Friday, April 28, 2017

Cassini Captures Closest Images of Saturn's Atmosphere

This unprocessed image shows features in Saturn's atmosphere from closer than ever before. The view was captured by NASA's Cassini spacecraft during its first Grand Finale dive past the planet on April 26, 2017.

Credit: NASA/JPL-Caltech/Space Science Institute.


Lyrids in Southern Skies

Earth's annual Lyrid meteor shower peaked before dawn on April 22nd, as our fair planet plowed through dust from the tail of long-periodcomet Thatcher. Seen from the high, dark, and dry Atacama desert a waning crescent Moon and brilliant Venus join Lyrid meteor streaks in this composited view. Captured over 5 hours on the night of April 21/22, the meteors stream away from the shower's radiant, a point not very far on the sky from Vega, alpha star of the constellation Lyra. The radiant effect is due to perspective as the parallel meteor tracks appearto converge in the distance. In the foreground are domes of the Las Campanas Observatory housing (left to right) the 2.5 meter du Pont Telescope and the 1.3 meter Optical Gravitational Lensing Experiment (OGLE) telescope.
Image Credit & CopyrightYuri Beletsky(Carnegie Las Campanas ObservatoryTWAN)

Wednesday, April 26, 2017

Between the Rings of Saturn

On April 12, as the Sun was blocked by the disk of Saturn the Cassini spacecraft camera looked toward the inner Solar System and the gas giant's backlit rings. At the top of the mosaicked view is the A ring with its broader Encke and narrower Keeler gaps visible. At the bottom is the F ring, bright due to the viewing geometry. The point of light between the rings is Earth, 1.4 billion kilometers in the distance. Look carefullyand you can even spot Earth's large moon, a pinprick of light to the planet's left. Today Cassini makes its final close approach to Saturn's own large moon Titan, using Titan's gravity to swing into the spacecraft's Grand Finale, the final set of orbits that will bring Cassini just inside Saturn's rings.
Image Credit: Cassini Imaging TeamSSIJPL,ESANASA


Hubble's Cosmic Bubble

This entrancing image shows a few of the tenuous threads that comprise Sh2-308, a faint and wispy shell of gas located 5,200 light-years away in the constellation of Canis Major (The Great Dog).

Sh2-308 is a large bubble-like structure wrapped around an extremely large, bright type of star known as a Wolf-Rayet Star '” this particular star is called EZ Canis Majoris. These type of stars are among the brightest and most massive stars in the Universe, tens of times more massive than our own sun, and they represent the extremes of stellar evolution. Thick winds continually poured off the progenitors of such stars, flooding their surroundings and draining the outer layers of the Wolf-Rayet stars. The fast wind of a Wolf-Rayet star therefore sweeps up the surrounding material to form bubbles of gas.

EZ Canis Majoris is responsible for creating the bubble of Sh2-308 '” the star threw off its outer layers to create the strands visible here. The intense and ongoing radiation from the star pushes the bubble out farther and farther, blowing it bigger and bigger. Currently the edges of Sh2-308 are some 60 light-years apart!

Beautiful as these cosmic bubbles are, they are fleeting. The same stars that form them will also cause their death, eclipsing and subsuming them in violent supernova explosions.

Credit: ESA/Hubble andamp; NASA
Text credit: European Space Agency

Hubble Space Telescope

Saturday, April 22, 2017

NGC 4302 and NGC 4298

Seen edge-on, spiral galaxy NGC 4302 (left) lies about 55 million light-years away in the well-groomed constellation Coma Berenices. A member of the large Virgo Galaxy Cluster, it spans some 87,000 light-years, a little smaller than our own Milky Way. Like the Milky Way, NGC 4302's prominent dust lanes cut along the center of the galactic plane, obscuring and reddening the starlight from our perspective. Smaller companion galaxy NGC 4298 is also a dusty spiral. But tilted more nearly face-on to our view, NGC 4298 can show off dust lanes along spiral arms traced by the bluish light of young stars, as well as its bright yellowish core. In celebration of the 27th anniversary of the launch of the Hubble Space Telescope on April 24, 1990, astronomers used the legendary telescope to take this gorgeous visible light portrait of the contrasting galaxy pair.
Image Credit: NASAESA, M. Mutchler (STScI)

Wednesday, April 19, 2017

The Red Spider Planetary Nebula

Oh what a tangled web a planetary nebula can weave. The Red Spider Planetary Nebula shows the complex structure that can result when anormal star ejects its outer gases and becomes a white dwarf star. Officially tagged NGC 6537, this two-lobed symmetric planetary nebulahouses one of the hottest white dwarfs ever observed, probably as part of a binary starsystem. Internal winds emanating from the central stars, visible in the center, have been measured in excess of 1000 kilometers per second. These winds expand the nebula, flow along the nebula's walls, and cause waves of hot gas and dust to collide. Atoms caught in these colliding shocks radiate light shown in the above representative-color picture by theHubble Space Telescope. The Red Spider Nebula lies toward the constellation of the Archer (Sagittarius). Its distance is not well known but has been estimated by some to be about 4,000 light-years.
Image Credit: NASAESAHubbleHLA;Reprocessing & Copyright: Jesús M.Vargas & Maritxu Poyal

Hubble Space Telescope

Tuesday, April 18, 2017

Watercolor World

When imaged at infrared wavelengths that pierce the planet’s upper haze layer, the high-speed winds of Saturn's atmosphere produce watercolor-like patterns.

With no solid surface creating atmospheric drag, winds on Saturn can reach speeds of more than 1,100 miles per hour (1,800 kilometers per hour) -- some of the fastest in the solar system.

This view was taken from a vantage point about 28 degrees above Saturn's equator. The image was taken with the Cassini spacecraft wide-angle camera on Dec. 2, 2016, with a combination of spectral filters which preferentially admits wavelengths of near-infrared light centered at 728 nanometers.

The view was acquired at a distance of approximately 592,000 miles (953,000 kilometers) from Saturn. Image scale is 35 miles (57 kilometers) per pixel.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

Credit: NASA/JPL-Caltech/Space Science Institute


Hubble sees Starbursts in Virgo

Although galaxy formation and evolution are still far from being fully understood, the conditions we see within certain galaxies -- such as so-called starburst galaxies  -- can tell us a lot about how they have evolved over time. Starburst galaxies contain a region (or many regions) where stars are forming at such a breakneck rate that the galaxy is eating up its gas supply faster than it can be replenished!

NGC 4536 is such a galaxy, captured here in beautiful detail by the Hubble?s Wide Field Camera 3 (WFC3). Located roughly 50 million light-years away in the constellation of Virgo (The Virgin), it is a hub of extreme star formation. There are several different factors that can lead to such an ideal environment in which stars can form at such a rapid rate. Crucially, there has to be a sufficiently massive supply of gas. This might be acquired in a number of ways -- for example by passing very close to another galaxy, in a full-blown galactic collision, or as a result of some event that forces lots of gas into a relatively small space.

Star formation leaves a few tell-tale fingerprints, so astronomers can tell where stars have been born. We know that starburst regions are rich in gas. Young stars in these extreme environments often live fast and die young, burning extremely hot and exhausting their gas supplies fairly quickly. These stars also emit huge amounts of intense ultraviolet light, which blasts the electrons off any atoms of hydrogen lurking nearby (a process called ionization), leaving behind often colorful clouds of ionized hydrogen (known in astronomer-speak as HII regions).

Credit: ESA/Hubble & NASA
Text Credit: European Space Agency

Hubble Space Telescope

Illustration of Cassini Space craft Diving through Plum of 'Ocean world' Enceladus

This illustration shows NASA's Cassini spacecraft diving through the plume of Saturn's moon Enceladus, in 2015. Two veteran NASA missions are providing new details about icy, ocean-bearing moons of Jupiter and Saturn, further heightening the scientific interest of these and other "ocean worlds" in our solar system and beyond.

Sunday, April 16, 2017

Leo Trio Galaxies

This group is popular in the northern spring. Famous as the Leo Triplet, the three magnificent galaxies gather in one field of view. Crowd pleasers when imaged with even modest telescopes, they can be introduced individually as NGC 3628 (left), M66 (bottom right), and M65 (top). All three are large spiral galaxies but they tend to look dissimilar because their galactic disks are tilted at different angles to our line of sight. NGC 3628 is seen edge-on, with obscuring dust lanes cutting across the plane of the galaxy, while the disks of M66 andM65 are both inclined enough to show off their spiral structure. Gravitational interactions between galaxies in the group have also left telltale signs, including the warped and inflated disk of NGC 3628 and the drawn out spiral arms of M66. This gorgeous view of the region spans about one degree (two full moons) on the sky. The field covers over 500 thousand light-years at the trio's estimated distance of 30 million light-years.
Image Credit & CopyrightIgnacio Diaz Bobillo

Saturday, April 15, 2017

Man, Sun and Dog

This was supposed to be a shot of trees in front of a setting Sun. Sometimes, though, the unexpected can be photogenic. During some planning shots, a man walking his dogunexpected crossed the ridge. The result was so striking that, after cropping, it became the main shot. The reason the Sun appears so largeis that the image was taken from about a kilometer away through a telephoto lens. Scattering of blue light by the Earth's atmosphere makes the bottom of the Sun appear slightly more red that the top. Also, if you look closely at the Sun, just above the man's head, a large group of sunspots is visible. The image was taken just last week in BadMergentheimGermany.
Image Credit & Copyright: Jens Hackmann

Tuesday, April 11, 2017

Castle Eye View

The best known asterism in northern skies, The Big Dipper is easy to recognize, even when viewed upside down, though some might see aplough or wagon. The star names and the familiar outlines appear framed in the ruined tower walls of the French Chateau du Morimontif you just slide your cursor over the image or follow this linkDubhe, alpha star of the dipper's parent constellation Ursa Major is at the lower left. Together with beta star Merak the two forma line pointing the way to Polaris and the North Celestial Pole, hidden from view by the stones. Since the image was captured on March 30, you can follow a line from dipper stars Phecda and Megrez to spot the faint greenish glow ofComet 41P/Tuttle-Giacobini-Kresak below center, still within the castle eye view. The periodic comet made a remarkable closeapproach to planet Earth on April 1.
Image Credit & Copyright: Stephane Vetter (Nuits sacrees, TWAN)

Dark Nebula LDN 1622 and Barnard's Loop

The silhouette of an intriguing dark nebulainhabits this cosmic scene. Lynds' Dark Nebula (LDN) 1622 appears below center against a faint background of glowing hydrogen gas only easily seen in long telescopic exposures of the region. LDN 1622 lies near the plane of our Milky Way Galaxy, close on the sky to Barnard's Loop - a large cloud surrounding the richcomplex of emission nebulae found in the Belt and Sword of Orion. Arcs along a segment of Barnard's loop stretch across the top of the frame. But the obscuring dust of LDN 1622 is thought to be much closer than Orion's more famous nebulae, perhaps only 500 light-years away. At that distance, this 1 degree wide field of view would span less than 10 light-years.
Credit & Copyright: Leonardo Julio (Astronomia Pampeana)

Monday, April 10, 2017

Expedition 50 Soyuz MS 02 Landing

The Soyuz MS-02 spacecraft is seen as it lands with Expedition 50 Commander Shane Kimbrough of NASA and Flight Engineers Sergey Ryzhikov and Andrey Borisenko of Roscosmos near the town of Zhezkazgan, Kazakhstan on Monday, April 10, 2017 (Kazakh time).

Tuesday, April 4, 2017

Saturn in Infrared from Cassini

Many details of Saturn appear clearly in infrared light. Bands of clouds show great structure, including long stretching storms. Also quite striking in infrared is the unusual hexagonal cloud pattern surrounding Saturn's North Pole. Each side of the dark hexagon spans roughly the width of our Earth. The hexagon's existence was not predicted, and its origin and likely stability remains a topic of research. Saturn's famous rings circle the planet and cast shadows below the equator. The featured image was taken by the robotic Cassini spacecraft in 2014 in severalinfrared colors -- but only processed recently. In September, Cassini's mission will be brought to a dramatic conclusion as the spacecraft will be directed to dive into ringed giant.
Image Credit: NASAJPL-CaltechSSIProcessing: Maksim Kakitsev


Hubble spots two interacting Galaxies defying cosmic Convention

Some galaxies are harder to classify than others. Here, Hubble’s trusty Wide Field Camera 3 (WFC3) has captured a striking view of two interacting galaxies located some 60 million light-years away in the constellation of Leo (The Lion). The more diffuse and patchy blue glow covering the right side of the frame is known as NGC 3447 — sometimes NGC 3447B for clarity, as the name NGC 3447 can apply to the overall duo. The smaller clump to the upper left is known as NGC 3447A.
Overall, we know NGC 3447 comprises a couple of interacting galaxies, but we’re unsure what each looked like before they began to tear one another apart. The two sit so close that they are strongly influenced and distorted by the gravitational forces between them, causing the galaxies to twist themselves into the unusual and unique shapes seen here. NGC 3447A appears to display the remnants of a central bar structure and some disrupted spiral arms, both properties characteristic of certain spiral galaxies. Some identify NGC 3447B as a former spiral galaxy, while others categorize it as being an irregular galaxy.
Image credit: ESA/Hubble & NASA
Text credit: European Space Agency

Saturday, April 1, 2017

Hubble's Double Galaxy Gaze: Leda and NGC 4424

Some astronomical objects have endearing or quirky nicknames, inspired by mythology or their own appearance. Take, for example, the constellation of Orion (The Hunter), the Sombrero Galaxy, the Horsehead Nebula, or even the Milky Way. However, the vast majority of cosmic objects appear in astronomical catalogs and are given rather less poetic names based on the order of their discovery.

Two galaxies are clearly visible in this Hubble image, the larger of which is NGC 4424. This galaxy is cataloged in the New General Catalog of Nebulae and Clusters of Stars (NGC), which was compiled in 1888. The NGC is one of the largest astronomical catalogs, which is why so many Hubble Pictures of the Week feature NGC objects. In total there are 7,840 entries in the catalog and they are also generally the larger, brighter, and more eye-catching objects in the night sky, and hence the ones more easily spotted by early stargazers.

The smaller, flatter, bright galaxy sitting just below NGC 4424 is named LEDA 213994. The Lyon-Meudon Extragalactic Database (LEDA) is far more modern than the NGC and contains millions of objects.

Many NGC objects still go by their initial names simply because they were christened within the NGC first. However, since astronomers can't resist a good acronym and 'Leda'� is more appealing than 'the LMED,'� the smaller galaxy is called "Leda." Leda was a princess in Ancient Greek mythology.

Text credit: European Space Agency
Image credit: ESA/Hubble andamp; NASA

Hubble Space Telescope

The Comet, the Owl and the Galaxy

Comet 41P/Tuttle-Giacobini-Kresak poses for a Messier moment in this telescopic snapshot from March 21. In fact it shares the 1 degree wide field-of-view with two well-known entries in the 18th century comet-hunting astronomer'sfamous catalog. Sweeping through northernspringtime skies just below the Big Dipper, the faint greenish comet was about 75 light-seconds from our fair planet. Dusty, edge-on spiral galaxy Messier 108 (bottom center) is more like 45 million light-years away. At upper right, the planetary nebula with an aging but intensely hot central star, the owlish Messier 97is only about 12 thousand light-years distant though, still well within our own Milky Way galaxy. Named for its discoverer and re-discoverers, this faint periodic comet was first sighted in 1858 and not again until 1907 and 1951. Matching orbit calculations indicated that the same comet had been observed at widely separated times. Nearing its best apparition and closest approach to Earth in over 100 years on April 1, comet 41P orbits the Sun with a period of about 5.4 years.
Image Credit & CopyrightBarry Riu