands.

    10. Larry Ellison: Net worth — £40.6 billion ($52.7 billion). He is the founder and chairman of the international giant Oracle. He is also big into yacht racing and buying whole Hawaiian islands.
    Oracle executive chairman Larry EllisonOracle

    9. Carlos Slim Helu and family: Net worth — £46 billion ($59.71 billion). He is Mexico's wealthiest man and one of the richest self-made billionaires in the world after taking control of Latin America's biggest mobile telecom firm America Movil.

    9. Carlos Slim Helu and family: Net worth — £46 billion ($59.71 billion). He is Mexico's wealthiest man and one of the richest self-made billionaires in the world after taking control of Latin America's biggest mobile telecom firm America Movil.
    Reuters

    8. Mark Zuckerberg: Net worth — £47.7 billion ($61.92 billion). The 32-year-old is the chairman, CEO, and cofounder of social networking giant Facebook.

    8. Mark Zuckerberg: Net worth — £47.7 billion ($61.92 billion). The 32-year-old is the chairman, CEO, and cofounder of social networking giant Facebook.
    Founder and CEO of Facebook Mark Zuckerber gives his speech during the presentation of the new Samsung Galaxy S7 and Samsung Galaxy S7 edge on February 21, 2016 in Barcelona, Spain. David Ramos/Getty Images

    7. John & Jacqueline Mars: Net worth — £49 billion ($63.6 billion). The brother and sister are heirs to the confectionary empire that makes Mars Bars.

    7. John & Jacqueline Mars: Net worth — £49 billion ($63.6 billion). The brother and sister are heirs to the confectionary empire that makes Mars Bars.
    Reuters

    6. Warren Buffett: Net worth — £61.6 billion ($79.96 billion). The legendary investor is also considered the most successful investor in the world, as chairman and largest shareholder of Berkshire Hathaway. He has also promised to give 99% of his fortune away to philanthropic causes.

    5. Jeff Bezos: Net worth — £61.8 billion ($80.22 billion). He is the founder, chairman, and CEO of the world's largest online shopping retailer Amazon. He is also an investor in Business Insider through his personal investment company Bezos Expeditions.

    4. Amancio Ortega: Net worth — £63.5 billion ($82.42 billion). Ortega founded Inditex in 1985, which owns brands like Zara, Pull & Bear, Bershka, and Massimo Dutti. He also owns around 60% of the company.

    4. Amancio Ortega: Net worth — £63.5 billion ($82.42 billion). Ortega founded Inditex  in 1985, which owns brands like Zara, Pull & Bear, Bershka, and Massimo Dutti. He also owns around 60% of the company.
    Amancio Ortega attends the International Jumping of Monte Carlo in 2012.Piovanotto Marco/ABACA/PA Images

    3. Bill Gates: Net worth — £70.8 billion ($91.9 billion). Gates made his fortune from cofounding the world's largest PC software company Microsoft.

    2. Charles & David Koch: Net worth — £78.9 billion ($102.4 billion). Charles has been the chairman and CEO of the US' second largest private company Koch Industries since 1967. It is a family run business and his brother David is vice president.

    2. Charles & David Koch: Net worth — £78.9 billion ($102.4 billion). Charles has been the chairman and CEO of the US' second largest private company Koch Industries since 1967. It is a family run business and his brother David is vice president.
    Charles (left) and David KochYouTube still, Reuters

    1. The Walton family: Net worth — £100.6 billion ($130.59 billion). The American family are the founders of the world's largest retailer, Walmart. The three most prominent living members are Jim, Rob and Alice.

    1. The Walton family: Net worth — £100.6 billion ($130.59 billion). The American family are the founders of the world's largest retailer, Walmart. The three most prominent living members are Jim, Rob and Alice.
    Walton family members (L to R) Jim, Rob and Alice Walton speak onstage at the Wal-Mart annual meeting in Fayetteville, Arkansas, June 5, 2015.Reuters
    Source : This article was published businessinsider.com By Lianna Brinded
    Categorized in Business Research

    NASA’s Cassini spacecraft is currently conducting a series of elaborate dives in which it repeatedly comes closer to Saturn than ever before. But during its slower periods, NASA is still using the craft’s fantastic photography equipment to grab images of Saturn’s nearby bodies, such as the moon Titan. The latest photo from the agency shows Titan in all its glory, complete with some very volatile cloud cover.

    The new images, which were captured by Cassini on May 7th but not released immediately, show Titan in impressive detail, with long, feathery streaks of clouds obscuring portions of the landscape. But unlike the clouds we’re used to here on Earth — which are made of extremely tiny water droplets or bits of crystalized ice — the clouds you see in the Titan photos are actually made of methane.

    In addition to Titan’s wealth of atmospheric methane, the planet also has vast lakes thought to be primarily made up of liquid ethane and methane, along with nitrogen. That’s an extremely hostile combination, at least in terms of Earth-like life. However, NASA isn’t ruling out the possibility that there may actually be methane-based life on the large moon, and even has some theories as to how it might survive.

    According to NASA, these new photos were snapped at a distance of about 316,000 miles, which means that each pixel of the image equals roughly 2 miles. With that scale in mind, take a look at the dark splotches dotting the top of the image. Those are the huge methane-filled seas, which may or may not be home to huge, methane-filled whales.

    Source : This article was published bgr news By Mike Wehner

    Categorized in Science & Tech

    Here’s an artist’s rendering of a large asteroid breaking up as it begins to plow through Earth’s atmosphere. If it lands it could do a lot of damage, but how much would depend on its size and collision site.ATPACK223/ISTOCKPHOTO

    Every now and then a really big rock from space comes careening through Earth’s atmosphere. Depending on its size, angle of approach and where it lands, few people may notice — or millions could face a risk of imminent death.

    Concern about these occasional, but potentially catastrophic, events keeps some astronomers scanning the skies. Using all types of technologies, they’re scouting for a killer asteroid, one that could snuff out life in a brief but dramatic cataclysm. They’re also looking for ways to potentially deter an incoming biggie from an earthboard path.

    But if a big space rock were to make it to Earth’s surface, what could people expect? That’s a question planetary scientists have been asking themselves — and their computers. And some of their latest answers might surprise you. 

    For instance, it’s not likely a tsunami will take you out. Nor an earthquake. Few would need to even worry about being vaporized by the friction-heated space rock. No, gusting winds and shock waves set off by falling and exploding space rocks would claim the most lives. That’s one of the conclusions of a new computer model.

    Explainer: What are Asteroids? 

    It investigated the likely outcomes of more than a million possible asteroid impacts. In one extreme case, a space rock 200 meters (660 feet) wide whizzes 20 kilometers (12 miles) per second into London, England. This smashup would kill more than 8.7 million people, computers estimate. And nearly three-quarters of those expected to die in that doomsday scenario would lose their lives to winds and shock waves.

    Clemens Rumpf and his colleagues reported this online March 27 in Meteoritics & Planetary Science. Rumpf is a planetary scientist in England at the University of Southampton.

    In a second report, Rumpf’s group looked at 1.2 million potential smashups. Here, the asteroids could be up to 400 meters (1,300 feet) across. Again, winds and shock waves were the big killers. They’d account for about six in every 10 deaths across the spectrum of asteroid sizes, the computer simulations showed.

    Many previous studies had suggested tsunamis would be the top killer. But in these analyses, those killer waves claimed only around one in every five of the lives lost.

    Explainer: What is a tsunami?

    Even asteroids that explode before reaching Earth’s surface can generate high-speed wind gusts, shock waves of pressure in the atmosphere and intense heat. Space rocks big enough to survive the descent pose  far greater risks. They can spawn earthquakes, tsunamis, flying debris — and, of course, gaping craters.

    “These asteroids aren’t an everyday concern,” Rumpf observes. Yet clearly, he notes, the risks they pose “can be severe.” His team describes just how severe they could be in a paper posted online April 19 in Geophysical Research Letters.

    Previous studies typically considered individually each possible effect of an asteroid impact. Rumpf’s group instead looked at them collectively. Quantifying the estimated hazard posed by each effect, says Steve Chesley, might one day help some leaders make one of the hardest calls imaginable — work to deflect an asteroid or just let it hit. Chesley is a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. (NASA stands for National Aeronautics and Space Administration.) Chesley was not involved with either of the new studies.

    Story continues below image.

    asteroid Earth
    Computer simulations reveal that most of the deaths caused by an earthbound asteroid (illustrated) would come from gusting winds and shock waves.
    puchan/iStockphoto
     

    Land hits would pose the biggest risks

    The 1.2 million simulated asteroid impacts each fell into one of 50,000 scenarios. They varied in location, speed and angle of strike. Each scenario was run for 24 different asteroids. Their diameters ranged from 15 to 400 meters (50 to 1,300 feet). About 71 percent of the Earth is covered by water, so the simulations let asteroids descend over water in nearly 36,000 of the scenarios (about 72 percent).

    The researchers began with a map of human populations. Then they added in data on the likely energy that a falling asteroid would unleash at a given site. Existing casualty data from studies of extreme weather and nuclear blasts helped the scientists calculate death rates at different distances from a space rock’s point of impact. All that was then combined into the computer model to gauge how deadly each modeled impact would likely be.

    Explainer: What is a computer model?

    The most deadly one would have killed around 117 million people. Many asteroid hits, however, would pose no threat, the simulations found. More than half of asteroids smaller than 60 meters (200 feet) across caused zero deaths. And no asteroids smaller than 18 meters (60 feet) across led to deaths. Rocks smaller than 56 meters (180 feet) wide didn’t even make it to Earth’s surface before exploding in the atmosphere. Those explosions could still be deadly, though. They would generate intense heat that could burn skin, the team found. They also would set off high-speed winds that would hurl debris and trigger pressure waves that could rupture internal organs.

    Where asteroids fell into the ocean, tsunamis became the dominant killer. The giant waves accounted for between seven and eight of every 10 deaths from these asteroid splashdowns. Still, the casualties from water impacts were only a fraction as high as those due to asteroids that smashed into land. (That’s because asteroid-generated tsunamis are relatively small and quickly lose steam as they plow through the ocean, the computer model showed.)

    Heat, wind and shock waves topped the impacts from land smashups, especially if they hit near large population centers.

    Bottom line: For all asteroids big enough to hit Earth’s surface, heat, wind and shock waves caused the most casualties overall. Other land-based effects, such as earthquakes and blast debris, resulted in fewer than 2 percent of total deaths, the computer projected.

    Story continues below image.

    Chelyabinsk meteor
    Large asteroid impacts are rare. Here, a 20-meter- (66-foot-) wide meteor left behind a smoky trail across the sky above Chelyabinsk, Russia, in 2013. Space rocks that big only strike Earth about once every 100 years.
    Alex Alishevskikh/Wikimedia Commons (CC-BY-SA 2.0)
     

    Protecting Earth

    While asteroids have the potential to kill, deadly impacts are rare, Rumpf says. Most space rocks that bombard Earth are tiny. They burn up in the atmosphere, causing little harm.

    Consider the rock that lit up the sky in 2013 and shattered windows around the Russian city of Chelyabinsk. Such 20-meter- (66-foot-) wide meteors strike Earth only about once a century. Far bigger impacts are capable of wiping out species. An asteroid at least 10 kilometers (6 miles) wide that smashed into Earth 66 million years ago has been blamed for wiping out the dinosaurs. Such mega-events are especially rare, however. They may occur only once every 100 million years or so.

    Today, astronomers scan the skies with automated telescopes scouting for those potential killer space rocks. So far, they’ve cataloged 27 percent of those 140 meters (450 feet) or larger whizzing through our solar system.

    asteroid deflector
    If a killer asteroid were detected, heading for Earth, NASA has plans for developing a spacecraft to slam into the space rock, deflecting it to a path that would miss us. Such a system is, however, at least some 20 years away. Once it is available, it might require a warning time of a year or two to target and redirect small asteroids.
    NASA

    Other scientists are analyzing how they might divert or catch an earthbound asteroid. Proposals include whacking the asteroid like a billiard ball with a high-speed spacecraft. Or perhaps part of the asteroid’s surface might be fried with a nearby nuclear blast. The vaporized material should propel the asteroid away like a jet engine.

    Understanding the potential threats — and options available to deal with them — could offer guidance on how people should react to a warning that an asteroid was heading Earth’s way. It might help people decide whether it’s better to evacuate or shelter in place — or even mobilize space troops to try and divert the asteroid.

    “If the asteroid’s in a size range where the damage will be from shock waves or wind, you can easily shelter in place,” Chesley says. He says this should work for even a large population. But if the heat generated as it falls, impacts or explodes “becomes a bigger threat,” he says “and you run the risk of fires — then that changes the response of emergency planners.”

    Making such tough calls will require more information about what the asteroids are made of, says Lindley Johnson. He serves as the “planetary defense” officer for NASA in Washington, D.C. Those properties in part determine an asteroid’s potential for bringing devastation. Rumpf’s team couldn’t consider how those characteristics might vary, Johnson says. But several asteroid-bound missions are planned to provide some answers to such questions.

    For now, making decisions based on the average deaths presented in the new study could be misleading, warns Gareth Collins. He’s a planetary scientist at Imperial College London. A 60-meter- (200-foot-) wide incoming space rock, for instance, would cause an average of 6,300 deaths in the simulations. But just a handful of high-fatality events inflated that average. These included one scenario that resulted in more than 12 million casualties. In fact, most space rocks of that size struck away from population centers in the simulations. And they killed no one. “You have to put it in perspective,” he advises. 


    Death from the skies 

    A new project simulated 1.2 million asteroid strikes on Earth. That let scientists estimate how many deaths could result from each effect of a falling space rock. (Averages for three of the classes of asteroids that were evaluated are shown in the interactive below. People who could have died from two or more effects are included in multiple columns.) 

    Click the graphic to explore the asteroid simulation data. 
    Screenshot 2
    H. THOMPSON AND T. TIBBITTS

    Power Words

    (for more about Power Words, click here)

    angle     The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.

    asteroid     A rocky object in orbit around the sun. Most asteroids orbit in a region that falls between the orbits of Mars and Jupiter. Astronomers refer to this region as the asteroid belt.

    atmosphere     The envelope of gases surrounding Earth or another planet.

    cataclysm     An enormous, violent, natural event. A meteor hitting Earth and wiping out most living species would qualify as a cataclysmic event.

    climate     The weather conditions prevailing in one area, in general, or over a long period.

    climate change     Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and the clearing of forests.

    colleague     Someone who works with another; a co-worker or team member.

    computer model     A program that runs on a computer that creates a model, or simulation, of a real-world feature, phenomenon or event.

    crater     A large, bowl-shaped cavity in the ground or on the surface of a planet or the moon. They are typically caused by an explosion or the impact of a meteorite or other celestial body. Such an impact is sometimes referred to as a cratering event.

    data     Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. 

    death rates     The share of people in a particular, defined group that die per year. Those rates can change if the group is affected by disease or other deadly conditions (such as accidents, natural disasters, extreme heat or war and other sources of violence).

    debris     Scattered fragments, typically of trash or of something that has been destroyed. Space debris, for instance, includes the wreckage of defunct satellites and spacecraft.

    deter     An event, action or material that keeps something from happening. For instance, a visible pothole in the road will deter a driver from steering his car over it.

    diameter     The length of a straight line that runs through the center of a circle or spherical object, starting at the edge on one side and ending at the edge on the far side.

    dinosaur     A term that means terrible lizard. These ancient reptiles lived from about 250 million years ago to roughly 65 million years ago. 

    extinction     The permanent loss of a species, family or larger group of organisms.

    friction     The resistance that one surface or object encounters when moving over or through another material (such as a fluid or a gas). Friction generally causes a heating, which can damage a surface of some material as it rubs against another.

    mechanism     The steps or process by which something happens or “works.” 

    meteor     A lump of rock or metal from space that hits the atmosphere of Earth. In space it is known as a meteoroid. When you see it in the sky it is a meteor. And when it hits the ground it is called a meteorite.

    National Aeronautics and Space Administration     (or NASA) Created in 1958, this U.S. agency has become a leader in space research and in stimulating public interest in space exploration. It was through NASA that the United States sent people into orbit and ultimately to the moon. It has also sent research craft to study planets and other celestial objects in our solar system.

    numerical     Having to do with numbers.

    online     (n.) On the internet. (adj.) A term for what can be found or accessed on the internet.

    organ     (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.

    planetary science     The science of planets other than Earth.

    population     (in biology) A group of individuals from the same species that lives in the same area.

    pressure     Force applied uniformly over a surface, measured as force per unit of area.

    propulsion     The act or process of driving something forward, using a force. For instance, jet engines are one source of propulsion used for keeping airplanes aloft.

    range     The full extent or distribution of something. 

    risk     The chance or mathematical likelihood that some bad thing might happen.

    scenario     An imagined situation of how events or conditions might play out.

    shock waves     Tiny regions in a gas or fluid where properties of the host material change dramatically owing to the passage of some object (which could be a plane in air or merely bubbles in water). Across a shock wave, a region’s pressure, temperature and density spike briefly, and almost instantaneously.

    simulation     (v. simulate) An analysis, often made using a computer, of some conditions, functions or appearance of a physical system. A computer program would do this by using mathematical operations that can describe the system and how it might vary over time or in response to different anticipated situations.

    solar system     The eight major planets and their moons in orbit around our sun, together with smaller bodies in the form of dwarf planets, asteroids, meteoroids and comets.

    telescope     Usually a light-collecting instrument that makes distant objects appear nearer through the use of lenses or a combination of curved mirrors and lenses. Some, however, collect radio emissions (energy from a different portion of the electromagnetic spectrum) through a network of antennas.

    tsunami     One or many long, high sea waves caused by an earthquake, submarine landslide or other disturbance.

    wave     A disturbance or variation that travels through space and matter in a regular, oscillating fashion.

    weather     Conditions in the atmosphere at a localized place and a particular time. It is usually described in terms of particular features, such as air pressure, humidity, moisture, any precipitation (rain, snow or ice), temperature and wind speed. Weather constitutes the actual conditions that occur at any time and place. It’s different from climate, which is a description of the conditions that tend to occur in some general region during a particular month or season.

    Source : This article was published sciencenewsforstudents.org By THOMAS SUMNER

    Categorized in Science & Tech

    This is a view of Enceladus, Saturn's sixth-largest moon, taken by the Cassini spacecraft.

    New research from NASA’s Cassini mission has all eyes on Enceladus, Saturn’s sixth-largest moon. The research, recently published in Science magazine, indicates that plumes of vapor escaping from cracks in the moon’s icy shell are full of molecular hydrogen, the fuel for microbial life.

    As Scott Bolton, a co-author and mission co-investigator from the Southwest Research Institute, explains: “Hydrogen’s the most common element in the whole universe, but we don’t expect a lot of it sitting on Enceladus.” That’s because Enceladus is too small to trap large reserves of hydrogen in its gravity field, he says.

    The inference, of course, is that hydrogen is being produced somewhere on the Saturnian moon. But how? Bolton and his colleagues have an idea — one that could link the global ocean beneath Enceladus’ ice shell with the life-sustaining deep oceans of Earth.

    “The idea that we’ve proposed — and we’ve researched a lot of different ideas trying to come up with an alternative theory — is that actually there’s hydrothermal activity going on deep in the ocean on Enceladus, and it may be producing white and black smokers, kind of like what we see on Earth,” Bolton says.

    He explains that on Earth, smokers are deep hydrothermal vents that put out white or black “smoke” underwater, depending on their sulfur content: “Basically, what you have is you have minerals that are very rich in iron interacting with water.” That chemical process forms new minerals, he says — and releases hydrogen.

    “In other words, under the deep sea, the water meets the rock, and some chemistry occurs, and hydrogen is released,” he explains. At least, that’s how it happens on Earth — and Cassini data has already shown that the ocean on Enceladus lies above a rocky core.

    On Earth, scientists believe that hydrothermal vents were an early source of life. Today, the areas around deep sea vents teem with species that we’re still discovering.

    “You don’t need any sunlight at all,” Bolton says. “You just have the microbes basically feeding off of this hydrogen, and that’s its energy source. And around that region on the Earth in these hydrothermal vents, you find little spider crabs, little shrimp, all kinds of different kinds of mussels.”

    To find a shrimp in Enceladus’ ocean would take a submarine, but Bolton says there’s another place we can look for life: in the water vapor spewing through cracks in the moon’s ice hull.

    “If you can fly a spacecraft through that water mist, you can go in and measure whether there’s microbes, and amino acids, and other kinds of things that might be present in that water,” he says.

    Bolton says that a follow-up probe to Enceladus hasn’t yet been approved, but a mission to one of Jupiter’s moons, Europa, is currently in the works. “It would, hopefully, fly through these plumes,” Bolton says.

    “We’ve seen some plumes coming out of the ice of Europa through Hubble telescope images. And so we would look for something similar as to what we just saw on Enceladus, and even more.”

    UPDATE: A previous version of this story incorrectly stated Europa was a moon of Saturn, it is a moon of Jupiter.

    This article is based on an interview that aired on PRI's Science Friday. Watch a video about the discovery here.

    Source : This article was published in ijpr.org By  JULIA FRANZ, CHRISTIE TAYLOR

    Categorized in Science & Tech

    Scientists have discovered what they believe is one of the biggest impact craters in the world near the Falklands Islands. They say the crater appears to date to between 270 and 250 million years ago, which, if confirmed, would link it to the world’s biggest mass extinction event, where 96 percent of life on Earth was wiped out.

    The presence of a massive crater in the Falklands was first proposed by Michael Rampino, a professor in New York University, in 1992 after he noticed similarities with the Chicxulub crater in Mexico—the asteroid that created this crater is thought to have played a major role in the extinction of the dinosaurs 66 million years ago.

    But after a brief report at the Falklands site, very little research was carried out. Now, a team of scientists—including Rampino—have returned to the area to perform an “exhaustive search for additional new geophysical information” that would indicate the presence of an impact crater.

    Their findings, published in the journal Terra Nova, suggest the huge circular depression just northwest of the islands is indeed the result of the massive impact of an asteroid or meteorite. The basin, which is now buried under sediments, measures over 150 miles in diameter.

    To analyze the site, the team, from the U.S., Argentina and Paraguay, looked at various aspects of the crater, including gravity anomalies and seismic reflection, which allows them to estimate sub-surface properties, along with differences in the chemistry of the rocks.

    Their findings were consistent with other impact craters, with certain features being “very similar to that of the Chicxulub multi-ring impact structure.” They found there was a large magnetic anomaly, suggesting significant variation in rocks at the site, as well as gravitational variations “typical of very large impact structures.”

    asteroid impactArtist impression of an asteroid impacting Earth.

    NASA/DON DAVISFalklands impact craterThe proposed impact crater in the Falkland Islands. The islands are shown in yellow, while the regions of red show a notable increase in Earth's magnetism, characteristic of an impact.

    NATIONAL CENTERS FOR ENVIRONMENTAL INFORMATION.

    Researchers say the crater appears to date to the Late Paleozoic Era—around the same time as the Permian mass extinction event also known as the Great Dying. They believe the crater dates to between 270 and 250 million years ago, but say further investigations are needed to confirm this.

      “Future drilling in this basin is a must” they wrote. “If confirmed as a site of impact, then this structure would be one of the largest known impact structures on Earth.” In a statement, Rampino added: "If the proposed crater turns out to be 250 million years old, it could correlate with the largest mass extinction ever _ the Permian extinctions, which wiped out more than 90 percent of all species.”

      But not everyone is convinced of the link. Michael Benton, a paleontologist from the University of Bristol, told Newsweek in an email interview that while the discovery of an impact basin is interesting, it is not necessarily related to the Great Dying.

      ‘There have been several suggestions that the end-Permian mass extinction was linked to impact, including possible craters off Australia, and this one in the South Atlantic,” he says. “The link of the current crater to the extinction is hugely tenuous—it could be the cause, but evidence is not presented for that idea.

      “It is only tentatively identified as a crater, and its age is estimated as Late Paleozoic—so it could be millions of years older than the critical boundary. Further, there is no evidence elsewhere in the world of the fallout for impact—as we know from the later impact at the end of the Cretaceous [period], you expect to find a shopping list of ten or more indicators of impact scattered worldwide, such as shocked quartz and iridium enrichment, but these have not been found. The study of a new crater is massively important, but it’s unlikely it had anything to do with the end-Permian mass extinction.”

      Source : This article was published in newsweek.com By HANNAH OSBORNE

      Categorized in Science & Tech

      While much of humanity concerns itself with saving the planet from the ravages mankind has inflicted upon it, one of the world’s brightest minds is already warning that we should actually be spending our time planning our ultimate escape. Stephen Hawking — the cosmologist, author, and physicist who holds more awards and honorary titles than should even be allowed — says that we have about 100 years until Earth is a big old pile of gross, and that if we don’t focus our efforts on colonizing other planets, namely Mars, humanity faces complete and total extinction.

      Hawking’s warning that humans should start packing their bags comes as a result of the scientist’s belief that endless peril lies ahead thanks to overpopulation, climate change as a result of pollution, and even the threat of mankind building an AI or even a manmade virus capable of destroying us outright. Hawking has taken the stance that mankind is basically boned before, but his latest prediction is his most dire prediction yet.

      In a new BBC documentary entitled Stephen Hawking: Expedition New Earth, the 75-year-old Hawking will attempt to prove that his theory isn’t as crazy as it seems. “Professor Stephen Hawking thinks the human species will have to populate a new planet within 100 years if it is to survive,” the BBC says. “With climate change, overdue asteroid strikes, epidemics and population growth, our own planet is increasingly precarious.” The documentary will be split into two 60-minute programs and will air on BBC Two before presumably finding its way to western television.

      This article was published on bgr.com by Mike Wehner

      Categorized in Science & Tech
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