August 5, 2017

The ESO 338-4 Galaxy

The ESO 338-4 Galaxy

ESO 338-4 is a starburst galaxy located in Sagittarius, the Archer. It is currently in the process of merging, with several smaller galaxies colliding to form the final galaxy. The new AOF+MUSE data clearly resolve several bright knots where intense star formation, induced by the merging, is occurring, as well as filaments of glowing hydrogen gas.

Image Credit: ESO/P. Weilbacher
Explanation from: https://www.eso.org/public/images/eso1724i/

Saturn's Rings

Saturn's Rings

Saturn's icy rings shine in scattered sunlight in this view, which looks toward the unilluminated northern side of the rings from about 15 degrees above the ringplane.

The Sun currently illuminates the rings from the south. Some of the sunlight not reflected from the rings' southern face is scattered through the countless particles, setting the rings aglow.

The inner F-ring shepherd moon Prometheus (86 kilometers, or 53 miles across at its widest point) appears at lower left.

Images taken using red, green and blue spectral filters were combined to create this natural color view. Bright clumps of material in the narrow F ring moved in their orbits between each of the color exposures, creating a chromatic misalignment in several places that provides some sense of the continuous motion within the ring system.

The images were obtained with the Cassini spacecraft wide-angle camera on July 4, 2008 at a distance of approximately 1.2 million kilometers (770,000 miles) from Saturn. The Sun-ring-spacecraft, or phase, angle was 28 degrees. Image scale is 70 kilometers (44 miles) per pixel.

Image Credit: NASA/JPL/Space Science Institute
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA10446

Exoplanet GJ 1214b

Exoplanet GJ 1214b

This artist’s impression shows the super-Earth exoplanet GJ 1214b passing in front of its faint red parent star. This is the first super-Earth exoplanet to have had its atmosphere analysed. The exoplanet, orbiting a small star only 40 light-years away from us, has a mass about six times that of the Earth. GJ 1214b appears to be surrounded by an atmosphere that is either dominated by steam or blanketed by thick clouds or hazes.

Image Credit: ESO/L. Calçada
Explanation from: https://www.eso.org/public/images/eso1047b/

August 4, 2017

Planetary Nebula NGC 6369

Planetary Nebula NGC 6369

Known as the Little Ghost Nebula, NGC 6369 is a planetary nebula in the constellation Ophiuchus, the serpent-bearer. The nebula is relatively faint with an apparent magnitude of 12.9 and the clear detail of this image shows the power of the AOF-equipped MUSE instrument of the VLT. The white dwarf star is clearly visible in the middle of the nebular gas, which is expanding out in rings.

Image Credit: ESO/P. Weilbacher (AIP)
Explanation from: https://www.eso.org/public/images/eso1724h/

Exoplanet WASP-121b

Exoplanet WASP-121b

This is an artist’s impression of the gas giant exoplanet WASP-121b. The bloated planet is so close to its star that the tidal pull of the star stretches it into an egg shape. The top of the planet's atmosphere is heated to a blazing 2500 degrees Celsius, hot enough to boil iron. This is the first planet outside our Solar System where astronomers have found the strongest evidence yet for a stratosphere — a layer of atmosphere in which temperature increases with higher altitudes. The planet is about 900 light-years away.

Image Credit: NASA, ESA, and G. Bacon (STScI)
Explanation from: https://www.spacetelescope.org/images/opo1731a/

Jupiter Storm of the High North

Jupiter Storm of the High North

A dynamic storm at the southern edge of Jupiter's northern polar region dominates this Jovian cloudscape, courtesy of NASA's Juno spacecraft.

This storm is a long-lived anticyclonic oval named North North Temperate Little Red Spot 1 (NN-LRS-1); it has been tracked at least since 1993, and may be older still. An anticyclone is a weather phenomenon where winds around the storm flow in the direction opposite to that of the flow around a region of low pressure. It is the third largest anticyclonic oval on the planet, typically around 3,700 miles (6,000 kilometers) long. The color varies between red and off-white (as it is now), but this JunoCam image shows that it still has a pale reddish core within the radius of maximum wind speeds.

Citizen scientists Gerald Eichstädt and Seán Doran processed this image using data from the JunoCam imager. The image has been rotated so that the top of the image is actually the equatorial regions while the bottom of the image is of the northern polar regions of the planet.

The image was taken on July 10, 2017 at 6:42 p.m. PDT (9:42 p.m. EDT), as the Juno spacecraft performed its seventh close flyby of Jupiter. At the time the image was taken, the spacecraft was about 7,111 miles (11,444 kilometers) from the tops of the clouds of the planet at a latitude of 44.5 degrees.

Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstadt/Sean Doran
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21776

August 3, 2017

Earth's Atmosphere seen from the International Space Station

Earth's Atmosphere seen from the International Space Station

The thin line of Earth's atmosphere and the blackness of space are featured in this image photographed by an Expedition 24 crew member on the International Space Station.

Image Credit: NASA

Hubble Detects Exoplanet with Glowing Water Atmosphere

This artist's concept shows hot Jupiter WASP-121b, which presents the best evidence yet of a stratosphere on an exoplanet.

Scientists have discovered the strongest evidence to date for a stratosphere on a planet outside our solar system, or exoplanet. A stratosphere is a layer of atmosphere in which temperature increases with higher altitudes.

"This result is exciting because it shows that a common trait of most of the atmospheres in our solar system -- a warm stratosphere -- also can be found in exoplanet atmospheres," said Mark Marley, study co-author based at NASA's Ames Research Center in California's Silicon Valley. "We can now compare processes in exoplanet atmospheres with the same processes that happen under different sets of conditions in our own solar system."

Reporting in the journal Nature, scientists used data from NASA's Hubble Space Telescope to study WASP-121b, a type of exoplanet called a "hot Jupiter." Its mass is 1.2 times that of Jupiter, and its radius is about 1.9 times Jupiter's -- making it puffier. But while Jupiter revolves around our sun once every 12 years, WASP-121b has an orbital period of just 1.3 days. This exoplanet is so close to its star that if it got any closer, the star's gravity would start ripping it apart. It also means that the top of the planet's atmosphere is heated to a blazing 4,600 degrees Fahrenheit (2,500 Celsius), hot enough to boil some metals. The WASP-121 system is estimated to be about 900 light years from Earth – a long way, but close by galactic standards.

Previous research found possible signs of a stratosphere on the exoplanet WASP-33b as well as some other hot Jupiters. The new study presents the best evidence yet because of the signature of hot water molecules that researchers observed for the first time.

“Theoretical models have suggested stratospheres may define a distinct class of ultra-hot planets, with important implications for their atmospheric physics and chemistry,” said Tom Evans, lead author and research fellow at the University of Exeter, United Kingdom. “Our observations support this picture.”

To study the stratosphere of WASP-121b, scientists analyzed how different molecules in the atmosphere react to particular wavelengths of light, using Hubble's capabilities for spectroscopy. Water vapor in the planet's atmosphere, for example, behaves in predictable ways in response to certain wavelengths of light, depending on the temperature of the water.

Starlight is able to penetrate deep into a planet's atmosphere, where it raises the temperature of the gas there. This gas then radiates its heat into space as infrared light. However, if there is cooler water vapor at the top of the atmosphere, the water molecules will prevent certain wavelengths of this light from escaping to space. But if the water molecules at the top of the atmosphere have a higher temperature, they will glow at the same wavelengths.

"The emission of light from water means the temperature is increasing with height," said Tiffany Kataria, study co-author based at NASA's Jet Propulsion Laboratory, Pasadena, California. "We're excited to explore at what longitudes this behavior persists with upcoming Hubble observations."

The phenomenon is similar to what happens with fireworks, which get their colors from chemicals emitting light. When metallic substances are heated and vaporized, their electrons move into higher energy states. Depending on the material, these electrons will emit light at specific wavelengths as they lose energy: sodium produces orange-yellow and strontium produces red in this process, for example. The water molecules in the atmosphere of WASP-121b similarly give off radiation as they lose energy, but in the form of infrared light, which the human eye is unable to detect.

In Earth's stratosphere, ozone gas traps ultraviolet radiation from the sun, which raises the temperature of this layer of atmosphere. Other solar system bodies have stratospheres, too; methane is responsible for heating in the stratospheres of Jupiter and Saturn's moon Titan, for example.

In solar system planets, the change in temperature within a stratosphere is typically around 100 degrees Fahrenheit (about 56 degrees Celsius). On WASP-121b, the temperature in the stratosphere rises by 1,000 degrees (560 degrees Celsius). Scientists do not yet know what chemicals are causing the temperature increase in WASP-121b's atmosphere. Vanadium oxide and titanium oxide are candidates, as they are commonly seen in brown dwarfs, "failed stars" that have some commonalities with exoplanets. Such compounds are expected to be present only on the hottest of hot Jupiters, as high temperatures are needed to keep them in a gaseous state.

"This super-hot exoplanet is going to be a benchmark for our atmospheric models, and it will be a great observational target moving into the Webb era," said Hannah Wakeford, study co-author who worked on this research while at NASA's Goddard Space Flight Center, Greenbelt, Maryland.

Image Credit: Engine House VFX, At-Bristol Science Centre, University of Exeter
Explanation from: https://www.nasa.gov/feature/jpl/hubble-detects-exoplanet-with-glowing-water-atmosphere

Planetary Nebula NGC 6563

Planetary Nebula NGC 6563

The planetary nebula NGC 6563 resides in a crowded starry region of the sky. In natural sky conditions many of these stars remain invisible due to the blurring effect of the Earth’s atmosphere. When the AOF supplies its superb correction a myriad fainter stars become visible, together with a sharper view of the dusty parts of the nebula itself.

Image Credit: ESO/P. Weilbacher
Explanation from: https://www.eso.org/public/images/eso1724cb/

August 2, 2017

The Milky Way Galaxy

The Milky Way Galaxy

An arm of our Galaxy, the Milky Way Galaxy, crosses the photo from the mountains to the high heavens. The gas and dust of the Galaxy are brilliantly illuminated in this photograph.

Image Credit: S. Otarola/ESO

Planetary Nebula IC 4406

Planetary Nebula IC 4406

The coupling of the AOF with MUSE gives access to both greater sharpness and a wide dynamic range when observing celestial objects like planetary nebulae. These new observations of IC 4406 revealed shells that have never been seen before, along with the already familiar dark dust structures in the nebula that gave it the popular name the Retina Nebula.

This image shows a small fraction of the total data collected by the MUSE using the AOF system and demonstrates the increased abilities of the new AOF equipped MUSE instrument.

Image Credit: ESO/J. Richard
Explanation from: https://www.eso.org/public/images/eso1724a/

Sheet of Plasma

Sheet of Plasma

A sheet of plasma blasted out into space from just behind the edge of the Sun (July 28, 2017). While some material escaped into space, a portion of it was unable to break the pull of gravity and the magnetic forces nearby and can be seen falling back to the Sun. The 3.5 hours of action was captured in a wavelength of extreme ultraviolet light.

Image Credit: NASA/GSFC/Solar Dynamics Observatory
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21866

August 1, 2017

Jupiter's Great Red Spot

Jupiter's Great Red Spot

This image of Jupiter's iconic Great Red Spot (GRS) was created by citizen scientist Björn Jónsson using data from the JunoCam imager on NASA's Juno spacecraft.

This true-color image offers a natural color rendition of what the Great Red Spot and surrounding areas would look like to human eyes from Juno's position. The tumultuous atmospheric zones in and around the Great Red Spot are clearly visible.

The image was taken on July 10, 2017 at 07:10 p.m. PDT (10:10 p.m. EDT), as the Juno spacecraft performed its seventh close flyby of Jupiter. At the time the image was taken, the spacecraft was about 8,648 miles (13,917 kilometers) from the tops of the clouds of the planet at a latitude of -32.6 degrees.

Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Bjorn Jonsson
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21775

Planetary System Gliese 581

Planetary System Gliese 581

After more than four years of observations using the most successful low-mass exoplanet hunter in the world, the HARPS spectrograph attached to the 3.6-metre ESO telescope at La Silla, Chile, astronomers have discovered in this system the lightest exoplanet found so far: Gliese 581e (foreground) is only about twice the mass of our Earth. The Gliese 581 planetary system now has four known planets, with masses of about 1.9 (planet e, left in the foreground), 16 (planet b, nearest to the star), 5 (planet c, centre), and 7 Earth-masses (planet d, with the bluish colour). The planet furthest out, Gliese 581d, orbits its host star in 66.8 days, while Gliese 581 e completes its orbit in 3.15 days.

Image Credit: ESO/L. Calçada
Explanation from: https://exoplanets.nasa.gov/resources/174/

Galaxy Cluster PLCKESZ G286.6-31.3

Galaxy Cluster PLCKESZ G286.6-31.3

This image from the Wide-Field Imager on the MPG/ESO 2.2-metre telescope shows the starry skies around a galaxy cluster named PLCKESZ G286.6-31.3. The cluster itself is difficult to spot initially, but shows up as a subtle clustering of yellowish galaxies near the centre of the frame.

PLCKESZ G286.6-31.3 houses up to 1000 galaxies, in addition to large quantities of hot gas and dark matter. As such, the cluster has a total mass of 530 trillion (530 000 000 000 000) times the mass of the Sun.

When viewed from Earth, PLCKESZ G286.6-31.3 is seen through the outer fringes of the Large Magellanic Cloud (LMC) — one of the Milky Way’s satellite galaxies. The LMC hosts over 700 star clusters, in addition to hundreds of thousands of giant and supergiant stars. The majority of the cosmic objects captured in this image are stars and star clusters located inside the LMC .

The MPG/ESO 2.2-metre telescope has been in operation at ESO’s La Silla Observatory since 1984. The telescope has been utilised for a variety of cutting-edge scientific studies, including ground-breaking research into gamma-ray bursts, the most powerful explosions in the Universe. The 67-million-pixel Wide Field Imager (WFI) — mounted on the telescope’s Cassegrain focus — has been obtaining detailed views of faint, distant objects since 1999.

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/potw1731a/

July 31, 2017

Sunrise seen from the International Space Station

Sunrise seen from the International Space Station

On July 26, 2017, a member of the Expedition 52 crew aboard the International Space Station took this photograph of one of the 16 sunrises they experience every day, as the orbiting laboratory travels around Earth. One of the solar panels that provides power to the station is seen in the upper left.

The station's solar arrays produce more power than it needs at one time for station systems and experiments. When the station is in sunlight, about 60 percent of the electricity that the solar arrays generate is used to charge the station's batteries. The batteries power the station when it is not in the Sun.

Image Credit: NASA
Explanation from: https://www.nasa.gov/image-feature/sunrise-through-the-solar-arrays

Spiral Galaxy NGC 4656

Spiral Galaxy NGC 4656

This galaxy known as NGC 4656 is located in the constellation of Canes Venatici (The Hunting Dogs). However, it also has a somewhat more interesting and intriguing name: the Hockey Stick Galaxy! The reason for this is a little unclear from this partial view, which shows the bright central region, but the galaxy is actually shaped like an elongated, warped stick, stretching out through space until it curls around at one end to form a striking imitation of a celestial hockey stick.

This unusual shape is thought to be due to an interaction between NGC 4656 and a couple of near neighbours, NGC 4631 (otherwise known as The Whale Galaxy) and NGC 4627 (a small elliptical). Galactic interactions can completely reshape a celestial object, shifting and warping its constituent gas, stars, and dust into bizarre and beautiful configurations. The NASA/ESA Hubble Space Telescope has spied a large number of interacting galaxies over the years, from the cosmic rose of Arp 273 to the egg-penguin duo of Arp 142 and the pinwheel swirls of Arp 240.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1731a/

Saturn's Northern Hemisphere

Saturn's Northern Hemisphere

Saturn's northern hemisphere reached its summer solstice in mid-2017, bringing continuous sunshine to the planet's far north.

The solstice took place on May 24, 2017. The Cassini mission is using the unparalleled opportunity to observe changes that occur on the planet as the Saturnian seasons turn.

This view looks toward the sunlit side of the rings from about 17 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on April 17, 2017 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 939 nanometers.

The view was acquired at a distance of approximately 733,000 miles (1.2 million kilometers) from Saturn. Image scale is 44 miles (70 kilometers) per pixel.

Image Credit: NASA/JPL-Caltech/Space Science Institute
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21337