Saturn’s bizarre polar hexagon is really hazy

A view of Saturn, its rings and its north polar hexagon, as captured by Cassini on November 27, 2013. Image via NASA/ JPL/ SSI/ Lights in the Dark.

Did you know that Saturn has a huge, persistent, hexagonal (six-sided) cloud formation at its north pole? Saturn’s hexagon is one of the most unusual and easily recognized features in the solar system. Now, a new study from researchers at the University of the Basque Country in Spain has revealed details about a multi-layered, sandwich-like haze that hangs above the hexagon itself. The findings come from an examination of images taken by the Hubble Space Telescope as well as those sent back by the Cassini spacecraft, which orbited Saturn from 2004 to 2017.

The results were published in a new peer-reviewed paper in Nature Communications on May 8, 2020.

The hazes above Saturn’s hexagon were first seen by Cassini in June 2015 in high-resolution images of the planet’s limb taken by the spacecraft’s main camera. Those images captured details as small as 0.6 to 1.2 miles (1-2 km) in size. Cassini was able to see the hazes as well as analyze their composition, using color filters from ultraviolet to near-infrared.

The hazes are above the clouds that form the hexagon. The scientists identified at least seven distinct haze layers.

A closer look at Saturn’s north polar hexagon, captured by Cassini; the inset shows a closeup of the haze layers above the hexagon. Image via UPV/ EHU/ EurekAlert!.

Agustín Sánchez-Lavega, who led the study, stated:

The Cassini images have enabled us to discover that, just as if a sandwich had been formed, the hexagon has a multi-layered system of at least seven mists that extend from the summit of its clouds to an altitude of more than 300 km (186 miles) above them. Other cold worlds, such as Saturn’s satellite Titan or the dwarf planet Pluto, also have layers of hazes, but not in such numbers nor as regularly spaced out.

From the paper:

In June 2015, Cassini high-resolution images of Saturn’s limb southwards of the planet’s hexagonal wave revealed a system of at least six stacked haze layers above the upper cloud deck. Here, we characterize those haze layers and discuss their nature. Vertical thickness of layers ranged from 7 to 18 km [4-11 mi], and they extended in altitude about 130 km [80 mi], from pressure level 0.5 bar to 0.01 bar. Above them, a thin but extended aerosol layer reached altitude about 340 km [211 mi] (0.4 mbar). Radiative transfer modeling of spectral reflectivity shows that haze properties are consistent with particles of diameter 0.07–1.4 um and number density 100–500 cm-3. The nature of the hazes is compatible with their formation by condensation of hydrocarbon ices, including acetylene and benzene at higher altitudes. Their vertical distribution could be due to upward propagating gravity waves generated by dynamical forcing by the hexagon and its associated eastward jet.

Illustration of the layers in Saturn’s atmosphere, including haze on top. Image via KHadley.com.

Hubble was also able to see the hexagon from above, not just on the limb of Saturn, as with Cassini.

The new study of the hexagon and its hazes shows just how complex this weather system and other meteorological phenomena are in Saturn’s deep and turbulent hydrogen atmosphere.

Each haze layer is between 4.3 to 11 miles (seven to 18 kilometers) thick and composed of very tiny particles about one micrometer (one-millionth of a meter) in size. Based on the Cassini data, the particles are composed of hydrocarbon ice crystallites, such as acetylene, propyne, propane, diacetylene and perhaps butane. This is like nothing found on Earth, but that isn’t too surprising, since Saturn’s atmosphere is mostly hydrogen and is much colder than Earth’s, between minus 184 and minus 292 Fahrenheit (minus 120 and minus 180 degrees Celsius).

The researchers also found that the hazes have a regular vertical distribution, thought to be caused by the vertical propagation of gravity waves that produce oscillations in the density and temperature of the atmosphere. This is common, and has been observed on other planets as well, including Earth. According to the researchers, the gravity waves may be caused by the hexagon itself and the powerful jet stream that races around it. Even on Earth, such gravity waves have been seen, produced by jet streams that travel at 62 miles per hour (100 kilometers per hour), from west to east in the mid-latitudes. On giant Saturn, though, the gravity waves and jet streams are much faster and more powerful.

High-resolution overhead view from Cassini of Saturn’s hexagon in motion. A massive hurricane is in the center of the hexagon and many other smaller storms can also be seen. The colors are from different wavelengths, from ultraviolet to visible light, combined to make the movie. Image via NASA Science.

The hexagon was a surprising and fascinating discovery by Cassini. When viewed directly from above, it looks almost perfect, like a giant piece of artwork floating over Saturn’s north pole. At the center of the hexagon is a massive churning hurricane, with an eye 50 times larger than the average hurricane’s eye on Earth. Many other smaller vortices are also seen within the hexagon, some of which are swept along with the jet stream.

You can see the movement of the features within the hexagon in this high-resolution movie. While hurricanes on Earth generally last about a week or so, this hexagon and central hurricane are thought to have been there for at least decades, if not centuries. As Andrew Ingersoll from the former Cassini imaging team said:

The hexagon is just a current of air, and weather features out there that share similarities to this are notoriously turbulent and unstable. A hurricane on Earth typically lasts a week, but this has been here for decades – and who knows – maybe centuries.

Santiago Pérez-Hoyos, Agustín Sánchez-Lavega, Teresa del Río-Gaztelurrutia and Ricardo Hueso, who were involved in the new study. Image via UPV/ EHU/ Campusa.

The stunning beauty of the hexagon, and the intricacy of the layers above it, show how complex Saturn’s atmosphere and weather systems are. In some ways they are reminiscent of storms and weather on Earth, but on a much larger scale, and manifesting in ways unlike anything seen on our own planet.

Bottom line: A new study reveals details of a multi-layered, sandwich-like haze that hangs above the huge hexagon cloud pattern at Saturn’s north pole.

Source: Multilayer hazes over Saturn’s hexagon from Cassini ISS limb images

Via Campusa

from EarthSky https://ift.tt/2yXsIgo

A view of Saturn, its rings and its north polar hexagon, as captured by Cassini on November 27, 2013. Image via NASA/ JPL/ SSI/ Lights in the Dark.

Did you know that Saturn has a huge, persistent, hexagonal (six-sided) cloud formation at its north pole? Saturn’s hexagon is one of the most unusual and easily recognized features in the solar system. Now, a new study from researchers at the University of the Basque Country in Spain has revealed details about a multi-layered, sandwich-like haze that hangs above the hexagon itself. The findings come from an examination of images taken by the Hubble Space Telescope as well as those sent back by the Cassini spacecraft, which orbited Saturn from 2004 to 2017.

The results were published in a new peer-reviewed paper in Nature Communications on May 8, 2020.

The hazes above Saturn’s hexagon were first seen by Cassini in June 2015 in high-resolution images of the planet’s limb taken by the spacecraft’s main camera. Those images captured details as small as 0.6 to 1.2 miles (1-2 km) in size. Cassini was able to see the hazes as well as analyze their composition, using color filters from ultraviolet to near-infrared.

The hazes are above the clouds that form the hexagon. The scientists identified at least seven distinct haze layers.

A closer look at Saturn’s north polar hexagon, captured by Cassini; the inset shows a closeup of the haze layers above the hexagon. Image via UPV/ EHU/ EurekAlert!.

Agustín Sánchez-Lavega, who led the study, stated:

The Cassini images have enabled us to discover that, just as if a sandwich had been formed, the hexagon has a multi-layered system of at least seven mists that extend from the summit of its clouds to an altitude of more than 300 km (186 miles) above them. Other cold worlds, such as Saturn’s satellite Titan or the dwarf planet Pluto, also have layers of hazes, but not in such numbers nor as regularly spaced out.

From the paper:

In June 2015, Cassini high-resolution images of Saturn’s limb southwards of the planet’s hexagonal wave revealed a system of at least six stacked haze layers above the upper cloud deck. Here, we characterize those haze layers and discuss their nature. Vertical thickness of layers ranged from 7 to 18 km [4-11 mi], and they extended in altitude about 130 km [80 mi], from pressure level 0.5 bar to 0.01 bar. Above them, a thin but extended aerosol layer reached altitude about 340 km [211 mi] (0.4 mbar). Radiative transfer modeling of spectral reflectivity shows that haze properties are consistent with particles of diameter 0.07–1.4 um and number density 100–500 cm-3. The nature of the hazes is compatible with their formation by condensation of hydrocarbon ices, including acetylene and benzene at higher altitudes. Their vertical distribution could be due to upward propagating gravity waves generated by dynamical forcing by the hexagon and its associated eastward jet.

Illustration of the layers in Saturn’s atmosphere, including haze on top. Image via KHadley.com.

Hubble was also able to see the hexagon from above, not just on the limb of Saturn, as with Cassini.

The new study of the hexagon and its hazes shows just how complex this weather system and other meteorological phenomena are in Saturn’s deep and turbulent hydrogen atmosphere.

Each haze layer is between 4.3 to 11 miles (seven to 18 kilometers) thick and composed of very tiny particles about one micrometer (one-millionth of a meter) in size. Based on the Cassini data, the particles are composed of hydrocarbon ice crystallites, such as acetylene, propyne, propane, diacetylene and perhaps butane. This is like nothing found on Earth, but that isn’t too surprising, since Saturn’s atmosphere is mostly hydrogen and is much colder than Earth’s, between minus 184 and minus 292 Fahrenheit (minus 120 and minus 180 degrees Celsius).

The researchers also found that the hazes have a regular vertical distribution, thought to be caused by the vertical propagation of gravity waves that produce oscillations in the density and temperature of the atmosphere. This is common, and has been observed on other planets as well, including Earth. According to the researchers, the gravity waves may be caused by the hexagon itself and the powerful jet stream that races around it. Even on Earth, such gravity waves have been seen, produced by jet streams that travel at 62 miles per hour (100 kilometers per hour), from west to east in the mid-latitudes. On giant Saturn, though, the gravity waves and jet streams are much faster and more powerful.

High-resolution overhead view from Cassini of Saturn’s hexagon in motion. A massive hurricane is in the center of the hexagon and many other smaller storms can also be seen. The colors are from different wavelengths, from ultraviolet to visible light, combined to make the movie. Image via NASA Science.

The hexagon was a surprising and fascinating discovery by Cassini. When viewed directly from above, it looks almost perfect, like a giant piece of artwork floating over Saturn’s north pole. At the center of the hexagon is a massive churning hurricane, with an eye 50 times larger than the average hurricane’s eye on Earth. Many other smaller vortices are also seen within the hexagon, some of which are swept along with the jet stream.

You can see the movement of the features within the hexagon in this high-resolution movie. While hurricanes on Earth generally last about a week or so, this hexagon and central hurricane are thought to have been there for at least decades, if not centuries. As Andrew Ingersoll from the former Cassini imaging team said:

The hexagon is just a current of air, and weather features out there that share similarities to this are notoriously turbulent and unstable. A hurricane on Earth typically lasts a week, but this has been here for decades – and who knows – maybe centuries.

Santiago Pérez-Hoyos, Agustín Sánchez-Lavega, Teresa del Río-Gaztelurrutia and Ricardo Hueso, who were involved in the new study. Image via UPV/ EHU/ Campusa.

The stunning beauty of the hexagon, and the intricacy of the layers above it, show how complex Saturn’s atmosphere and weather systems are. In some ways they are reminiscent of storms and weather on Earth, but on a much larger scale, and manifesting in ways unlike anything seen on our own planet.

Bottom line: A new study reveals details of a multi-layered, sandwich-like haze that hangs above the huge hexagon cloud pattern at Saturn’s north pole.

Source: Multilayer hazes over Saturn’s hexagon from Cassini ISS limb images

Via Campusa

from EarthSky https://ift.tt/2yXsIgo

A famous Mars meteorite, now with nitrogen

Martian meteorite ALH 84001 at Johnson Space Center, shortly after being returned from Antarctica. For scale, the black cube is 1 cm (about .4 inch) on a side. The outside of ALH 84001 is partly coated with black fusion crust, typical of freshly fallen meteorites. The interior is a uniform greenish gray. Image via NASA Johnson Space Center/ LPI.

For decades, scientists have been searching for evidence of organic compounds – the building blocks of life – on Mars. The Mars rover Curiosity first confirmed organics in Martian rocks a few years ago. Then, in late April 2020, more exciting news … researchers at the Earth-Life Science Institute in Japan said they have detected 4-billion-year-old nitrogen-containing organic molecules in a famous Martian meteorite, a rock ejected from Mars, likely via an impact event, which traversed interplanetary space and ultimately landed on Earth. The meteorite is none other than Allan Hills 84001 (ALH 84001), a famous Mars meteorite picked up in the snow fields of Antarctica in 1984. This new work – and the discovery of nitrogen in this meteorite – may be a key to understanding how organics originated on Mars and whether any of them might be life-related.

The new peer-reviewed findings were published in Nature Communications on April 24, 2020.

The research team, including scientist Atsuko Kobayashi from the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology and research scientist Mizuho Koike from the Institute of Space and Astronautical Science at Japan Aerospace Exploration Agency (JAXA), found nitrogen-bearing organic material within carbonate minerals inside the meteorite. The organics are estimated to be 4 billion years old. From the paper:

Understanding the origin of organic material on Mars is a major issue in modern planetary science. Recent robotic exploration of Martian sedimentary rocks and laboratory analyses of Martian meteorites have both reported plausible indigenous organic components. However, little is known about their origin, evolution, and preservation. Here we report that 4-billion-year-old (Ga) carbonates in Martian meteorite, Allan Hills 84001, preserve indigenous nitrogen(N)-bearing organics by developing a new technique for high-spatial resolution in situ N-chemical speciation. The organic materials were synthesized locally and/ or delivered meteoritically on Mars during the Noachian age. The carbonates, alteration minerals from the Martian near-surface aqueous fluid, trapped and kept the organic materials intact over long geological times. This presence of N-bearing compounds requires abiotic or possibly biotic N-fixation and ammonia storage, suggesting that early Mars had a less oxidizing environment than today.

A fragment of the Martian meteorite ALH 84001 (left). Enlarged area showing the orange-colored carbonate grains (right). Image via Koike et al. (2020)/ Nature Communications/ ELSI.

Analysis of carbonates in Martian meteorite ALH 84001, which contain the nitrogen-bearing organics (blue bars). Image via Koike et al. (2020)/ Nature Communications/ ELSI.

Possible abiotic ways that nitrogen-containing organics could be created on ancient Mars. Image via Koike et al. (2020)/ Nature Communications/ ELSI.

The carbonate minerals themselves are significant, since they typically precipitate from groundwater on Earth. This adds even more evidence, along with all of the data from various Mars rovers and orbiters, that Mars was once much wetter than it is now, with plentiful organics. Such an environment could have been ideal for life to get a start on the planet.

The researchers used state-of-the-art analytical techniques to determine the nitrogen content inside the carbonates.

So why is the nitrogen important?

First, the team found that the amount of nitrogen in the form of nitrate was insignificant, meaning that early Mars had a much less oxidizing environment than it does today. (Oxidizing is when a substance combines chemically with oxygen or another oxidizing agent. A good example is iron or steel metal rusting in the presence of oxygen and water.) That’s good news for the possible emergence of life, since nitrate is a very strong oxidant. Also, as noted in the paper, these nitrogen-bearing compounds require either abiotic (non-biological) or biotic (biological) fixation. The paper discusses various possible abiotic sources, but unfortunately not the biotic ones.

The Curiosity rover has also found organics in Martian rocks. Image via NASA/ Mars Exploration Program.

While the findings show even more evidence for organics on early Mars, scientists still don’t known exactly how those organics were created. They could be either abiotic, biotic, or both. Meteorites and comets are thought to have delivered at least some of them to the surface of ancient Mars, but other organics are thought to have formed directly on the planet itself.

The researchers also had to make sure that the organics were truly Martian and not terrestrial contamination. To do this, they used silver tape in an ELSI clean lab to pluck off the tiny carbonate grains, which are about the width of a human hair, from the host meteorite. The grains were then prepared to further remove any possible surface contaminants with a scanning electron microscope-focused ion beam instrument at JAXA. In addition, they used a technique called Nitrogen K-edge micro X-ray Absorption Near Edge Structure (µ-XANES) spectroscopy, which allowed them to detect nitrogen present in very small amounts and to determine what chemical form that nitrogen was in. As a comparison, control samples from nearby igneous minerals in the meteorites showed no detectable nitrogen, indicating that the organic molecules were only in the carbonate.

Surface conditions on current Mars are extremely hostile to the preservation of organics, but as this study, and ones based on findings from Curiosity, have shown, organics can still be preserved quite well inside rocks. There also might be plenty of organic compounds in the near-surface of Mars, still waiting to be found. The organics found by Curiosity are in mudstones – composed of clay and silt-sized particles of ancient mud – that used to be at the bottom of lakes in Gale Crater. Future missions, such as the upcoming Perseverance rover, will be able to further determine the abundance of organics still on Mars now.

Atsuko Kobayashi at ELSI, one of the researchers involved in the new study. Image via ELSI.

From the paper:

Whatever the origin, the presence of the organic and reduced nitrogen on early/ middle Noachian Mars indicates the importance of Martian nitrogen cycle. If considerable amounts and variations of organic matter were produced and/or delivered and preserved at the Martian near-surface system over geological time scales, these compounds have a chance to evolve into more complicated forms. It is expected that additional hidden records of the Martian nitrogen cycle will be acquired by future investigations, including a sample return mission from the Martian Moons eXploration (MMX), Mars Sample Return missions, and exploration of the Martian subsurface, as well as further advanced studies of Martian meteorites.

The discovery of nitrogen in some Martian organics is another significant step toward understanding how organic compounds formed on ancient Mars, how abundant they might be and whether any of them could be evidence of life itself.

Bottom line: Researchers have discovered 4-billion-year-old nitrogen-containing organic molecules in Martian meteorites.

Source: In-situ preservation of nitrogen-bearing organics in Noachian Martian carbonates

Via ELSI

from EarthSky https://ift.tt/2WwLTXA

Martian meteorite ALH 84001 at Johnson Space Center, shortly after being returned from Antarctica. For scale, the black cube is 1 cm (about .4 inch) on a side. The outside of ALH 84001 is partly coated with black fusion crust, typical of freshly fallen meteorites. The interior is a uniform greenish gray. Image via NASA Johnson Space Center/ LPI.

For decades, scientists have been searching for evidence of organic compounds – the building blocks of life – on Mars. The Mars rover Curiosity first confirmed organics in Martian rocks a few years ago. Then, in late April 2020, more exciting news … researchers at the Earth-Life Science Institute in Japan said they have detected 4-billion-year-old nitrogen-containing organic molecules in a famous Martian meteorite, a rock ejected from Mars, likely via an impact event, which traversed interplanetary space and ultimately landed on Earth. The meteorite is none other than Allan Hills 84001 (ALH 84001), a famous Mars meteorite picked up in the snow fields of Antarctica in 1984. This new work – and the discovery of nitrogen in this meteorite – may be a key to understanding how organics originated on Mars and whether any of them might be life-related.

The new peer-reviewed findings were published in Nature Communications on April 24, 2020.

The research team, including scientist Atsuko Kobayashi from the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology and research scientist Mizuho Koike from the Institute of Space and Astronautical Science at Japan Aerospace Exploration Agency (JAXA), found nitrogen-bearing organic material within carbonate minerals inside the meteorite. The organics are estimated to be 4 billion years old. From the paper:

Understanding the origin of organic material on Mars is a major issue in modern planetary science. Recent robotic exploration of Martian sedimentary rocks and laboratory analyses of Martian meteorites have both reported plausible indigenous organic components. However, little is known about their origin, evolution, and preservation. Here we report that 4-billion-year-old (Ga) carbonates in Martian meteorite, Allan Hills 84001, preserve indigenous nitrogen(N)-bearing organics by developing a new technique for high-spatial resolution in situ N-chemical speciation. The organic materials were synthesized locally and/ or delivered meteoritically on Mars during the Noachian age. The carbonates, alteration minerals from the Martian near-surface aqueous fluid, trapped and kept the organic materials intact over long geological times. This presence of N-bearing compounds requires abiotic or possibly biotic N-fixation and ammonia storage, suggesting that early Mars had a less oxidizing environment than today.

A fragment of the Martian meteorite ALH 84001 (left). Enlarged area showing the orange-colored carbonate grains (right). Image via Koike et al. (2020)/ Nature Communications/ ELSI.

Analysis of carbonates in Martian meteorite ALH 84001, which contain the nitrogen-bearing organics (blue bars). Image via Koike et al. (2020)/ Nature Communications/ ELSI.

Possible abiotic ways that nitrogen-containing organics could be created on ancient Mars. Image via Koike et al. (2020)/ Nature Communications/ ELSI.

The carbonate minerals themselves are significant, since they typically precipitate from groundwater on Earth. This adds even more evidence, along with all of the data from various Mars rovers and orbiters, that Mars was once much wetter than it is now, with plentiful organics. Such an environment could have been ideal for life to get a start on the planet.

The researchers used state-of-the-art analytical techniques to determine the nitrogen content inside the carbonates.

So why is the nitrogen important?

First, the team found that the amount of nitrogen in the form of nitrate was insignificant, meaning that early Mars had a much less oxidizing environment than it does today. (Oxidizing is when a substance combines chemically with oxygen or another oxidizing agent. A good example is iron or steel metal rusting in the presence of oxygen and water.) That’s good news for the possible emergence of life, since nitrate is a very strong oxidant. Also, as noted in the paper, these nitrogen-bearing compounds require either abiotic (non-biological) or biotic (biological) fixation. The paper discusses various possible abiotic sources, but unfortunately not the biotic ones.

The Curiosity rover has also found organics in Martian rocks. Image via NASA/ Mars Exploration Program.

While the findings show even more evidence for organics on early Mars, scientists still don’t known exactly how those organics were created. They could be either abiotic, biotic, or both. Meteorites and comets are thought to have delivered at least some of them to the surface of ancient Mars, but other organics are thought to have formed directly on the planet itself.

The researchers also had to make sure that the organics were truly Martian and not terrestrial contamination. To do this, they used silver tape in an ELSI clean lab to pluck off the tiny carbonate grains, which are about the width of a human hair, from the host meteorite. The grains were then prepared to further remove any possible surface contaminants with a scanning electron microscope-focused ion beam instrument at JAXA. In addition, they used a technique called Nitrogen K-edge micro X-ray Absorption Near Edge Structure (µ-XANES) spectroscopy, which allowed them to detect nitrogen present in very small amounts and to determine what chemical form that nitrogen was in. As a comparison, control samples from nearby igneous minerals in the meteorites showed no detectable nitrogen, indicating that the organic molecules were only in the carbonate.

Surface conditions on current Mars are extremely hostile to the preservation of organics, but as this study, and ones based on findings from Curiosity, have shown, organics can still be preserved quite well inside rocks. There also might be plenty of organic compounds in the near-surface of Mars, still waiting to be found. The organics found by Curiosity are in mudstones – composed of clay and silt-sized particles of ancient mud – that used to be at the bottom of lakes in Gale Crater. Future missions, such as the upcoming Perseverance rover, will be able to further determine the abundance of organics still on Mars now.

Atsuko Kobayashi at ELSI, one of the researchers involved in the new study. Image via ELSI.

From the paper:

Whatever the origin, the presence of the organic and reduced nitrogen on early/ middle Noachian Mars indicates the importance of Martian nitrogen cycle. If considerable amounts and variations of organic matter were produced and/or delivered and preserved at the Martian near-surface system over geological time scales, these compounds have a chance to evolve into more complicated forms. It is expected that additional hidden records of the Martian nitrogen cycle will be acquired by future investigations, including a sample return mission from the Martian Moons eXploration (MMX), Mars Sample Return missions, and exploration of the Martian subsurface, as well as further advanced studies of Martian meteorites.

The discovery of nitrogen in some Martian organics is another significant step toward understanding how organic compounds formed on ancient Mars, how abundant they might be and whether any of them could be evidence of life itself.

Bottom line: Researchers have discovered 4-billion-year-old nitrogen-containing organic molecules in Martian meteorites.

Source: In-situ preservation of nitrogen-bearing organics in Noachian Martian carbonates

Via ELSI

from EarthSky https://ift.tt/2WwLTXA

After sunset, use Venus to find Mercury

Given clear skies and an unobstructed western horizon, the dazzling planet Venus – and the planet Mercury, our sun’s innermost planet – will be yours to behold after sunset from about mid-May 2020 until nearly the end of this month. It’ll be the Northern Hemisphere’s best evening apparition of Mercury; the Southern Hemisphere has a crack at Mercury, too. To find Mercury in mid-May, first look west after sunset for Venus. You can’t miss it. It’s very, very bright in the west after sunset. Next, draw a line with your mind’s eye between Venus and the sunset point. Mercury will be along that line, below Venus, near the sunset point.

Then watch in the coming evenings, as Mercury ascends in the evening sky, while Venus descends toward its June 3 passage between the Earth and sun. The conjunction of Venus and Mercury will come around May 20 and 21.

View at EarthSky Community Photos. | Radu Anghel caught Mercury just after sunset on May 13, 2020, against a bright twilight sky. He wrote: “Mercury is back on the evening sky. On May 22, it will be right next to Venus! :)” Nice catch, Radu! Thanks for posting.

Venus ranks as the third-brightest celestial object to light up the heavens, after the sun and moon. You might see this brilliant beauty of a planet as little as 15 minutes (or less) after sunset. In mid-May – as Mercury is just beginning its ascent into our evening sky – bring binoculars, if you have them, to locate Mercury sooner after sunset in the bright twilight. With binoculars, you might spot Mercury near the sunset point on the horizon some 30 to 45 minutes after sunset.

Although Mercury is nowhere as bright as Venus, Mercury shines more brilliantly than a 1st-magnitude star. The difficulty will be that Mercury is in a sky bathed in twilight; the brightness of twilight will cause Mercury to look fainter than it really is.

Venus and Mercury will stay out longer after sunset at Earth’s more northerly latitudes. They’ll set sooner after the sun at Earth’s more southerly latitudes. We give the approximate setting times for Mercury and Venus at 60 degrees north latitude, 40 degrees north latitude, equator (0 degrees latitude) and 35 degrees south latitude for the few days around mid-May 2020 (assuming a level horizon):

60 degrees north latitude:
Mercury sets 1 1/2 hours after sunset
Venus sets 4 hours after sunset

40 degrees north latitude
Mercury sets 1 1/6 hours after sunset
Venus sets 2 1/3 hours after sunset

Equator (0 degrees latitude)
Mercury sets less than one hour after sunset
Venus sets less than 2 hours after sunset

35 degrees south latitude
Mercury sets over 1/2 hour after sunset
Venus sets 1 1/3 hours after sunset

Want more specific information? Click here for a recommended sky almanac.

But, as always with sky objects, things will change!

Conjunction of Venus and Mercury around May 20 and 21. Day by day, during the latter half of May 2020, watch for Mercury to set later and for Venus to set sooner after sunset. It’s inevitable that these two worlds will meet up for a conjunction, as Venus sinks into the sunset while Mercury ascends in the western sky. Depending on where you live worldwide, Mercury and Venus will be the closest together on the sky’s dome on May 21 or 22, 2020. These two worlds will be quite close together for several days before – and after – their conjunction. So – for some evenings around May 21 or 22 – take advantage of your opportunity to view both Mercury and Venus in the same binocular (or low-powered telescopic) field of view.

Depending on where you live worldwide, the planets Mercury and Venus will couple up most closely on the sky’s dome on May 21 or May 22, 2020. If you can see Venus, but not Mercury, aim binoculars at Venus to see Mercury and Venus taking stage in a single binocular field of view.

Even in mid-May, however – as Mercury is just beginning its ascent into the western evening sky – you can use Venus (and binoculars) to hop down to Mercury. Seek for Mercury beneath Venus and close to the sunset point on the horizon as evening dusk is giving way to darkness. Mercury is especially bright in mid-May 2020, shining some seven times brighter than a 1st-magnitude star (such as Spica). Mercury is dimming somewhat day by day, and will be shining about 3 times brighter than Spica by the end of the month.

Bottom line: Use dazzling Venus to locate Mercury at dusk in May 2020! It’s the best opportunity of 2020 to spot Mercury in the evening sky. If you live in the Northern Hemisphere, these next few weeks will provide your best view of Mercury’s evening apparition.

from EarthSky https://ift.tt/3cvMazn

Given clear skies and an unobstructed western horizon, the dazzling planet Venus – and the planet Mercury, our sun’s innermost planet – will be yours to behold after sunset from about mid-May 2020 until nearly the end of this month. It’ll be the Northern Hemisphere’s best evening apparition of Mercury; the Southern Hemisphere has a crack at Mercury, too. To find Mercury in mid-May, first look west after sunset for Venus. You can’t miss it. It’s very, very bright in the west after sunset. Next, draw a line with your mind’s eye between Venus and the sunset point. Mercury will be along that line, below Venus, near the sunset point.

Then watch in the coming evenings, as Mercury ascends in the evening sky, while Venus descends toward its June 3 passage between the Earth and sun. The conjunction of Venus and Mercury will come around May 20 and 21.

View at EarthSky Community Photos. | Radu Anghel caught Mercury just after sunset on May 13, 2020, against a bright twilight sky. He wrote: “Mercury is back on the evening sky. On May 22, it will be right next to Venus! :)” Nice catch, Radu! Thanks for posting.

Venus ranks as the third-brightest celestial object to light up the heavens, after the sun and moon. You might see this brilliant beauty of a planet as little as 15 minutes (or less) after sunset. In mid-May – as Mercury is just beginning its ascent into our evening sky – bring binoculars, if you have them, to locate Mercury sooner after sunset in the bright twilight. With binoculars, you might spot Mercury near the sunset point on the horizon some 30 to 45 minutes after sunset.

Although Mercury is nowhere as bright as Venus, Mercury shines more brilliantly than a 1st-magnitude star. The difficulty will be that Mercury is in a sky bathed in twilight; the brightness of twilight will cause Mercury to look fainter than it really is.

Venus and Mercury will stay out longer after sunset at Earth’s more northerly latitudes. They’ll set sooner after the sun at Earth’s more southerly latitudes. We give the approximate setting times for Mercury and Venus at 60 degrees north latitude, 40 degrees north latitude, equator (0 degrees latitude) and 35 degrees south latitude for the few days around mid-May 2020 (assuming a level horizon):

60 degrees north latitude:
Mercury sets 1 1/2 hours after sunset
Venus sets 4 hours after sunset

40 degrees north latitude
Mercury sets 1 1/6 hours after sunset
Venus sets 2 1/3 hours after sunset

Equator (0 degrees latitude)
Mercury sets less than one hour after sunset
Venus sets less than 2 hours after sunset

35 degrees south latitude
Mercury sets over 1/2 hour after sunset
Venus sets 1 1/3 hours after sunset

Want more specific information? Click here for a recommended sky almanac.

But, as always with sky objects, things will change!

Conjunction of Venus and Mercury around May 20 and 21. Day by day, during the latter half of May 2020, watch for Mercury to set later and for Venus to set sooner after sunset. It’s inevitable that these two worlds will meet up for a conjunction, as Venus sinks into the sunset while Mercury ascends in the western sky. Depending on where you live worldwide, Mercury and Venus will be the closest together on the sky’s dome on May 21 or 22, 2020. These two worlds will be quite close together for several days before – and after – their conjunction. So – for some evenings around May 21 or 22 – take advantage of your opportunity to view both Mercury and Venus in the same binocular (or low-powered telescopic) field of view.

Depending on where you live worldwide, the planets Mercury and Venus will couple up most closely on the sky’s dome on May 21 or May 22, 2020. If you can see Venus, but not Mercury, aim binoculars at Venus to see Mercury and Venus taking stage in a single binocular field of view.

Even in mid-May, however – as Mercury is just beginning its ascent into the western evening sky – you can use Venus (and binoculars) to hop down to Mercury. Seek for Mercury beneath Venus and close to the sunset point on the horizon as evening dusk is giving way to darkness. Mercury is especially bright in mid-May 2020, shining some seven times brighter than a 1st-magnitude star (such as Spica). Mercury is dimming somewhat day by day, and will be shining about 3 times brighter than Spica by the end of the month.

Bottom line: Use dazzling Venus to locate Mercury at dusk in May 2020! It’s the best opportunity of 2020 to spot Mercury in the evening sky. If you live in the Northern Hemisphere, these next few weeks will provide your best view of Mercury’s evening apparition.

from EarthSky https://ift.tt/3cvMazn

Submerged in water, this new device uses sunlight to produce energy

Plants use the process of photosynthesis to generate chemical energy from sunlight. Likewise, a new energy-producing device developed at Rice University is triggered by sunlight. Image via Didgeman/ Pixabay.

Rice University researchers have created an efficient, low-cost device that splits water to produce hydrogen fuel.

The device was developed by the Brown School of Engineering lab of Jun Lou, materials scientist at Rice University, and his team. It integrates catalytic electrodes and perovskite solar cells that, when triggered by sunlight, produce electricity. The current flows to the catalysts that split water molecules into hydrogen and oxygen, with a sunlight-to-hydrogen efficiency as high as 6.7%.

Hydrogen can be stored and used as fuel.

This sort of catalysis isn’t new, but the lab packaged a perovskite layer and the electrodes into a single modular unit that, when dropped into water and placed in sunlight, produces hydrogen with no further input.

Here’s what the new device looks like. Cross-sections show the structure of an integrated, solar-powered catalyst that splits water into hydrogen fuel and oxygen. Immersed in water, the device produces fuel when exposed to sunlight. Image via Jia Liang/ Rice University.

The device was described by lead author Lou, postdoctoral fellow Jia Liang and their colleagues in the peer-reviewed journal ACS Nano April 29, 2020. The module is a self-sustaining producer of hydrogen, which can be used for fuel. The researcher say it should be simple to produce in bulk. Lou described the device in a statement:

The concept is broadly similar to an artificial leaf. What we have is an integrated module that turns sunlight into electricity that drives an electrochemical reaction. It utilizes water and sunlight to get chemical fuels.

Perovskites are crystals with cubelike lattices that are known to harvest light. The most efficient perovskite solar cells produced so far achieve an efficiency above 25%, but the materials are expensive and tend to be stressed by light, humidity and heat. Lou said:

Jia has replaced the more expensive components, like platinum, in perovskite solar cells with alternatives like carbon. That lowers the entry barrier for commercial adoption. Integrated devices like this are promising because they create a system that is sustainable. This does not require any external power to keep the module running.

The key component may not be the perovskite but the polymer that encapsulates it, protecting the module and allowing to be immersed for long periods, Liang said.

Others have developed catalytic systems that connect the solar cell outside the water to immersed electrodes with a wire. We simplify the system by encapsulating the perovskite layer with a Surlyn (polymer) film.

The patterned film allows sunlight to reach the solar cell while protecting it and serves as an insulator between the cells and the electrodes, Liang said. Lou added:

With a clever system design, you can potentially make a self-sustaining loop. Even when there’s no sunlight, you can use stored energy in the form of chemical fuel. You can put the hydrogen and oxygen products in separate tanks and incorporate another module like a fuel cell to turn those fuels back into electricity.

The researchers said they will continue to improve the encapsulation technique as well as the solar cells themselves to raise the efficiency of the modules.

Bottom line: Rice University researchers have designed a device which, when immersed in water and exposed to sunlight, generates hydrogen and oxygen.

Source: A Low-Cost and High-Efficiency Integrated Device toward Solar-Driven Water Splitting

Via Rice University

from EarthSky https://ift.tt/2Z1ns6f

Plants use the process of photosynthesis to generate chemical energy from sunlight. Likewise, a new energy-producing device developed at Rice University is triggered by sunlight. Image via Didgeman/ Pixabay.

Rice University researchers have created an efficient, low-cost device that splits water to produce hydrogen fuel.

The device was developed by the Brown School of Engineering lab of Jun Lou, materials scientist at Rice University, and his team. It integrates catalytic electrodes and perovskite solar cells that, when triggered by sunlight, produce electricity. The current flows to the catalysts that split water molecules into hydrogen and oxygen, with a sunlight-to-hydrogen efficiency as high as 6.7%.

Hydrogen can be stored and used as fuel.

This sort of catalysis isn’t new, but the lab packaged a perovskite layer and the electrodes into a single modular unit that, when dropped into water and placed in sunlight, produces hydrogen with no further input.

Here’s what the new device looks like. Cross-sections show the structure of an integrated, solar-powered catalyst that splits water into hydrogen fuel and oxygen. Immersed in water, the device produces fuel when exposed to sunlight. Image via Jia Liang/ Rice University.

The device was described by lead author Lou, postdoctoral fellow Jia Liang and their colleagues in the peer-reviewed journal ACS Nano April 29, 2020. The module is a self-sustaining producer of hydrogen, which can be used for fuel. The researcher say it should be simple to produce in bulk. Lou described the device in a statement:

The concept is broadly similar to an artificial leaf. What we have is an integrated module that turns sunlight into electricity that drives an electrochemical reaction. It utilizes water and sunlight to get chemical fuels.

Perovskites are crystals with cubelike lattices that are known to harvest light. The most efficient perovskite solar cells produced so far achieve an efficiency above 25%, but the materials are expensive and tend to be stressed by light, humidity and heat. Lou said:

Jia has replaced the more expensive components, like platinum, in perovskite solar cells with alternatives like carbon. That lowers the entry barrier for commercial adoption. Integrated devices like this are promising because they create a system that is sustainable. This does not require any external power to keep the module running.

The key component may not be the perovskite but the polymer that encapsulates it, protecting the module and allowing to be immersed for long periods, Liang said.

Others have developed catalytic systems that connect the solar cell outside the water to immersed electrodes with a wire. We simplify the system by encapsulating the perovskite layer with a Surlyn (polymer) film.

The patterned film allows sunlight to reach the solar cell while protecting it and serves as an insulator between the cells and the electrodes, Liang said. Lou added:

With a clever system design, you can potentially make a self-sustaining loop. Even when there’s no sunlight, you can use stored energy in the form of chemical fuel. You can put the hydrogen and oxygen products in separate tanks and incorporate another module like a fuel cell to turn those fuels back into electricity.

The researchers said they will continue to improve the encapsulation technique as well as the solar cells themselves to raise the efficiency of the modules.

Bottom line: Rice University researchers have designed a device which, when immersed in water and exposed to sunlight, generates hydrogen and oxygen.

Source: A Low-Cost and High-Efficiency Integrated Device toward Solar-Driven Water Splitting

Via Rice University

from EarthSky https://ift.tt/2Z1ns6f

Coronavirus reports – Part 2: “We’re ahead when it comes to isolation”

We caught up with people living with cancer across the country, to find out how isolation due to the pandemic has been affecting them and their families. 

Amber: “It’s a bit of a kick in the teeth” 

“I was planning to return to university in September, I have changed my course to do Drama and English Lit as

it is more line with what I want to do, but I am not sure if that will happen now in September with all that is going on.”  

Amber was diagnosed with acute lymphoblastic leukaemia in August 2019. During her intensive phase of her treatment, she was

Amber, diagnosed with acute lymphoblastic leukaemia in August 2019

in isolation, and had been due to start her maintenance treatment in March 2020 but it was slightly postponed due to a slow recovery.   

After the government announced the COVID-19 shielding measures, Amber was advised to continue isolating until mid-June. Despite isolation, she’s still going to hospital appointments.  

“I am coming to the hospital quite a bit at the moment. I had to have some blood transfusions recently and also for these tests too. I am collected in a car to take me to and from the hospital. We are given masks to wear, so they are trying to take precautions to reduce the risk.”  

She feels as though her experience last year has prepared her for this phase of isolation and is taking time to bounce back from the weight gained during her treatment. Aside from using a FitBit to track her exercise and taking part in online fitness classes, she also understands the importance of mental health.  

“After nine months of not being able to do much, it is a bit of a kick in the teeth to have to now self-isolate for another 12 weeks. But in some ways, I guess I am more equipped to deal with this than most people. I think it is really important to look after your mental health during this time. I like to do creative writing and doodling to keep me occupied.” 

 Thea: “We’re being asked to protect our loved ones”  

“I’ve experienced isolation before. But it was very, very different to this. It was very clinical, very scary, and there were no luxuries. I was in a room that was about three metres by three metres. The day I was ‘checked’ into that room, I didn’t know whether I was going to come out of that room. I didn’t know if I would live or die”  

Thea on a bike ride.

Living in Shropshire, Thea was diagnosed with a rare subtype of acute myeloid leukaemia in December 2014. During her treatment, she found herself having to isolate in cramped conditions attached to machines giving her life saving drugs and chemotherapy so – to her – this period of isolation is far better.

“For me, it’s five star, I have the freedom to leave that three metre by three metre room, and take my hours exercise. I have the freedom to make a cup of tea when I want a cup of tea. I have the freedom to make choices.”  

Being so close to open green spaces, she’s able to regularly take daily runs with her dog and keeps in touch with friends online, things she was unable to do during her previous isolation. From her perspective, she’s helping her community.  

“We’re doing it because we’re protecting our villages, our towns, our counties, our country, our nation.  This is a global effort. This isn’t just one person doing something. This is the whole world. Soon we will all be able to live our ‘new normal’ lives again.” 

Dylan and Siobhan: “We’re ahead when it comes to isolation” 

“The last three and a half years have put us ahead when it comes to isolation. We are used not to having choices and freedom.” 

Siobhan and Dylan.

In December 2016, Siobhan’s son Dylan was diagnosed with a type of non-Hodgkin lymphoma known as B-cell

Lymphoblastic lymphoma. Although Dylan’s treatment finished in March, Siobhan says it’s still a stressful time. Dylan’s treatment has left him with no immune system and Siobhan is constantly looking out for any sign of relapse. She’s aware that any exposure to the virus, be it in a public space or at a hospital, could be life-threatening. 

“Dylan has been out of the house four times over the whole time, and always just to walk around the block – we are usually back home inside in about seven minutes!” 

Despite Dylan’s inability to get out, Siobhan makes use of her daily exercise time to clear her head. She maintains that the biggest difference between this and Dylan’s last experience of isolation is what’s happening in the outside world. 

“I am watching people dealing with this current situation and have been fascinated and flabbergasted by people who have not understood the seriousness of it. The lockdown is only going to be temporary for most. But you can’t overstate how important it is to help people like Dylan to get this under control.” 

Clare: “Mum has struggled the most” 

Clare was diagnosed with endometrial cancer in 2013 and has gone through radiotherapy, chemotherapy and brachytherapy – a form of internal radiation. Even before the government officially announced the lockdown, her doctor phoned her to tell her she needed to shield.    

“It’s the 10th week for us now.”

Clare’s friends have been dropping things off at her house and, aside from sneaking out in the early hours of the morning one day to give them Easter treats, she’s been staying at home. 

However, it’s not just Clare. Both her mum and her dad, who was given the all clear in 2013 from his own cancer treatment, are having to shield. Clare says that her mum has struggled the most with this experience as “she was the most independent of us”.  

Clare’s been spending some of her time at home helping others, by providing online support for people in the cancer community. “There is a fear that people are going to die and not get the treatments they need. People are really worried.”

Alex

Read more about the experience of people living with cancer and how the pandemic has affected their treatments.

from Cancer Research UK – Science blog https://ift.tt/3bAfsvn

We caught up with people living with cancer across the country, to find out how isolation due to the pandemic has been affecting them and their families. 

Amber: “It’s a bit of a kick in the teeth” 

“I was planning to return to university in September, I have changed my course to do Drama and English Lit as

it is more line with what I want to do, but I am not sure if that will happen now in September with all that is going on.”  

Amber was diagnosed with acute lymphoblastic leukaemia in August 2019. During her intensive phase of her treatment, she was

Amber, diagnosed with acute lymphoblastic leukaemia in August 2019

in isolation, and had been due to start her maintenance treatment in March 2020 but it was slightly postponed due to a slow recovery.   

After the government announced the COVID-19 shielding measures, Amber was advised to continue isolating until mid-June. Despite isolation, she’s still going to hospital appointments.  

“I am coming to the hospital quite a bit at the moment. I had to have some blood transfusions recently and also for these tests too. I am collected in a car to take me to and from the hospital. We are given masks to wear, so they are trying to take precautions to reduce the risk.”  

She feels as though her experience last year has prepared her for this phase of isolation and is taking time to bounce back from the weight gained during her treatment. Aside from using a FitBit to track her exercise and taking part in online fitness classes, she also understands the importance of mental health.  

“After nine months of not being able to do much, it is a bit of a kick in the teeth to have to now self-isolate for another 12 weeks. But in some ways, I guess I am more equipped to deal with this than most people. I think it is really important to look after your mental health during this time. I like to do creative writing and doodling to keep me occupied.” 

 Thea: “We’re being asked to protect our loved ones”  

“I’ve experienced isolation before. But it was very, very different to this. It was very clinical, very scary, and there were no luxuries. I was in a room that was about three metres by three metres. The day I was ‘checked’ into that room, I didn’t know whether I was going to come out of that room. I didn’t know if I would live or die”  

Thea on a bike ride.

Living in Shropshire, Thea was diagnosed with a rare subtype of acute myeloid leukaemia in December 2014. During her treatment, she found herself having to isolate in cramped conditions attached to machines giving her life saving drugs and chemotherapy so – to her – this period of isolation is far better.

“For me, it’s five star, I have the freedom to leave that three metre by three metre room, and take my hours exercise. I have the freedom to make a cup of tea when I want a cup of tea. I have the freedom to make choices.”  

Being so close to open green spaces, she’s able to regularly take daily runs with her dog and keeps in touch with friends online, things she was unable to do during her previous isolation. From her perspective, she’s helping her community.  

“We’re doing it because we’re protecting our villages, our towns, our counties, our country, our nation.  This is a global effort. This isn’t just one person doing something. This is the whole world. Soon we will all be able to live our ‘new normal’ lives again.” 

Dylan and Siobhan: “We’re ahead when it comes to isolation” 

“The last three and a half years have put us ahead when it comes to isolation. We are used not to having choices and freedom.” 

Siobhan and Dylan.

In December 2016, Siobhan’s son Dylan was diagnosed with a type of non-Hodgkin lymphoma known as B-cell

Lymphoblastic lymphoma. Although Dylan’s treatment finished in March, Siobhan says it’s still a stressful time. Dylan’s treatment has left him with no immune system and Siobhan is constantly looking out for any sign of relapse. She’s aware that any exposure to the virus, be it in a public space or at a hospital, could be life-threatening. 

“Dylan has been out of the house four times over the whole time, and always just to walk around the block – we are usually back home inside in about seven minutes!” 

Despite Dylan’s inability to get out, Siobhan makes use of her daily exercise time to clear her head. She maintains that the biggest difference between this and Dylan’s last experience of isolation is what’s happening in the outside world. 

“I am watching people dealing with this current situation and have been fascinated and flabbergasted by people who have not understood the seriousness of it. The lockdown is only going to be temporary for most. But you can’t overstate how important it is to help people like Dylan to get this under control.” 

Clare: “Mum has struggled the most” 

Clare was diagnosed with endometrial cancer in 2013 and has gone through radiotherapy, chemotherapy and brachytherapy – a form of internal radiation. Even before the government officially announced the lockdown, her doctor phoned her to tell her she needed to shield.    

“It’s the 10th week for us now.”

Clare’s friends have been dropping things off at her house and, aside from sneaking out in the early hours of the morning one day to give them Easter treats, she’s been staying at home. 

However, it’s not just Clare. Both her mum and her dad, who was given the all clear in 2013 from his own cancer treatment, are having to shield. Clare says that her mum has struggled the most with this experience as “she was the most independent of us”.  

Clare’s been spending some of her time at home helping others, by providing online support for people in the cancer community. “There is a fear that people are going to die and not get the treatments they need. People are really worried.”

Alex

Read more about the experience of people living with cancer and how the pandemic has affected their treatments.

from Cancer Research UK – Science blog https://ift.tt/3bAfsvn

This brown dwarf might look a lot like Jupiter

The quality of mass is what separates planets from brown dwarfs from stars. Here’s a general comparison of the masses of each. Image via NASA/ Caltech/ R. Hurt (IPAC).

Scientists studying the closest-known brown dwarf – an object much heavier than a planet but lighter than a star – have found that it has bands of clouds reminiscent of those on our solar system’s largest planet, Jupiter. As reported by Caltech, while evidence for cloud bands on brown dwarfs has been seen before, this discovery represents the first time that these features have been inferred using an observing technique known as polarimetry. The researchers used the NaCo instrument on the Very Large Telescope (VLT) in Chile to make the discovery.

The peer-reviewed findings were published in The Astrophysical Journal on May 5, 2020.

Polarimetry works in a way related to the way polarized sunglasses block out bright sunlight. Maxwell Millar-Blanchaer, a scientist at Caltech and lead author of the new study, said in a statement:

I often think of polarimetric instruments as an astronomer’s polarized sunglasses. But instead of trying to block out that glare we’re trying to measure it.

Of course, we don’t really know what brown dwarfs look like. They’re far away, and we’ve never seen one up close. But here’s an artist’s concept of the brown dwarf called Luhman 16A, basd on recent evidence of Jupiter-like bands on its surface. Image via Caltech/ R. Hurt (IPAC).

Astronomer Dimitri Mawet, also of Caltech, described the use of polarimetry this way:

Polarimetry is receiving renewed attention in astronomy. Polarimetry is a very difficult art, but new techniques and data analysis methods make it more precise and sensitive than ever before, enabling groundbreaking studies on everything from distant supermassive black holes, newborn and dying stars, brown dwarfs, and exoplanets, all the way down to objects in our own solar system.

The brown dwarf Luhman 16A is actually one of a pair of brown dwarfs in a binary system, similar to a system of binary stars. It is the closest such system known, only 6.5 light-years away from Earth. Each brown dwarf in this system is similar in size to Jupiter, but 30 times more massive. Both have similar temperatures of about 1,900 degrees Fahrenheit (1,000 degrees Celsius).

Scientists had previously found evidence for patchy clouds on the other brown dwarf of the pair, Luhman 16B, but not bands. How and why the other brown dwarf may be different is as yet unknown. Study co-author Julien Girard of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, said:

Like Earth and Venus, these objects are twins with very different weather.

The researchers ruled out other possibilities before determining that Luhman 16A really did have a banded atmosphere. Theodora Karalidi of the University of Central Florida in Orlando, Florida, said:

To determine what the light encountered on its way [from the brown dwarf to Earth], we compared observations against models with different properties: brown dwarf atmospheres with solid cloud decks, striped cloud bands, and even brown dwarfs that are oblate due to their fast rotation. We found that only models of atmospheres with cloud bands could match our observations of Luhman 16A.

NASA’s Spitzer Space Telescope previously found banding on three other brown dwarfs. The difference between all the previous observations and the new one is that the old measured changing brightness but not polarized light.

This time, though, NaCo observed polarized light from both of the Luhman brown dwarfs. Millar-Blanchaer said:

Polarimetry is the only technique that is currently able to detect bands that don’t fluctuate in brightness over time. This was key to finding the bands of clouds on Luhman 16A, on which the bands do not appear to be varying.

Jupiter as seen by NASA’s Juno spacecraft on April 1, 2018. How much more detail would we see in Luhman 16A, if we could see it up close like this? Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ Gerald Eichstäd/ Seán Doran © CC NC SA.

Polarimetry doesn’t image the brown dwarfs per se, but rather simply measures the amount of polarized light they emit. Scientists then use atmospheric modeling to infer the presence of the cloud bands.

Right now, scientists don’t know how many bands there are on Luhman 16A, but the data suggest at least two.

On Luhman 16A’s brother brown dwarf – Luhman 16B – the study shows that the cloud patches are probably very active and stormy, similar to storms on Jupiter. According to Girard:

We think these storms can rain things like silicates or ammonia. It’s pretty awful weather, actually.

Brown dwarfs are enigmatic objects; they are often referred to as failed stars, since they don’t have enough mass to ignite and shine as full-fledged stars. But they are also more massive than any known planets. They’re sometimes referred to as hybrid objects, between large planets and small stars.

Brown dwarfs are not the only objects that can be studied with polarimetry. The technique is also useful for observing exoplanets – planets orbiting other stars – especially giant, hot planets like hot Jupiters. It’s not easy, though, since hot Jupiters orbit very close to their stars, and so are relatively faint. Other planets are even fainter.

Maxwell Millar-Blanchaer at Caltech, lead author of the new study. Image via Caltech.

Millar-Blanchaer said:

Polarimetry is very sensitive to cloud properties, both in brown dwarfs and exoplanets. This is the first time that it’s really been exploited to understand cloud properties outside of the solar system.

According to Millar-Blanchaer, polarimetry is sensitive enough that it might even be able to detect surface liquid water on exoplanets. Now that would be exciting!

NASA’s upcoming James Webb Space Telescope (JWST) and Wide Field Infrared Survey Telescope (WFIRST) will also be able to observe brown dwarfs like Luhman 16A and look for signs of clouds. WFIRST will be equipped with a coronagraph instrument to conduct polarimetry, and may even be able to detect giant exoplanets in reflected light, as well as evidence of clouds in their atmospheres. With missions like these in the near future, scientists will be able to learn much more about brown dwarfs and their variously decorated atmospheres.

Bottom line: Scientists have found evidence of banded clouds on one of the two closest brown dwarfs.

Source: Detection of Polarization due to Cloud Bands in the Nearby Luhman 16 Brown Dwarf Binary

Via Caltech

Via Hubblesite

from EarthSky https://ift.tt/2Ws6QCZ

The quality of mass is what separates planets from brown dwarfs from stars. Here’s a general comparison of the masses of each. Image via NASA/ Caltech/ R. Hurt (IPAC).

Scientists studying the closest-known brown dwarf – an object much heavier than a planet but lighter than a star – have found that it has bands of clouds reminiscent of those on our solar system’s largest planet, Jupiter. As reported by Caltech, while evidence for cloud bands on brown dwarfs has been seen before, this discovery represents the first time that these features have been inferred using an observing technique known as polarimetry. The researchers used the NaCo instrument on the Very Large Telescope (VLT) in Chile to make the discovery.

The peer-reviewed findings were published in The Astrophysical Journal on May 5, 2020.

Polarimetry works in a way related to the way polarized sunglasses block out bright sunlight. Maxwell Millar-Blanchaer, a scientist at Caltech and lead author of the new study, said in a statement:

I often think of polarimetric instruments as an astronomer’s polarized sunglasses. But instead of trying to block out that glare we’re trying to measure it.

Of course, we don’t really know what brown dwarfs look like. They’re far away, and we’ve never seen one up close. But here’s an artist’s concept of the brown dwarf called Luhman 16A, basd on recent evidence of Jupiter-like bands on its surface. Image via Caltech/ R. Hurt (IPAC).

Astronomer Dimitri Mawet, also of Caltech, described the use of polarimetry this way:

Polarimetry is receiving renewed attention in astronomy. Polarimetry is a very difficult art, but new techniques and data analysis methods make it more precise and sensitive than ever before, enabling groundbreaking studies on everything from distant supermassive black holes, newborn and dying stars, brown dwarfs, and exoplanets, all the way down to objects in our own solar system.

The brown dwarf Luhman 16A is actually one of a pair of brown dwarfs in a binary system, similar to a system of binary stars. It is the closest such system known, only 6.5 light-years away from Earth. Each brown dwarf in this system is similar in size to Jupiter, but 30 times more massive. Both have similar temperatures of about 1,900 degrees Fahrenheit (1,000 degrees Celsius).

Scientists had previously found evidence for patchy clouds on the other brown dwarf of the pair, Luhman 16B, but not bands. How and why the other brown dwarf may be different is as yet unknown. Study co-author Julien Girard of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, said:

Like Earth and Venus, these objects are twins with very different weather.

The researchers ruled out other possibilities before determining that Luhman 16A really did have a banded atmosphere. Theodora Karalidi of the University of Central Florida in Orlando, Florida, said:

To determine what the light encountered on its way [from the brown dwarf to Earth], we compared observations against models with different properties: brown dwarf atmospheres with solid cloud decks, striped cloud bands, and even brown dwarfs that are oblate due to their fast rotation. We found that only models of atmospheres with cloud bands could match our observations of Luhman 16A.

NASA’s Spitzer Space Telescope previously found banding on three other brown dwarfs. The difference between all the previous observations and the new one is that the old measured changing brightness but not polarized light.

This time, though, NaCo observed polarized light from both of the Luhman brown dwarfs. Millar-Blanchaer said:

Polarimetry is the only technique that is currently able to detect bands that don’t fluctuate in brightness over time. This was key to finding the bands of clouds on Luhman 16A, on which the bands do not appear to be varying.

Jupiter as seen by NASA’s Juno spacecraft on April 1, 2018. How much more detail would we see in Luhman 16A, if we could see it up close like this? Image via NASA/ JPL-Caltech/ SwRI/ MSSS/ Gerald Eichstäd/ Seán Doran © CC NC SA.

Polarimetry doesn’t image the brown dwarfs per se, but rather simply measures the amount of polarized light they emit. Scientists then use atmospheric modeling to infer the presence of the cloud bands.

Right now, scientists don’t know how many bands there are on Luhman 16A, but the data suggest at least two.

On Luhman 16A’s brother brown dwarf – Luhman 16B – the study shows that the cloud patches are probably very active and stormy, similar to storms on Jupiter. According to Girard:

We think these storms can rain things like silicates or ammonia. It’s pretty awful weather, actually.

Brown dwarfs are enigmatic objects; they are often referred to as failed stars, since they don’t have enough mass to ignite and shine as full-fledged stars. But they are also more massive than any known planets. They’re sometimes referred to as hybrid objects, between large planets and small stars.

Brown dwarfs are not the only objects that can be studied with polarimetry. The technique is also useful for observing exoplanets – planets orbiting other stars – especially giant, hot planets like hot Jupiters. It’s not easy, though, since hot Jupiters orbit very close to their stars, and so are relatively faint. Other planets are even fainter.

Maxwell Millar-Blanchaer at Caltech, lead author of the new study. Image via Caltech.

Millar-Blanchaer said:

Polarimetry is very sensitive to cloud properties, both in brown dwarfs and exoplanets. This is the first time that it’s really been exploited to understand cloud properties outside of the solar system.

According to Millar-Blanchaer, polarimetry is sensitive enough that it might even be able to detect surface liquid water on exoplanets. Now that would be exciting!

NASA’s upcoming James Webb Space Telescope (JWST) and Wide Field Infrared Survey Telescope (WFIRST) will also be able to observe brown dwarfs like Luhman 16A and look for signs of clouds. WFIRST will be equipped with a coronagraph instrument to conduct polarimetry, and may even be able to detect giant exoplanets in reflected light, as well as evidence of clouds in their atmospheres. With missions like these in the near future, scientists will be able to learn much more about brown dwarfs and their variously decorated atmospheres.

Bottom line: Scientists have found evidence of banded clouds on one of the two closest brown dwarfs.

Source: Detection of Polarization due to Cloud Bands in the Nearby Luhman 16 Brown Dwarf Binary

Via Caltech

Via Hubblesite

from EarthSky https://ift.tt/2Ws6QCZ

Venus is waning! Here are some photos

View at EarthSky Community Photos. | Some people are surprised to learn that Venus sometimes appears as a crescent, from our earthly vantage point. But, indeed, it does. Eliot Herman in Tucson, Arizona, captured an image of Venus (left, inset) on May 13, 2020, and contrasted it, in this montage, with a photo of a crescent moon (right). Thank you, Eliot!

View at EarthSky Community Photos. | Victor C. Rogus of Sedona, Arizona, caught Venus as a waning crescent on May 11, 2020. He wrote: “It is becoming thinner!” Indeed, it is. And Venus will continue to wane in phase for the rest of this month, as it drops closer and closer to the sunset each evening. It will finally go between us and the sun on June 3, afterwards re-emerging into the morning sky. Thank you, Victor!

You can see Venus now in the west after sunset each evening. To the eye alone, it looks like an extremely bright point of light. Steadily held binoculars might show it as something other than round. This chart by Guy Ottewell (via his blog) depicts Venus’ disk size and phase – best seen through a telescope – in the evening sky from the planet’s superior conjunction (August 14, 2019, when it was on the far side of the sun from us) to inferior conjunction (June 3, 2020, when it’ll pass between us and the sun).

View at EarthSky Community Photos. | Aurelian Neacsu in Visina, Dambovita County, Romania, caught Venus as a 15.9% illuminated crescent on May 10, 2020. Thank you, Aurelian.

View larger at EarthSky Community Photos. | Dion Rust – Subsonic0 (@trent900uk on Twitter) – posted this beautiful crescent Venus photo to EarthSky’s Twitter feed. Dion wrote: “Managed a quick snap of it last week. It’s a lovely crescent at the moment so if anyone can have a look it’s worth it.” It was taken May 7, 2020, from East Hertfordshire, U.K. Thanks, Dion!

Why does Venus look like a crescent now? Just before and after superior conjunction last August – when Venus swept behind the sun from Earth – we saw a nearly full Venus. Inferior conjunction – when Venus will sweep between us and the sun – will happen next on June 3, 2020. Just before and after, we see a crescent Venus. Image via UCLA.

Bottom line: Photos of Venus in a waning crescent phase from the EarthSky Community, plus a diagram showing the phases of Venus during its evening apparition of late 2019 and early 2020, and, also, a diagram illustrating why Venus changes in phase.

from EarthSky https://ift.tt/366GEkF

View at EarthSky Community Photos. | Some people are surprised to learn that Venus sometimes appears as a crescent, from our earthly vantage point. But, indeed, it does. Eliot Herman in Tucson, Arizona, captured an image of Venus (left, inset) on May 13, 2020, and contrasted it, in this montage, with a photo of a crescent moon (right). Thank you, Eliot!

View at EarthSky Community Photos. | Victor C. Rogus of Sedona, Arizona, caught Venus as a waning crescent on May 11, 2020. He wrote: “It is becoming thinner!” Indeed, it is. And Venus will continue to wane in phase for the rest of this month, as it drops closer and closer to the sunset each evening. It will finally go between us and the sun on June 3, afterwards re-emerging into the morning sky. Thank you, Victor!

You can see Venus now in the west after sunset each evening. To the eye alone, it looks like an extremely bright point of light. Steadily held binoculars might show it as something other than round. This chart by Guy Ottewell (via his blog) depicts Venus’ disk size and phase – best seen through a telescope – in the evening sky from the planet’s superior conjunction (August 14, 2019, when it was on the far side of the sun from us) to inferior conjunction (June 3, 2020, when it’ll pass between us and the sun).

View at EarthSky Community Photos. | Aurelian Neacsu in Visina, Dambovita County, Romania, caught Venus as a 15.9% illuminated crescent on May 10, 2020. Thank you, Aurelian.

View larger at EarthSky Community Photos. | Dion Rust – Subsonic0 (@trent900uk on Twitter) – posted this beautiful crescent Venus photo to EarthSky’s Twitter feed. Dion wrote: “Managed a quick snap of it last week. It’s a lovely crescent at the moment so if anyone can have a look it’s worth it.” It was taken May 7, 2020, from East Hertfordshire, U.K. Thanks, Dion!

Why does Venus look like a crescent now? Just before and after superior conjunction last August – when Venus swept behind the sun from Earth – we saw a nearly full Venus. Inferior conjunction – when Venus will sweep between us and the sun – will happen next on June 3, 2020. Just before and after, we see a crescent Venus. Image via UCLA.

Bottom line: Photos of Venus in a waning crescent phase from the EarthSky Community, plus a diagram showing the phases of Venus during its evening apparition of late 2019 and early 2020, and, also, a diagram illustrating why Venus changes in phase.

from EarthSky https://ift.tt/366GEkF