Kraken Mare

The Cassini spacecraft looks toward Saturn's largest moon, Titan, and spies the huge Kraken Mare in the moon's north.

Kraken Mare, a large sea of liquid hydrocarbons, is visible as a dark area near the top of the image. See PIA12811 and PIA11626 to learn more.

This view looks toward the Saturn-facing side of Titan (3,200 miles across, or 5,150 kilometers,). North on Titan is up and rotated 29 degrees to the left.

The image was taken with the Cassini spacecraft narrow-angle camera on September 14, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers. The view was acquired at a distance of approximately 1.2 million miles (1.9 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 26 degrees. Image scale is 7 miles (12 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Eta Carinae

This new image of the luminous blue variable Eta Carinae was taken with the NACO near-infrared adaptive optics instrument on ESO's Very Large Telescope, yielding an incredible amount of detail. The images clearly shows a bipolar structure as well as the jets coming out from the central star. The image was obtained by the Paranal Science team and processed by Yuri Beletsky (ESO) and Hännes Heyer (ESO). It is based on data obtained through broad (J, H, and K; 90 second exposure time per filters) and narrow-bands (1.64, 2.12, and 2.17 microns; probing iron, molecular and atomic hydrogen, respectively; 4 min per filter).

Photo credit: ESO

The Center of the Milky Way

The central parts of our Galaxy, the Milky Way, as observed in the near-infrared with the NACO instrument on ESO's Very Large Telescope. By following the motions of the most central stars over more than 16 years, astronomers were able to determine the mass of the supermassive black hole that lurks there.

Photo credit: ESO/S. Gillessen et al.

Launch of the Mars Science Laboratory ("Curiosity")

The Minister needs to get to bed, but he first wants to add two videos of the Mars Rover Curiosity launching successfully from Cape Canaveral today. Captions for the videos will come later. This first video is from NASAtelevision:



This second video is a much longer version:

Eberswalde Crater

Eberswalde crater on Mars formed more than 3.7 billion years ago. The rim of the crater is intact only in the north-eastern part. The rest has been buried by ejecta from the larger, more recent Holden impact crater nearby. The image was acquired by Mars Express around 25°S/326°E during orbit 7208 on 15 August 2009. The images have a ground resolution of about 22m per pixel.

Photo credit: ESA/DLR/FU Berlin (G. Neukum)

NGC 2264 - The Cone Nebula and the Christmas Tree Star Cluster

This color image of the region known as NGC 2264 — an area of sky that includes the sparkling blue baubles of the Christmas Tree star cluster and the Cone Nebula — was created from data taken through four different filters (B, V, R and H-alpha) with the Wide Field Imager at ESO's La Silla Observatory, 2400 m high in the Atacama Desert of Chile in the foothills of the Andes. The image shows a region of space about 30 light-years across.

Photo credit: ESO

Cygnus X-1

Over three decades ago, Stephen Hawking placed, and eventually lost, a bet against the existence of a black hole in Cygnus X-1. Today, astronomers are confident the Cygnus X-1 system contains a black hole. In fact, a team of scientists has combined data from radio, optical, and X-ray telescopes including Chandra to determine the black hole's spin, mass, and distance more precisely than ever before. With these key pieces of information, the history of the black hole has been reconstructed. This new information gives astronomers strong clues about how the black hole was born, how much it weighed, and how fast it was spinning. This is important because scientists still would like to know much more about the birth of black holes.

Video credit: Optical: DSS; Illustration: NASA/CXC/M.Weiss

Note: For more information, see Cygnus X-1: NASA's Chandra Adds to Black Hole Birth Announcement.

Topography of Mars

Color coding in this image of Mars represents differences in elevation, measured by the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. While surface liquid water is rare and ephemeral on modern Mars, the topography of Mars reveals large, ancient valley networks and outflow channels. These are evidence that liquid water was more common and played a much more important role in Mars' past.

Image credit: NASA/JPL-Caltech

Note: The view of this map is somewhat unusual; we are looking from the north to the south. The "blue land" to the left is Acidalia Planitia (dark blue) and Chryse Planitia (light blue). The "green land" on the far left limb is Arabia Terra, while the green and yellow land to the middle right is Lunae Planum (lower right) and Xanthe Terra (upper middle right, with the large craters). The long blue and green streak in the "red land" is Valles Marineris; that leads to the various chasmata and chaotic terrains that lie near the top (southernmost) limb of the planet. The green "dogleg" at the bottom right is Echus Chasma (far right) and Kasei Valles (middle right), which flowed into Chryse Planitia.

Hypothesized Formation of the First Stars

Scientists are simulating how the very first stars in our universe were born. This diagram shows a still from one such simulation. The cube on the right is a blown up region at the center of the box on the left.

The stars we see today formed out of collapsing clouds of gas and dust. In the very early universe, however, the stars had fewer ingredients available. There wasn't any dust yet, or heavy elements, both of which help cool the gas in a cloud so that it can collapse. Instead, the very first stars formed from nothing but hydrogen and helium gas. Astronomers theorize that, in order to overcome their lack of cooling ingredients, these stars would have needed more mass to form. The first stars were thought to have been more massive than even the most massive stars observed today.

At the very center of each box shown here is the forming star - the star itself is too small to see at this scale. The red areas show hot gas with temperatures as high as 50,000 Kelvin (90,000 degrees Fahrenheit), heated by, and surrounding, the forming star. Blue shows much cooler gas, with the darkest blue showing the densest portions of cool gas, shaped like a disk surrounding the seedling star.

As the star pulls matter from the disk onto it, it grows more massive. Meanwhile, some gas -- shown in the red areas -- is so hot that it expands and escapes. Eventually, large amounts of the surrounding gas become too hot and escape. At this point, the star stops growing -- it has finished "baking."

Scientists at NASA's Jet Propulsion Laboratory, Pasadena, California, have used these simulations to show that the first stars, during their formation, had a greater impact on surrounding gas than previously thought. The higher gas temperatures would have caused the stars to stop growing sooner. As a result, the first stars were not likely hundreds of times the mass of the Sun, but only tens of times its mass.

None of these first stars still exist today. After a few million years they exploded in fiery supernovae, spewing heavier elements cooked in their interiors out into the surrounding gas.

For technical details and videos visit http://www-tap.scphys.kyoto-u.ac.jp/~hosokawa/firststarstop_e.html.

Photo credit: NASA/JPL-Caltech/Kyoto University

The Carina Nebula

Observations made with the APEX telescope in sub-millimeter-wavelength light at a wavelength of 870 µm reveal the cold dusty clouds from which stars form in the Carina Nebula. This site of violent star formation, which plays host to some of the highest-mass stars in our galaxy, is an ideal arena in which to study the interactions between these young stars and their parent molecular clouds.

The APEX observations, made with its LABOCA camera, are shown here in orange tones, combined with a visible light image from the Curtis Schmidt telescope at the Cerro Tololo Interamerican Observatory. The result is a dramatic, wide-field picture that provides a spectacular view of Carina’s star formation sites. The nebula contains stars equivalent to over 25,000 Suns, and the total mass of gas and dust clouds is that of about 140,000 Suns.

Photo credit: ESO/APEX/T. Preibisch et al. (Submillimetre); N. Smith, University of Minnesota/NOAO/AURA/NSF (Optical)

Note: For more information, see The Cool Clouds of Carina. See also Tarantula Nebula (30 Doradus): 30 Doradus and The Growing Tarantula Within .

Vesta's Domitia Crater

These Dawn FC (framing camera) images show the Domitia crater in Vesta's northern hemisphere and the topography of the surrounding region, which includes the "Snowman" craters. Domitia crater is the roughly 50km diameter crater in the top of the image, slightly offset from the center of the image. It is a highly degraded crater and its rim is nearly totally obscured by smaller, younger impact craters. Domitia crater is both large and distinctive so its name is used to name the quadrangle in which it is located. The left image is an albedo image, which is taken directly through the clear filter of the FC. Such an image shows the albedo (e.g. brightness/darkness) of the surface. The right image uses the same albedo image as its base but then a color-coded height representation of the topography is overlain onto it. The topography is calculated from a set of images that were observed from different viewing directions, called stereo images. The various colors correspond to the height of the area that they color. For example, the white area in the bottom right of the image is the highest area and the dark blue top edge of the image is the lowest area. The bottom edge of Domitia crater is located on the boundary between the dark and light blue so it defines a sharp topography/height boundary.

This image is in Vesta's Domitia, Marcia and Numisia quadrangles and the center latitude and longitude of the image is 22.3°N, 198.7°E. NASA's Dawn spacecraft obtained this image with its framing camera on August 29th 2011. This image was taken through the camera's clear filter. The distance to the surface of Vesta is 2740 km and the image has a resolution of about 250 meters per pixel. This image was acquired during the Survey phase of the mission.

Photo credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

30 Doradus in Infrared and X-Rays

The star-forming region, 30 Doradus, is one of the largest located close to the Milky Way and is found in the neighboring galaxy Large Magellanic Cloud. About 2,400 massive stars in the center of 30 Doradus, also known as the Tarantula Nebula, are producing intense radiation and powerful winds as they blow off material.

Multi-million-degree gas detected in X-rays (blue) by the Chandra X-ray Observatory comes from shock fronts -- similar to sonic booms -- formed by these stellar winds and by supernova explosions. This hot gas carves out gigantic bubbles in the surrounding cooler gas and dust shown here in infrared emission from the Spitzer Space Telescope (orange).

30 Doradus is also known as an HII (pronounced "H-two") region, created when the radiation from hot, young stars strips away the electrons from neutral hydrogen atoms (HI) to form clouds of ionized hydrogen (HII). It is the most massive and largest HII region in the Local Group of galaxies, which contains the Milky Way, Andromeda and about 30 other smaller galaxies including the two Magellanic Clouds. Because of its proximity and size, 30 Doradus is an excellent target for studying the effects of massive stars on the evolution of an HII region.

The Tarantula Nebula is expanding, and researchers have recently published two studies that attempt to determine what drives this growth. The most recent study concluded that the evolution and the large-scale structure of 30 Doradus is determined by the bubbles of hot, X-ray bright gas confined by surrounding gas, and that pressure from radiation generated by massive stars does not currently play an important role in shaping the overall structure. A study published earlier in 2011 came to the opposite conclusion and argued that radiation pressure is more important than pressure from hot gas in driving the evolution of 30 Doradus, especially in the central regions near the massive stars. More detailed analysis and deeper Chandra observations of 30 Doradus may help decide between these different ideas.

Photo credit: X-ray: NASA/CXC/PSU/L. Townsley et al.; Infrared: NASA/JPL/PSU/L. Townsley et al.

Saturn's Northern Hemisphere Storm

Saturn's northern storm marches through the planet's atmosphere in the top right of this false-color mosaic from NASA's Cassini spacecraft.

See PIA14905 to learn more about this storm and watch its development over several months. Earlier in the Cassini mission, the spacecraft chronicled a smaller storm in the southern hemisphere, called the "Dragon Storm." See PIA06197 to learn more about that storm and to see a similar, false-color view.

Saturn's atmosphere and its rings are shown here in a false-color composite made from 12 images taken in near-infrared light through filters that are sensitive to varying degrees of methane absorption. Red and orange colors in this view indicate clouds that are deep in the atmosphere. Yellow and green colors, most noticeable along the top edge of the view, indicate intermediate clouds. White and blue indicate high clouds and haze. The rings appear as a thin horizontal line of bright blue because they are outside of the atmosphere and not affected by methane absorption.

This view looks toward the northern, sunlit side of the rings from just above the ring plane.

The images were taken with the Cassini spacecraft wide-angle camera using a combination of spectral filters sensitive to wavelengths of near-infrared light. The images filtered at 890 nanometers are projected as blue. The images filtered at 728 nanometers are projected as green, and images filtered at 752 nanometers are projected as red.

The images were taken on January 11, 2011, over about 50 minutes, at a distance of approximately 569,000 miles (915,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 45 degrees. The images were re-projected to the same viewing geometry, so that scale in this final mosaic is 63 miles (102 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Note: For other photos in this series, see PIA12828: Storm Head in False Color, PIA12829: Storm Tail in False Color, PIA14901: Eleven Hours Later, PIA14902: Birth of a Behemoth Storm, PIA14903: Encircling a Giant, PIA14904: Nearly True Color Storm Close-Up, PIA14905: Chronicling Saturn's Northern Storm, PIA14906: Churning Psychedelia, and PIA14907: Kaleidoscopic Rainbows.

Astrophysical Shock Waves

This composition shows a number of diverse astronomical sources where shocks have been detected. Shock waves arise when supersonic flows of plasma are faced with an obstacle, such as a planet or a star with a magnetic field, or when they encounter a slower moving flow.

Depicted in the composition are: a bow shock around the very young star, LL Ori, in the Great Orion Nebula (upper row, left image); shock waves around the Red Spider Nebula, a warm planetary nebula (upper row, central image); very thin shocks on the edge of the expanding supernova remnant SN 1006 (central row, left image); artist's impressions of the bow shock created by the Solar System as it moves through the interstellar medium of the Milky Way (upper row, right image) and of Earth's bow shock, formed by the solar wind as it encounters our planet's magnetic field (central row, right image); shock-heated shells of hot gas on the edge of the lobes of the radio galaxy Cygnus A (lower row, left image); a bow shock in the hot gas in the merging galaxy cluster 1E 0657-56, also known as the 'Bullet Cluster'.

The image of a galaxy (NGC 6744) in the center of the composition serves to give a rough idea of the relative scales, sub- and super-galactic alike, of the shock waves present across the Universe.

Illustration credit: NASA/ESA and The Hubble Heritage Team STScI/AURA (LL Ori); ESA & Garrelt Mellema, Leiden University, the Netherlands (Red Spider Nebula); CEA/DSM/DAPNIA/SAp and ESA/XMM-Newton (SN 1006); ESA & Lotfi Ben Jaffel, Institut d'Astrophysique de Paris-CNRS-INSU, Martin Kornmesser & Lars Lindberg Christensen (Solar System); ESA/AOES Medialab (Earth's bow shock); ESO (NGC 6744); NRAO/AUI (Cygnus A); NASA/CXC/CfA/M.Markevitch et al. (Bullet Cluster).

Bachu and the Tian Shan Mountains

Varied elevations of Bachu in western China in an image developed using data from the two ERS satellites. The ERS missions pioneered the technique of processing satellite radar data into digital elevation models, as shown here of Bachu and the nearby Tian Shan mountains. A digital elevation model is a 3D relief map to study changes in the terrain.

Photo credit: ESA/DLR

Update: Another ESA photo of the Tian Shan mountains can be found here.

Time-Lapse Views of the Earth

Another great video compilation of the Earth from the International Space Station. The photos were taken by Ron Garan, Satoshi Furukawa and the crew of Expeditions 28 & 29 from August to October, 2011. Below is a list of the different sequences and the ground they cover:

1. Aurora Borealis pass over the United States at night
2. Aurora Borealis and eastern United States at night
3. Aurora Australis from Madagascar to southwest of Australia
4. Aurora Australis south of Australia
5. Northwest coast of United States to central South America at night
6. Aurora Australis from the southern to the northern Pacific Ocean
7. Halfway around the World
8. Night pass over central Africa and the Middle East
9. Evening pass over the Sahara Desert and the Middle East
10. Pass over Canada and central United States at night
11. Pass over Southern California to Hudson Bay
12. Islands in the Philippine Sea at night
13. Pass over eastern Asia to Philippine Sea and Guam
14. Views of the Middle East at night
15. Night pass over Mediterranean Sea
16. Aurora Borealis and the United States at night
17. Aurora Australis over Indian Ocean
18. Eastern Europe to Southeast Asia at night

Images credit: NASA; Editing: Michael König; Music: Jan Jelinek | Do Dekor, faitiche back

Tiny Galaxies Brimming with Star Birth

This image reveals 18 tiny galaxies uncovered by the NASA/ESA Hubble Space Telescope. The puny galaxies, shown in the postage-stamp-sized images, existed 9 billion years ago and are brimming with star birth.

The dwarf galaxies are typically a hundred times less massive than the Milky Way galaxy but are churning out stars at such a furious pace that their stellar population would double in just 10 million years. Hubble's Wide Field Camera 3 and Advanced Camera for Surveys spied the galaxies in a field called the Great Observatories Origins Deep Survey (GOODS). The galaxies' locations in the GOODS field are marked in the large image.

The galaxies stood out in the Hubble images because the energy from all the new stars caused the oxygen in the gas surrounding them to light up like a bright fluorescent sign. The rapid star birth likely represents an important phase in the formation of dwarf galaxies, the most common galaxy type in the cosmos.

The galaxies are among 69 dwarf galaxies found in the GOODS and other fields.

Images of the individual galaxies were taken November 2010 to January 2011. The large image showing the location of the galaxies was taken between September 2002 and December 2004, and between September 2009 and October 2009.

Photo credit: NASA, ESA, A. van der Wel (Max Planck Institute for Astronomy), H. Ferguson and A. Koekemoer (Space Telescope Science Institute), and the CANDELS team

Note: For more information, see Hubble Uncovers Tiny Galaxies Bursting with Starbirth in Early Universe; also, see Hubble Spies Tiny Galaxies Aglow with Star Birth.

Development of the Inner Solar System

This artist’s impression shows four stages of the development of the inner Solar System over a period of nearly five billion years. The top panel shows the earliest stage where the debris disc around the Sun was composed of gas and tiny particles, typically less than one millimeter across. At the second stage the particles have formed large clumps, roughly 100 kilometers across and, similar to the asteroid Lutetia. These bodies in turn formed the rocky planets including the Earth, shown in the third panel down. Over the subsequent four billion years the surface of the Earth developed to what we know now under the influence of meteor bombardment that delivered volatile materials including water, and the evolution of life on its surface.

The rare spectral properties show that Lutetia started life as a fragment of the material that was forming the inner planets but was ejected. It is now found as an unusual interloper in the main belt of asteroids, much further from the Sun.

Illustration credit: ESO/L. Calçada and N. Risinger

Note: For more information, see Lutetia: a Rare Survivor from the Birth of the Earth.

Tharsis Tholus

Tharsis Tholis towers 8 km above the surrounding terrain with a base that stretches 155 x 125 km and a central caldera measuring 32 x 34 km. The image was created using a Digital Terrain Model (DTM) obtained from the High Resolution Stereo Camera on ESA’s Mars Express spacecraft. Elevation data from the DTM is color-coded: purple indicates the lowest lying regions and beige the highest. The scale is in meters. In these images, the relief has been exaggerated by a factor of three.

Photo credit: ESA/DLR/FU Berlin (G. Neukum)

Note: For more information (and a lot of other, great images), see Battered Tharsis Tholus Volcano on Mars.

Mars Science Laboratory atop the Atlas V

In the Vertical Integration Facility at Space Launch Complex 41, the payload fairing containing NASA's Mars Science Laboratory spacecraft was attached to its Atlas V rocket on November 3, 2011.

The spacecraft was prepared for launch in the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center. Its components include a car-sized rover, Curiosity, which has 10 science instruments designed to search for evidence about whether Mars has had environments favorable to microbial life, including the chemical ingredients for life.

Launch of the Mars Science Laboratory aboard a United Launch Alliance Atlas V rocket is planned for November 25 from Space Launch Complex 41 on Cape Canaveral Air Force Station.

Photo credit: NASA

Note: For other pictures showing Curiosity being prepared for launch, see:
* PIA15020: Mars Science Laboratory Descent Stage
* PIA15021: Mars Science Laboratory Rover Closeout
* PIA15022: Mars Science Laboratory Powered Descent Vehicle
* PIA15023: Integrating Powered Descent Vehicle with Back Shell of Mars Spacecraft
* PIA15026: Mars Science Laboratory Cruise Stage
* PIA15027: Mars Science Laboratory Heat Shield Integration for Flight
* PIA15028: Mars Science Laboratory Stacked Spacecraft
* PIA15029: Mars Science Laboratory and Its Payload Fairing
* PIA15030: Hoisting NASA's Mars Science Laboratory Onto Its Atlas V

IC 4601 - Dusty Reflections in the Scorpion's Claws

Between the claws of the dreaded scorpion imagined by the ancient Greeks lies this giant dust cloud, imaged by the Wide-field Infrared Survey Explorer, or WISE. The constellation of Scorpius is prominent in the summer night sky in North America. In visible light, this cloud, or nebula, appears dark with a ghostly blue shine about it. These types of nebulae are called "reflection," because they are reflecting the light of nearby stars. The dust within the cloud reflects mostly blue light.

However, WISE sees infrared light invisible to the eye. In infrared light, we can see the dust itself glowing rather than simply reflecting light. The green and red colors in this image show dust at different temperatures, with the green dust being warmer than the red dust. The dust is warmed by the light of nearby stars. This interstellar dust contains the heavy elements that planets are made of, and plays a major role in the creation of new stars.

The nebula, known as IC 4601, is part of a larger complex of clouds where new stars are being born. Some of the red stars in this image may in fact be baby stars wrapped in blankets of dust. Perhaps the dreaded scorpion can be thought of as rocking the baby stars to sleep.

This image was made from observations by all four infrared detectors aboard WISE. Blue and cyan (blue-green) represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily from stars, the hottest objects pictured. Green and red represent light at 12 and 22 microns, which is primarily from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

NGC 4522 Stripped

This image from NASA's Galaxy Evolution Explorer shows galaxy NGC 4522 being stripped of its star-forming material. Astronomers refer to this process as "ram-pressure stripping" - where surrounding hot-gas shoves star-forming gas out of the galaxy's outer disk. NGC 4522 is located approximately 50 million light-years away in the Virgo galaxy cluster.

In this image, the galaxy's older stellar population is marked by tints of yellow. Meanwhile, the bluish-white ridge near NGC 4522's center reveals a population of very young stars - most likely less than a million years old. The bluish-white coloration also indicates that new stars are actively forming in this area.

The light-blue haze beyond the white-ridge represents the galaxy's outer disk. This area is currently not a site of active star formation, but is still very bright in the ultraviolet, indicating that some stars in this region are very young and likely formed very recently, within the last 50-100 million years.

This image is a three color composite where yellow represents R-band visible-light data from the Kitt Peak National Observatory's 0.9-meter telescope. Green shows near-ultraviolet light data, and blue reveals far-ultraviolet light data from GALEX.

Photo credit: NASA/JPL-Caltech/Yale University/H. Crowl (Yale University)

Note: This image was used as an example in a recent Science@NASA article entitled Stellar Extremophiles.

Asteroid 2005 YU55

This radar image of asteroid 2005 YU55 was obtained NASA's Deep Space Network antenna in Goldstone, California on November 7, 2011, at 11:45 a.m. PST (2:45 p.m. EST/1945 UTC), when the space rock was at 3.6 lunar distances, which is about 860,000 miles, or 1.38 million kilometers, from Earth.

The asteroid safely will safely fly past our planet slightly closer than the moon's orbit on November 8. The last time a space rock this large came as close to Earth was in 1976, although astronomers did not know about the flyby at the time. The next known approach of an asteroid this size will be in 2028.

The image was taken on November 7 at 11:45 a.m. PST (2:45 p.m. EST/1945 UTC), when the asteroid was approximately 860,000 miles (1.38 million kilometers) away from Earth. Tracking of the aircraft carrier-sized asteroid began at Goldstone at 9:30 a.m. PDT on November 4 with the 230-foot-wide (70-meter) antenna and lasted about two hours, with an additional four hours of tracking planned each day from November 6 - 10.

NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program at NASA's Jet Propulsion Laboratory in Pasadena, California, commonly called "Spaceguard," discovers these objects, characterizes some of them, and plots their orbits to determine if any could be potentially hazardous to our planet. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington.

Photo credit: NASA/JPL-Caltech

Jupiter and Io

Jupiter's four largest satellites, including Io, the golden ornament in front of Jupiter in this image from NASA's Cassini spacecraft, have fascinated Earthlings ever since Galileo Galilei discovered them in 1610 in one of his first astronomical uses of the telescope. This true-color composite frame, made from narrow angle images taken on December 12, 2000, captures Io and its shadow in transit against the disk of Jupiter. The distance of the spacecraft from Jupiter was 19.5 million kilometers. The image scale of the high resolution image is 117 kilometers per pixel. The entire body of Io, about the size of Earth's Moon, is periodically flexed as it speeds around Jupiter and feels, as a result of its non-circular orbit, the periodically changing gravitational pull of the planet. The heat arising in Io's interior from this continual flexure makes it the most volcanically active body in the solar system, with more than 100 active volcanoes. The white and reddish colors on its surface are due to the presence of different sulfurous materials. The black areas are silicate rocks.

Photo credit: NASA/JPL/University of Arizona

Hurricane Rina from the ISS

External cameras on the International Space Station captured views of Hurricane Rina at 2:39 p.m. EDT on October 25, 2011, as the complex flew 248 miles over the Caribbean Sea east of Belize. The late season hurricane, which continues to intensify, was located 300 miles east-southeast of Chetumal, Mexico, barely moving west-northwest at a glacial three miles an hour. Rina is packing winds of 105 miles an hour, and is forecast to intensify to a major hurricane as it approaches the Yucatan Peninsula. Hurricane warnings have been issued for the Yucatan from north of Punta Gruesa, Mexico, to Cancun.

Video credit: NASA

Half-Moon

This image of the Moon was taken with by Rosetta's OSIRIS Narrow Angle Camera (NAC) at 07:36 CET on 13 November 2007, about nine hours after Rosetta's closest approach to Earth during one of its gravity assist maneuvers.

OSIRIS has been designed to image faint objects, so a neutral density filter was placed in the optical path to reduce the sensitivity of the camera to one fiftieth. The above image was acquired through the far-focus red filter of the camera (750 nanometers).

Photo credit: ESA ©2007 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Gravitationally Lensed Quasar HE 1104-1805

This picture shows a quasar that has been gravitationally lensed by a galaxy in the foreground, which can be seen as a faint shape around the two bright images of the quasar.

Observations of one of the images show variations in color over time. This is caused by stars within the lens galaxy passing through the path of the light from the quasar, magnifying the light from different parts of the quasar's accretion disc as they move. This has allowed a team of scientists to reconstruct the color and temperature profile of the accretion disc with unprecedented precision. The level of detail involved is equivalent to being able to study individual grains of sand on the surface of the Moon while standing on Earth.

Photo credit: NASA, ESA and J.A. Muñoz (University of Valencia)

Note: For more information, see Hubble Directly Observes the Disc Around a Black Hole.

A Gamma Ray Burst Through Two Early Galaxies

This artist’s impression shows two galaxies in the early Universe. The brilliant explosion on the left is a gamma-ray burst. The light from the burst travels through both galaxies on its way to Earth (outside the frame to the right). Analysis of observations of the light from this gamma-ray burst made using ESO’s Very Large Telescope have shown that these two galaxies are remarkably rich in heavier chemical elements.

Illustration credit: ESO/L. Calçada

Note: For more information, see VLT Observations of Gamma-ray Burst Reveal Surprising Ingredients of Early Galaxies.

Vesta Crater and Ejecta in Visible and Infrared Wavelengths

Above are three different composite images of the same region of Vesta's surface. These images were produced by combining images obtained by the Visible and Infrared Imaging Spectrometer (VIR) instrument aboard NASA's Dawn spacecraft. The VIR instrument can image Vesta in many different wavelength regions, called bands, in the near ultraviolet, visible and infrared parts of the electromagnetic spectrum, which corresponds to a wavelength range of 300nm to 5000nm. The top image is a RGB composite simulated true color image where red is set as the 700nm band, green is set as the 550nm band and blue is set as the 440nm band. The wavelength of red light is around 700nm, of green light is around 550nm and of blue light is around 440nm, so this image approximates what the human eye would see looking at Vesta. The middle image is taken in the infrared part of the spectrum and shows the thermal emission of Vesta's surface; the light colors correspond to the hottest temperatures and the dark colors correspond to the coldest temperatures. The bottom image is another RGB composite image in which bands from the visible and infrared were combined to enhance the differences in the composition of Vesta's surface. In the case of this bottom image different colors correspond to characteristics of the composition of the surface. Different compositions can help to identify regions which have undergone different geological processes. For example, in the bottom image the green ejecta blanket of the crater on the right is very distinctive against the blue and red surface of the rest of Vesta. This ejecta blanket is much harder to identify in the other images.

Photo credit: NASA/JPL-Caltech/UCLA/ASI/INAF/IASF/IFSI

A Star with Spiral Arms

For more than four hundred years, astronomers have used telescopes to study the great variety of stars in our galaxy. Millions of distant suns have been cataloged. There are dwarf stars, giant stars, dead stars, exploding stars, binary stars; by now, you might suppose that every kind of star in the Milky Way had been seen.

That's why a recent discovery is so surprising. Researchers using the Subaru telescope in Hawaii have found a star with spiral arms.

The name of the star is SAO 206462. It's a young star more than four hundred light years from Earth in the constellation Lupus, the wolf. SAO 206462 attracted attention because it has a circumstellar disk--that is, a broad disk of dust and gas surrounding the star. Researchers strongly suspected that new planets might be coalescing inside the disk, which is about twice as wide as the orbit of Pluto.

When they took a closer look at SAO 206462 they found not planets, but arms. Astronomers have seen spiral arms before: they’re commonly found in pinwheel galaxies where hundreds of millions of stars spiral together around a common core. Finding a clear case of spiral arms around an individual star, however, is unprecedented1.

The arms might be a sign that planets are forming within the disk.

"Detailed computer simulations have shown us that the gravitational pull of a planet inside a circumstellar disk can perturb gas and dust, creating spiral arms,” says Carol Grady, an astronomer with Eureka Scientific, Inc., who is based at NASA's Goddard Space Flight Center. “Now, for the first time, we're seeing these dynamical features."

Grady revealed the image to colleagues on October 19th at a meeting at Goddard entitled Signposts of Planets.

Theoretical models show that a single embedded planet may produce a spiral arm on each side of a disk. The structures around SAO 206462, however, do not form a matched pair, suggesting the presence of two unseen worlds, one for each arm.

Grady's research is part of a five-year international study of newborn stars and planets using the giant 8.2 meter Subaru Telescope. Operated by the National Astronomical Observatory of Japan, Subaru scans the heavens from a perch almost 14,000 feet above sea level at the summit of the Hawaiian volcano Mauna Kea. From there it has a crystal-clear view of innumerable young stars and their planet-forming disks throughout the Milky Way.

"What we're finding is that once these systems reach ages of a few million years—that’s young for a star--their disks begin to show all kinds of interesting shapes,” says John Wisniewski, a collaborator at the University of Washington in Seattle. "We’ve seen rings, divots, gaps--and now spiral features. Many of these structures could be caused by planets moving within the disks."

However, it is not an open and shut case. The research team cautions that processes unrelated to planets might give rise to these structures. Until more evidence is collected--or until the planets themselves are detected--they can’t be certain.

Whatever the cause of the arms, their reality is undeniable and the great catalog of stars has one more type.

Text credit: NASA; photo credit: NAOJ/Subaru