Researchers discovered that Proxima b has the right climate for oceans. And extraterrestrials.

Last year, scientists from the U.S., Israel, the U.K, Chile, Poland, Germany, Spain and France discovered an "Earth-like" planet. This planet is juuuust outside our own solar system, only four light years away – that's nothing if you're a flashlight beam! It orbits a red dwarf star called Proxima Centauri, so the scientists creatively dubbed it "Proxima b."

So here's the big deal about Proxima b: It's in a spot that's not too hot or too cold for life. In fact, researchers at France's National Center for Scientific Research think it could be an ocean planet, just like our own.

The scientists proceeded to argue (as scientists are wont to do) over whether the planet could actually sustain life. But thanks to a new series of experiments, the researchers think it could be home to an alien society.

Okay, so that's a little bit of an exaggeration. No little green men or interstellar burger joints spotted thus far. But the experiments do suggest that Proxima b likely has a climate that could support life. The scientists modeled the planet using different atmospheres, amounts of radiation and orbits. Findings from the setups looked promising.

“Overall, our results are in agreement with previous studies in suggesting Proxima Centauri b may well have surface temperatures conducive to the presence of liquid water,” the scientists wrote.

Meanwhile, on Proxima b, a team of alien journalists flying star-powered spaceships are writing about their own discovery: a Proxima b-like planet orbiting a yellow dwarf star known to its inhabitants as "the sun." They're thinking of calling the planet "sun b" (not to be confused with "Sunny D," an alien beverage made of chemicals probably not native to our galaxy).

Source: This article was fromthegrapevine.com By Ilana Strauss

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

A newly discovered planet around a distant star may jump to the top of the list of places where scientists should go looking for alien life. 

Categorized in Science & Tech

A new technique for studying exoplanet atmospheres could make it possible for scientists to get a close look at the atmosphers of planets like Proxima b in the 2020s.

A newly proposed technique could make it possible to search for life on alien planets much sooner than scientists had expected.  

Earlier this year, scientists discovered a planet orbiting the nearest star to Earth's own sun. Although relatively little is known about this newly discovered planet, which was dubbed Proxima b, evidence suggests it's possible that it has the right conditions to support life.

Of course, scientists are eager to look for signs of life on Proxima b (and members of the general public are eager to hear the results). But a deep look at the planet's atmosphere, where signs of life might hide, might require massive, next-generation, space-based telescopes that aren't expected to get off the ground until at least the 2030s. [Giant Space Telescopes of the Future (Infographic)]

But now, at least two different groups of astronomers are investigating a method for doing atmospheric studies of Proxima b — and other, possibly habitable planets like it — using ground-based telescopes that are scheduled to come online in the 2020s, significantly cutting down on the wait time.

Vermin of the sky

Thousands of planets have been identified around stars other than our own, a majority of them in the past six years, thanks to the dedicated Kepler space telescope (although many other observatories have contributed to this exoplanet treasure trove).

But finding planets is much different from characterizing their properties — things such as a planet's mass and diameter; whether it is made of rock or primarily of gas; its surface temperature; whether it has an atmosphere; and what that atmosphere is composed of.  

Earlier this month, at a workshop hosted by the National Academy of Sciences that explored the search for life beyond Earth, Matteo Brogi, a Hubble fellow at the University of Colorado, described a method for studying the atmosphere of Proxima b using next-generation ground-based telescopes.

The approach could be applied to other planets that, like Proxima b, are rocky, and orbit in the habitable zone of relatively cool stars, known as red dwarfs. The astronomical community is already emphasizing the search for "Earth-like" planets around these small stars because the latter are incredibly common in the galaxy; astronomers have even jokingly referred to red dwarfs as the "vermin of the sky."

"The frequency of small planets around small stars is extremely high; on average, there are about 2.5 planets per star," Brogi said. "Regarding habitable planets around small stars, there should be more or less a frequency of close to 30 percent. So every three stars should have a habitable planet."

An accordion of light

The approach Brogi and his colleagues are investigating would combine two different techniques for studying stars and exoplanets. The first is an extremely common technique in astronomy called high-resolution spectroscopy, which essentially looks at light from an object in extremely fine detail.

To understand high-resolution spectroscopy, consider the way sunlight passes through a prism and produces a rainbow; the glass takes the light and fans it out like an accordion, revealing that the whitish colored light is actually composed of various colors.

Spectroscopy spreads the light out even more — stretching that accordion out to unrealistic lengths for a musical instrument — revealing finer and finer detail about the colors (wavelengths) that are contained in the light from stars, planets and other cosmic objects. The resulting band of colors is called an object's spectrum.

The first scientists to use spectroscopy discovered something so amazing that, without it, the field of modern astronomy might be entirely unrecognizable: Chemical elements leave a unique fingerprint in the light spectrum. In other words, if a star is made of hydrogen and helium, those elements will leave a distinct signature on the light the star emits — when astronomers fan out the light from the star, they can see that signature in the wavelengths that are present or not present. This tool has allowed astronomers to learn about the composition of objects billions of light-years away, and helped to uncover the incredible fact that we are all made of stardust.

So if spectroscopy can be applied to the light coming from exoplanets, scientists might get a look at the composition of the planetary atmospheres. It's still unclear to scientists which atmospheric chemical mixtures would strongly indicate the presence of life — most plants on Earth consume carbon dioxide and produce oxygen, and other forms of life produce methane, so a combination with high levels of oxygen and methane might indicate the presence of biology. However, there are potential false positives and false negatives, not to mention potential life-forms that consume and produce different chemicals than living organisms on Earth.

But there are a couple of hurdles standing in the way of performing spectroscopy on a planet, and one of the biggest is that trying to see the light from a planet (which is fairly dim) when it is orbiting right next to a star (which is incredibly bright) is like trying to see the glow of a firefly against a backdrop of 1,000 stage spotlights (which would be difficult).

So Brogi and his colleagues have proposed a way to help separate those two sources of light. Because the planet is moving around the star, it is also moving toward, and then away from, the Earth throughout its orbit. When a source of light moves toward an observer, the light waves become compressed; when the source moves away from the observer, the light waves become stretched out. This is called the Doppler effect, or redshift. It also happens with sound waves, which is why when a police siren is moving toward you, it sounds like it is increasing in pitch; the waves get pushed together so that they literally have a higher frequency. When the car passes you and starts moving away, it sounds like the siren is getting lower in pitch, because the waves get stretched out and the frequency goes down.

The idea is that, out of the sea of light coming from a distant star, scientists could pick out the island of light coming from the planet by looking for the redshifted/Doppler shifted light. (This also could be used to separate any interference from Earth's own atmosphere.) Looking for those shifts in the light also falls under the header of spectroscopy.

Nonetheless, the Doppler shift approach wouldn't be powerful enough to work on its own, and this is where the second technique comes in: Astronomers would need to directly image the star or planet system first.

The planet-finding technique known as "direct imaging" is pretty much what it sounds like: an attempt to get a direct snapshot of both a planet and the star it orbits. To do this, scientists try to reduce the star's blinding glare enough so that they can see the light from the planet. It's a challenging method and one that can't be done for just any system — the planet has to be sufficiently bright compared to its parent star, which means most of the planets seen with direct imaging thus far are gas giants like Jupiter, and oriented in such a way that it can be viewed clearly from Earth. 

So Brogi and his colleagues proposed the method of first directly imaging the planetary system, using that image to locate the planet, and then further separating the planet's light from the star's light using the Doppler method. From there, they can use high-resolution spectroscopy to learn about the planet's atmosphere.

Telescopes currently in operation don't have the sensitivity to make this plan a reality, but some very large telescopes currently under development could. These scopes should be able to directly image smaller planets, as long as those planets are orbiting dimmer stars. Those include the Giant Magellan Telescope, scheduled to turn on around 2021, and the European Extremely Large Telescope, set to begin taking data as early as 2024. Direct imaging capabilities are likely to improve by leaps and bounds with these telescopes, but with direct imaging alone, it will likely not be possible to characterize many Earth-size, potentially habitable worlds.

During his talk, Brogi said there should be "on the order of 10" potentially habitable planets that this method could identify and study.

Challenges and progress

Brogi noted that there are caveats to the plan. For example, many of the predictions that he and his team made about how sensitive the method would be were "based on best-case scenarios," so dealing with real data will undoubtedly pose challenges. Moreover, the method compares the observed planetary spectra with laboratory experiments that recreate the expected spectra for various chemical elements, which means any errors in that laboratory work will carry over into the planet studies. But overall, Brogi said he and his colleagues think the approach could provide a better glimpse of the atmospheres of small, rocky, potentially habitable planets than scientists are likely to see for a few decades.

They aren't the only group that thinks so. Researchers based at the California Institute of Technology (Caltech) are investigating this approach as well, according to Dimitri Mawet, an associate professor of astronomy at Caltech. Mawet and his colleagues call the approach high dispersion coronagraphy (HDC) — a combination of high-resolution spectroscopy and high-contrast imaging techniques (direct imaging). (Similar lines of thought have been proposed by other groups.)

Mawet told Space.com in an email that he and his colleagues recently submitted two research papers that explore the "practical limits of HDC" and demonstrate "a promising instrument concept in the lab at Caltech." He said he and his colleagues plan to test the technique using the Keck telescope, located in Hawaii, "about two years from now," to study young, giant planets (so not very Earth-like). He confirmed that to use the technique to study small, rocky planets like Proxima b, scientists will have to wait for those next-generation, ground-based telescopes, like the Giant Magellan Telescope and the European Extremely Large Telescope. He also confirmed Brogi's estimation of "on the order of 10" rocky exoplanets in the habitable zone of their stars that could be studied using this technique.

"As [Brogi] mentioned, there are several caveats associated with the HDC technique," Mawet told Space.com. "However, we are working on addressing them and, in the process, studying the fundamental limits of the technique. Our initial results are very promising, and exciting."

Follow Calla Cofield@callacofield.Follow us@Spacedotcom,Facebook andGoogle+. Original article onSpace.com.

Categorized in Science & Tech

The exoplanet OGLE-2016-BLG-1195Lb, as illustrated by NASA. Image: NASA

The National Aeronautics Space Administration (NASA) continues its venture to the unknown and have discovered yet another planet similar to ours.

Categorized in Science & Tech

A newfound alien world is quite Earth-like in some ways, but you wouldn't want to live there.

The exoplanet, known as OGLE-2016-BLG-1195Lb, is about as massive as Earth and orbits its star at about the same distance Earth circles the sun. But OGLE-2016-BLG-1195Lb's parent star is tiny and dim, meaning the alien planet is likely far too cold to host life, its discoverers said.

OGLE-2016-BLG-1195Lb is not in Earth's neck of the cosmic woods; the alien world lies nearly 13,000 light-years away. The astronomers spotted it using a technique called gravitational microlensing, which involves watching what happens when a massive body passes in front of a star. The closer object's gravity bends and magnifies the background star's light, acting like a lens. [7 Ways to Discover Alien Planets]

In many cases, the foreground object is a star as well. If this star has orbiting planets, their existence can be inferred based on their influence on the background star's light curve. And that's indeed what happened with OGLE-2016-BLG-1195Lb.

The planet's microlensing signal was first spotted by the Optical Gravitational Lensing Experiment (OGLE), a ground-based survey managed by the University of Warsaw in Poland (hence the newfound world's name).

The discovery team then used NASA's Spitzer Space Telescope and the Korea Microlensing Telescope Network — a system of three telescopes, one each in Chile, Australia and South Africa — to track and study the microlensing event.

These combined observations revealed the existence of OGLE-2016-BLG-1195Lb, and allowed researchers to calculate its mass and orbital distance. That mass is remarkable, it turns out.

"This 'iceball' planet is the lowest-mass planet ever found through microlensing," Yossi Shvartzvald, a NASA postdoctoral fellow based at the agency's Jet Propulsion Laboratory (JPL) in Pasadena, California, said in a statement. Shvartzvald is lead author of the study announcing the new planet's existence, which was published online Wednesday (April 26) in the Astrophysical Journal Letters. (You can read the paper for free at the journal's website.)

The team was also able to determine that OGLE-2016-BLG-1195Lb's host star is tiny, containing just 7.8 percent the mass of Earth's sun.

That's so small that the parent may not be a proper star at all, researchers said: Its mass is right on the boundary between the "failed stars" known as brown dwarfs and ultracool dwarf stars such as TRAPPIST-1, which hosts seven recently discovered Earth-size planets.

Screenshot 5

Three or four of the TRAPPIST-1 planets may be capable of supporting life, but they orbit much closer to their star than OGLE-2016-BLG-1195Lb does. Indeed, all seven of the known TRAPPIST-1 worlds would fit inside the orbit of Mercury, if they were transported to our own solar system.

Like two other planets detected by Spitzer via microlensing, OGLE-2016-BLG-1195Lb lies in the Milky Way galaxy's flat disk, not its central bulge.

"Although we only have a handful of planetary systems with well-determined distances that are this far outside our solar system, the lack of Spitzer detections in the bulge suggests that planets may be less common toward the center of our galaxy than in the disk," study co-author Geoff Bryden, an astronomer at JPL, said in the same statement.

Originally published on Space.com. By Mike Wall

Categorized in Science & Tech

In this artist tendering provided by M. Weiss Harvard-Smithsonian Center for Astrophysics, a newly-discovered rocky exoplanet, LHS 1140b. This planet is located in the liquid water habitable zone surrounding its host star, a small, faint red star named LHS 1140. The planet weighs about 6.6 times the mass of Earth and is shown passing in front of LHS 1140. Depicted in blue is the atmosphere the planet may have retained. (M. Weiss Harvard-Smithsonian Center for Astrophysics via AP)

WASHINGTON (AP) — Astronomers have found yet another planet that seems to have just the right Goldilocks combination for life: Not so hot and not so cold. It's not so far away, either.

This new, big, dense planet is rocky, like Earth, and has the right temperatures for water, putting it in the habitable zone for life, according to a study published Wednesday in the journal Nature .

It's the fifth such life-possible planet outside our solar system revealed in less than a year, but still relatively nearby Earth. Rocky planets within that habitable zone of a star are considered the best place to find evidence of some form of life.

"It is astonishing to live in a time when discovery of potentially habitable worlds is not only commonplace but proliferating," said MIT astronomer Sara Seager, who wasn't part of the study.

The first planet outside our solar system was discovered in 1995, but thanks to new techniques and especially NASA's planet-hunting Kepler telescope, the number of them has exploded in recent years. Astronomers have now identified 52 potentially habitable planets and more than 3,600 planets outside our solar system.

The latest discovery, called LHS 1140b, regularly passes in front of its star, allowing astronomers to measure its size and mass. That makes astronomers more confident that this one is rocky, compared to other recent discoveries.

In the next several years, new telescopes should be able to use the planet's path to spy its atmosphere in what could be the best-aimed search for signs of life, said Harvard astronomer David Charbonneau, a co-author of the study. If scientists see both oxygen and some carbon in an atmosphere, that's a promising sign that something could be living.

Outside astronomers have already put this new planet near the top of their must-see lists for new ground and space-based telescopes.

"This is the first one where we actually know it's rocky," Charbonneau said. "We found a planet that we can actually study that might be actually Earth-like."

Make that super-sized, because it belongs to a class of planets called super-Earths that are more massive than Earth but not quite the size of giants Neptune or Jupiter.

Compared to Earth, the new planet is big, pushing near the size limit for rocky planets. It's 40 percent wider than Earth but it has 6.6 times Earth's mass, giving it a gravitational pull three times stronger, Charbonneau said. A person weighing 167 pounds would feel like 500 pounds on this planet.

While many super-Earths are too big to have the right environment for life, 1140b is just small enough to make it a good candidate. Thirty-two of the potentially habitable planets found so far are considered super-Earth sized.

The new planet was found using eight small telescopes in Chile and help from an amateur planet-hunter, Charbonneau said.

In the constellation Cetus, it is 39 light years or 230 trillion miles away. So are a group of seven mostly Earth-sized planets in or near the habitable zone found circling a star called Trappist-1 earlier this year, but it in a different direction. And in August, astronomers found that the nearest planet to Earth outside our solar system, only 25 trillion miles away, also could have the right temperature for life, but astronomers can't get a peek at its atmosphere.

"If you picture the Milky Way as the size of the United States, then these systems are all within the size of Central Park," Charbonneau said. "These are your neighbors."

The latest discoveries have their founders at odds over which of the planets are the most promising. Charbonneau said recent studies show that the Trappist planets may not be rocky like Earth, while Trappist discoverer Michael Gillon said the newest planet has such intense gravity that its atmosphere may be smooshed down so telescopes can't get a good look at it.

Seven outside astronomers said the Milky Way is big enough for all the discoveries to be exciting, requiring more exploring.

Yale astronomer Greg Laughlin, who wasn't part of any of the teams, praised all the new findings but said the Trappist planets seem too light and the new one too dense for his taste: "I wouldn't book a trip to any of these planets."

Source : yahoo.com

Categorized in Science & Tech

In this artist tendering provided by M. Weiss Harvard-Smithsonian Center for Astrophysics, a newly-discovered rocky exoplanet, LHS 1140b. This planet is located in the liquid water habitable zone surrounding its host star, a small, faint red star named LHS 1140. The planet weighs about 6.6 times the mass of Earth and is shown passing in front of LHS 1140. Depicted in blue is the atmosphere the planet may have retained. (M. Weiss Harvard-Smithsonian Center for Astrophysics via AP)

WASHINGTON (AP) — Astronomers have found yet another planet that seems to have just the right Goldilocks combination for life: Not so hot and not so cold. It's not so far away, either.

This new, big, dense planet is rocky, like Earth, and has the right temperatures for water, putting it in the habitable zone for life, according to a study published Wednesday in the journal Nature .

It's the fifth such life-possible planet outside our solar system revealed in less than a year, but still relatively nearby Earth. Rocky planets within that habitable zone of a star are considered the best place to find evidence of some form of life.

"It is astonishing to live in a time when discovery of potentially habitable worlds is not only commonplace but proliferating," said MIT astronomer Sara Seager, who wasn't part of the study.

The first planet outside our solar system was discovered in 1995, but thanks to new techniques and especially NASA's planet-hunting Kepler telescope, the number of them has exploded in recent years. Astronomers have now identified 52 potentially habitable planets and more than 3,600 planets outside our solar system.

The latest discovery, called LHS 1140b, regularly passes in front of its star, allowing astronomers to measure its size and mass. That makes astronomers more confident that this one is rocky, compared to other recent discoveries.

In the next several years, new telescopes should be able to use the planet's path to spy its atmosphere in what could be the best-aimed search for signs of life, said Harvard astronomer David Charbonneau, a co-author of the study. If scientists see both oxygen and some carbon in an atmosphere, that's a promising sign that something could be living.

Outside astronomers have already put this new planet near the top of their must-see lists for new ground and space-based telescopes.

"This is the first one where we actually know it's rocky," Charbonneau said. "We found a planet that we can actually study that might be actually Earth-like."

Make that super-sized, because it belongs to a class of planets called super-Earths that are more massive than Earth but not quite the size of giants Neptune or Jupiter.

Compared to Earth, the new planet is big, pushing near the size limit for rocky planets. It's 40 percent wider than Earth but it has 6.6 times Earth's mass, giving it a gravitational pull three times stronger, Charbonneau said. A person weighing 167 pounds would feel like 500 pounds on this planet.

While many super-Earths are too big to have the right environment for life, 1140b is just small enough to make it a good candidate. Thirty-two of the potentially habitable planets found so far are considered super-Earth sized.

The new planet was found using eight small telescopes in Chile and help from an amateur planet-hunter, Charbonneau said.

In the constellation Cetus, it is 39 light years or 230 trillion miles away. So are a group of seven mostly Earth-sized planets in or near the habitable zone found circling a star called Trappist-1 earlier this year, but it in a different direction. And in August, astronomers found that the nearest planet to Earth outside our solar system, only 25 trillion miles away, also could have the right temperature for life, but astronomers can't get a peek at its atmosphere.

"If you picture the Milky Way as the size of the United States, then these systems are all within the size of Central Park," Charbonneau said. "These are your neighbors."

The latest discoveries have their founders at odds over which of the planets are the most promising. Charbonneau said recent studies show that the Trappist planets may not be rocky like Earth, while Trappist discoverer Michael Gillon said the newest planet has such intense gravity that its atmosphere may be smooshed down so telescopes can't get a good look at it.

Seven outside astronomers said the Milky Way is big enough for all the discoveries to be exciting, requiring more exploring.

Yale astronomer Greg Laughlin, who wasn't part of any of the teams, praised all the new findings but said the Trappist planets seem too light and the new one too dense for his taste: "I wouldn't book a trip to any of these planets."

Source : yahoo.com

Categorized in Science & Tech

It seemed as though there was a piece missing from the solar system when Pluto got declassified as a planet and reclassified as a dwarf planet instead. Since then, several other Pluto-like bodies have been discovered beyond the orbit of Neptune, but none that qualify as being a planet, unfortunately. However, all is not lost as more recently indirect evidence points to a Uranus-sized planet lurking near the outer edge of the solar system.

Categorized in Science & Tech

Researchers announced Wednesday the stunning discovery of seven Earth-like planets orbiting a small star in our galaxy, opening up the most promising hunting ground so far for life beyond the Solar System.

SCROLL DOWN FOR MORE VIDEOS

All seven roughly match the size and mass of our own planet and are almost certainly rocky, and three are perfectly perched to harbour life-nurturing oceans of water, they reported in the journal Nature.

WATCH THE PRESS CONFERENCE ANNOUNCING THE DISCOVERY

Most critically, their proximity to Earth and the dimness of their red dwarf star, called Trappist-1, will allow astronomers to parse each one’s atmosphere in search of chemical signatures of biological activity.

“We have made a crucial step towards finding life out there,” said co-author Amaury Triaud, a scientist at the University of Cambridge.

“Up to now, I don’t think we have had the right planets to find out,” he said in a press briefing.

Earth-like

“Now we have the right target.”

The Trappist-1 system, a mere 39 light years distant, has the largest number of Earth-sized planets known to orbit a single star.

It also has the most within the so-called “temperate zone” — not so hot that water evaporates, nor so cold that it freezes rock-solid.

The discovery adds to growing evidence that our home galaxy, the Milky Way, may be populated with tens of billions of worlds not unlike our own — far more than previously suspected.

Remarkably, professional stargazers may simply have been looking in the wrong place.

“The great idea of this approach was to study planets around the smallest stars of the galaxy, and close to us,” said lead author Michael Gillon, a professor at the University of Liege in Belgium.

 ‘ULTRACOOL’ DWARF STAR 

“That is something nobody did before us — most astronomers were focused on stars like our Sun,” he told journalists ahead of publication.

Gillon and his team began to track Trappist-1 — a so-called “ultracool” dwarf star with less than 10 percent the mass of the Sun — with a dedicated telescope in 2010, and reported last year on three planets in its orbit.

They detected the invisible exoplanets using the so-called “transit” method: when an orbiting world passes between a star and an astronomer peering through a telescope, it dims the starlight by a tiny but measurable amount.

But when subsequent calculations didn’t quite tally, Gillon realised that there might be other stars that had escaped Earth-bound observation.

“So we requested time with NASA’s Spitzer Space Telescope,” said co-author Emmanuel Jehin, also at the University of Liege.

“This allowed us to get 20 consecutive 24-hour periods of observation, which was crucial to discovering that we had seven transiting planets.”

360 VIDEO

Looking from Earth, the astronomers could only track activity around the star at night.

“From space, we observed continually and matched all the transits,” 34 in all.

Compared to the distance between our Sun and its planets, the Trappist-1 family is very tightly bunched.

Indeed, the dwarf star and its seven satellites — with orbits ranging from 1.5 to 12 days — would all fit comfortably in the distance between the Sun and its closest planet, Mercury.

Trappist

 LIKE A SUNSET

If Earth were that close to the Sun, it would be a hellish ball of fire.

But because Trappist-1 emits far less radiation, temperatures on its planets — depending on the atmosphere — could be between zero and 100 degrees Celsius (32 and 212 degrees Fahrenheit), the scientists said.

Gillon and his team have started to analyse the chemical make-up of the atmospheres.

“There is at least one combination of molecules, if present with relative abundance, that would tell us there is life, with 99 percent confidence,” said Gillon.

A certain mix of methane, oxygen or ozone, and carbon dioxide, for example, could almost certainly come only from biological sources.

“But except for detecting a message from beyond our solar system from intelligence out there, we will never be 100 percent sure,” he added.

Someone standing on, say, Trappist-1 D, E or F — the three middle planets — would have a breathtaking panorama of the star and its system, Triaud said.

The red dwarf — which would loom 10 times larger than the Sun in our sky — would be a “deep crimson” shading into a salmon-like colour, he said.

“The view would be beautiful — you would have about 200 times less light that from the Sun on Earth at midday,” he added.

“It would be like the end of a sunset.”

Author : AFP

Source : https://arynews.tv/en/watch-live-nasa-news-conference-to-present-new-findings-on-planets-that-orbit-stars-other-than-earth/

Categorized in Science & Tech
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