Artist's Conception of a Protoplanetary Collision

Planets, including those like our own Earth, form from epic collisions between asteroids and even bigger bodies, called proto-planets. Sometimes the colliding bodies are ground to dust, and sometimes they stick together to ultimately form larger, mature planets.

This artist's conception shows one such smash-up, the evidence for which was collected by NASA's Spitzer Space Telescope. Spitzer's infrared vision detected a huge eruption around the star NGC 2547-ID8 between August 2012 and 2013. Scientists think the dust was kicked up by a massive collision between two large asteroids. They say the smashup took place in the star's "terrestrial zone," the region around stars where rocky planets like Earth take shape.

NGC 2547-ID8 is a sun-like star located about 1,200 light-years from Earth in the constellation Vela. It is about 35 million years old, the same age our young sun was when its rocky planets were finally assembled via massive collisions -- including the giant impact on proto-Earth that led to the formation of the moon. The recent impact witnessed by Spitzer may be a sign of similar terrestrial planet building. Near-real-time studies like these help astronomers understand how the chaotic process works.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see PIA18470: Witnessing a Planetary Wreckage and NASA's Spitzer Telescope Witnesses Asteroid Smashup.

Dust Ring Around HR 4796A

This infrared image shows the dust ring around the nearby star HR 4796A in the southern constellation of Centaurus. It was one of the first produced by the SPHERE instrument soon after it was installed on ESO’s Very Large Telescope in May 2014. It shows not only the ring itself with great clarity, but also reveals the power of SPHERE to reduce the glare from the very bright star — the key to finding and studying exoplanets in future.

Image credit: ESO/J.-L. Beuzit et al./SPHERE Consortium

Note: For more information, see First Light for SPHERE Exoplanet Imager.

Kepler-10c

An artist's conception shows the Kepler-10 system, home to two rocky planets. In the foreground is Kepler-10c, a planet that weighs 17 times as much as Earth and is more than twice as large in size. Planet formation theorists are challenged to explain how such a massive world could have formed.

Image credit: Harvard-Smithsonian Center for Astrophysics/David Aguilar

Note: For more information, see Astronomers Confounded By Massive Rocky World.

Planetary Formation Through Magnetic Fields

Magnetic loops carry gas and dust above disks of planet-forming material circling stars, as shown in this artist's conception. These loops give off extra heat, which NASA's Spitzer Space Telescope detects as infrared light. The colors in this illustration show what an alien observer with eyes sensitive to both visible light and infrared wavelengths might see.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see Mystery of Planet-forming Disks Explained by Magnetism.

Structural Composition of Asteroid 25143 Itokawa

A schematic view of the strange peanut-shaped asteroid Itokawa.

By making exquisitely precise timing measurements using ESO’s New Technology Telescope, and combining them with a model of the asteroid's surface topography, a team of astronomers has found that different parts of this asteroid have different densities. As well as revealing secrets about the asteroid’s formation, finding out what lies below the surface of asteroids may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form. The shape model used for this view is based on the images collected by JAXA's Hayabusa spacecraft.

This very detailed view shows the strange peanut-shaped asteroid Itokawa. By making exquisitely precise timing measurements using ESO’s New Technology Telescope a team of astronomers has found that different parts of this asteroid have different densities. As well as revealing secrets about the asteroid’s formation, finding out what lies below the surface of asteroids may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form.

This picture comes from the Japanese spacecraft Hayabusa during its close approach in 2005.

Top illustration credit: ESO. Acknowledgement: JAXA. Bottom photo credit: JAXA

Note: For more information, see The Anatomy of an Asteroid.

Silicate Worlds vs Carbon Worlds

This artist's concept illustrates the fate of two different planets: the one on the left is similar to Earth, made up largely of silicate-based rocks with oceans coating its surface. The one on the right is rich in carbon -- and dry. Chances are low that life as we know it, which requires liquid water, would thrive under such barren conditions.

New theoretical findings show that planetary systems with carbon-rich stars would host waterless rocky planets. On Earth, it is believed that icy asteroids and comets are the main suppliers of Earth's ocean. But, in star systems rich in carbon, the carbon would snag up oxygen to make carbon monoxide, leaving little oxygen to make water ice. In those systems, the asteroids and comets would be dry.

The most extreme carbon-rich stars, with much more carbon than our sun, are thought to create carbon-based planets, as depicted in this illustration. Those planets would lack oceans due to a lack of icy asteroids and comets serving as water reservoirs.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see Carbon Worlds May be Waterless, Finds NASA Study.

"Blinking" Binary Star System YLW 16A

In this artist's impression, a disk of dusty material leftover from star formation girds two young stars like a hula hoop. As the two stars whirl around each other, they periodically peek out from the disk, making the system appear to "blink" every 93 days.

The dusty hula hoop itself is misaligned from the central star pair, thanks to the disrupting gravitational presence of a third star orbiting at the periphery of the system. The light yellow arcs near the two central stars indicate their movement relative to each other and the disk. It is believed that this disk will go on to spawn planets and the other celestial bodies that make up a solar system.

NASA's Spitzer Space Telescope observed this system, called YLW 16A, in the infrared light emitted by the disk's warmed gas and dust.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see Spitzer Discovers Young Stars with a 'Hula Hoop.'

Comet Ison by Spitzer

These images from NASA's Spitzer Space Telescope of C/2012 S1 (Comet ISON) were taken on June 13, when ISON was 310 million miles (about 500 million kilometers) from the sun. The images were taken with the telescope's infrared array camera at two different near-infrared wavelengths, 3.6 and 4.5 microns (the representational colors shown were selected to enhance visibility). The 3.6-micron image on the left shows a tail of fine rocky dust issuing from the comet and blown back by the pressure of sunlight as the comet speeds towards the sun (the tail points away from the sun). The image on the right side shows the 4.5-micron image with the 3.6-micron image information (dust) removed, and reveals a very different round structure -- the first detection of a neutral gas atmosphere surrounding ISON. In this case, it is most likely created by carbon dioxide that is "fizzing" from the surface of the comet at a rate of about 2.2 million pounds (1 million kilograms) a day.

Comet ISON (officially known as C/2012 S1) is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. ISON will pass within 724,000 miles (1.2 million kilometers) of the sun on November 28, making it a sungrazer comet that will evaporate its ices and even its rocky dust near perihelion, revealing even more of the comet's composition.

Image credit: NASA/JPL-Caltech/JHUAPL/UCF

Note: For more information, see NASA's Spitzer Observes Gas Emission From Comet ISON.

Snow Rings Around TW Hydrae

An artist's concept of the snow line in TW Hydrae showing water ice covered dust grains in the inner disc (4.5–30 astronomical units, blue) and carbon monoxide ice covered grains in the outer disc (>30 astronomical units, green). The transition from blue to green marks the carbon monoxide snow line. The snow helps grains of dust to adhere to each other by providing a sticky coating, which is essential to the formation of planets and comets. Due to the different freezing points of different chemical compounds, different snow lines can be found at various distances from the star.

This ALMA image shows the region where carbon monoxide snow has formed around the star. The carbon monoxide is shown here in green, and begins at a distance of more than 30 astronomical units from TW Hydrae. Aside from being necessary for planetary and comet formation, carbon monoxide is needed for the creation of methanol which is a fundamental building block required for life.

Credit: (top) B. Saxton & A. Angelich/NRAO/AUI/NSF/ALMA (ESO/NAOJ/NRAO); (bottom) ALMA (ESO/NAOJ/NRAO)

Note: For more information, see Snow in an Infant Planetary System.

Herschel Completes Its 'Cool' Journey in Space

Andromeda, also known as M31, is the nearest major galaxy to our own Milky Way.

The Herschel observatory, a European space telescope for which NASA helped build instruments and process data, has stopped making observations after running out of liquid coolant as expected.

The European Space Agency mission, launched almost four years ago, revealed the universe's "coolest" secrets by observing the frigid side of planet, star and galaxy formation.

"Herschel gave us the opportunity to peer into the dark and cold regions of the universe that are invisible to other telescopes," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate at NASA headquarters in Washington. "This successful mission demonstrates how NASA and ESA can work together to tackle unsolved mysteries in astronomy."

Confirmation the helium is exhausted came today, at the beginning of the spacecraft's daily communication session with its ground station in Western Australia. A clear rise in temperatures was measured in all of Herschel's instruments.

Herschel launched aboard an Ariane 5 rocket from French Guiana in May 2009. NASA's Jet Propulsion Laboratory in Pasadena, California, built components for two of Herschel's three science instruments. NASA also supports the U.S. astronomical community through the agency's Herschel Science Center, located at the California Institute of Technology's Infrared Processing and Analysis Center in Pasadena.

Herschel's detectors were designed to pick up the glow from celestial objects with infrared wavelengths as long as 625 micrometers, which is 1,000 times longer than what we can see with our eyes. Because heat interferes with these devices, they were chilled to temperatures as low as 2 kelvins (minus 271 degrees Celsius, or 456 Fahrenheit) using liquid helium. The detectors also were kept cold by the spacecraft's orbit, which is around a stable point called the second Lagrange point about 930,000 miles (1.5 million kilometers) from Earth. This location gave Herschel a better view of the universe.

"Herschel has improved our understanding of how new stars and planets form, but has also raised many new questions," said Paul Goldsmith, NASA Herschel project scientist at JPL. "Astronomers will be following up on Herschel's discoveries with ground-based and future space-based observatories for years to come."

The mission will not be making any more observations, but discoveries will continue. Astronomers still are looking over the data, much of which already is public and available through NASA's Herschel Science Center. The final batch of data will be public in about six months.

"Our goal is to help the U.S. community exploit the nuggets of gold that lie in that data archive," said Phil Appleton, project scientist at the science center.

Highlights of the mission include:

-- Discovering long, filamentary structures in space, dotted with dense star-making knots of material.
-- Detecting definitively, for the first time, oxygen molecules in space, in addition to other never-before-seen molecules. By mapping the molecules in different regions, researchers are learning more about the life cycles of stars and planets and the origins of life.
-- Discovering high-speed outflows around central black holes in active galaxies, which may be clearing out surrounding regions and suppressing future star formation.
-- Opening new views on extremely distant galaxies that could be seen only with Herschel, and providing new information about their high rates of star formation.
-- Following the trail of water molecules from distant galaxies to the clouds of gas between stars to planet-forming solar systems.
-- Examining a comet in our own solar system and finding evidence comets could have brought a substantial fraction of water to Earth.
-- Together with NASA's Spitzer Space Telescope, discovering a large asteroid belt around the bright star Vega.

Other findings from the mission include the discovery of some of the youngest stars ever seen in the nearby Orion "cradle," and a peculiar planet-forming disk of material surrounding the star TW Hydra, indicating planet formation may happen over longer periods of time than expected. Herschel also has shown stars interact with their environment in many surprising ways, including leaving trails as they move through clouds of gas and dust.

Photo credit: ESA/Herschel/PACS & SPIRE Consortium, O. Krause, HSC, H. Linz

Note: For more information, see Observation Gives Way to Examination as Herschel Coolant Runs Out.

Protoplanetary Disk Around TW Hydrae

This illustration depicts the protoplanetary disc around the nearby young star TW Hydrae. With an age of about ten million years, TW Hydrae is located about 180 light-years away, towards the constellation Hydra, or the Sea Serpent.

Protoplanetary discs form around young stars from leftover material from the stellar formation process, which consists mainly of molecular hydrogen gas. This material orbits the star in a protoplanetary disc for several millions of years before it condenses into planets or is dispersed away by winds driven by the radiation of the star. In addition, trace amounts of cosmic dust and other gas species are present in the disc.

Astronomers using ESA's Herschel Space Observatory detected heavy molecular hydrogen in the protoplanetary disc around TW Hydrae, and have used this molecule as a tracer of the disc's main constituent – molecular hydrogen. This study has yielded the first accurate determination of the mass of a protoplanetary disc. With a mass equivalent to 50 times that of Jupiter, the disc around TW Hydrae is several times more massive than the primordial disc that gave birth to our Solar System.

At about ten million years, TW Hydrae is a relatively young star, but quite old to have retained a massive protoplanetary disc. The extremely accurate estimate of the disc's mass will benefit future observations of TW Hydrae and its environment, as astronomers investigate the various scenarios that could eventually lead to the formation of planets around this star.

Illustration credit: ESA/C. Carreau

Note: For more information, see Herschel Sizes Up Massive Protoplanetary Disc. Also, see PIA16683: Weighing Planetary Disks and Herschel Finds Past-Prime Star May Be Making Planets. Another post about TW Hydrae can be found here: Misty Star in the Sea Serpent.

ALMA Observations of the Disc and Gas Streams Around HD 142527

Observations made with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope of the disc of gas and cosmic dust around the young star HD 142527, showing vast streams of gas flowing across the gap in the disc. These are the first direct observations of these streams, which are expected to be created by giant planets guzzling gas as they grow, and which are a key stage in the birth of giant planets.

The dust in the outer disc is shown in red. Dense gas in the streams flowing across the gap, as well as in the outer disc, is shown in green. Diffuse gas in the central gap is shown in blue. The gas filaments can be seen at the three o'clock and ten o'clock positions, flowing from the outer disc towards the center. The dense gas observed is HCO+, and the diffuse gas is CO. The outer disk is roughly two light-days across. If this were our own Solar System, the Voyager 1 probe — the most distant manmade object from Earth — would be at approximately the inner edge of the outer disk.

Image credit: ALMA (ESO/NAOJ/NRAO), S. Casassus et al.

Note: For more information, see ALMA Sheds Light on Planet-Forming Gas Streams.

Protoplanetary Disk Around a Brown Dwarf Star

This artist’s impression shows the disc of gas and cosmic dust around a brown dwarf.

Rocky planets are thought to form through the random collision and sticking together of what are initially microscopic particles in the disc of material around a star. These tiny grains, known as cosmic dust, are similar to very fine soot or sand. Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have for the first time found that the outer region of a dusty disc encircling a brown dwarf — a star-like object, but one too small to shine brightly like a star — also contains millimeter-sized solid grains like those found in denser discs around newborn stars. The surprising finding challenges theories of how rocky, Earth-scale planets form, and suggests that rocky planets may be even more common in the Universe than expected.

Illustration credit: ALMA (ESO/NAOJ/NRAO)/M. Kornmesser (ESO)

Note: For more information, see Even Brown Dwarfs May Grow Rocky Planets.

TYC 8241 2652: The Mysterious Case of the Disappearing Dust

Imagine if the rings of Saturn suddenly disappeared. Astronomers have witnessed the equivalent around a young sun-like star called TYC 8241 2652. Enormous amounts of dust known to circle the star are unexpectedly nowhere to be found.

"It's like the classic magician's trick: now you see it, now you don't. Only in this case we're talking about enough dust to fill an inner solar system and it really is gone!" said Carl Melis of the University of California, San Diego, who led the new study appearing in the July 5 issue of the journal Nature.

A dusty disk around TYC 8241 2652 was first seen by the NASA Infrared
Astronomical Satellite (IRAS) in 1983, and continued to glow brightly for 25 years. The dust was thought to be due to collisions between forming planets, a normal part of planet formation. Like Earth, warm dust absorbs the energy of visible starlight and reradiates that energy as infrared, or heat, radiation.

The first strong indication of the disk's disappearance came from images taken in January 2010 by NASA's Wide-field Infrared Survey Explorer, or WISE. An infrared image obtained at the Gemini telescope in Chile on May 1, 2012, confirmed that the dust has now been gone for two-and-a-half years.

"Nothing like this has ever been seen in the many hundreds of stars that astronomers have studied for dust rings," said co-author Ben Zuckerman of UCLA, whose research is funded by NASA. "This disappearance is remarkably fast even on a human time scale, much less an astronomical scale. The dust disappearance at TYC 8241 2652 was so bizarre and so quick, initially I figured that our observations must simply be wrong in some strange way."

The astronomers have come up with a couple of possible solutions to the mystery, but they say none are compelling. One possibility is that gas produced in the impact that released the dust helped to quickly drag the dust particles into the star and thus to their doom. In another possibility, collisions of large rocks left over from an original major impact provide a fresh infusion of dust particles into the disk, which caused the dust grains to chip apart into smaller and smaller pieces.

The result is based upon multiple sets of observations of TYC 8241 2652 obtained with the Thermal-Region Camera Spectrograph on the Gemini South telescope in Chile; IRAS; WISE; NASA's Infrared Telescope on Mauna Kea in Hawaii; the European Space Agency's Herschel Space Telescope, in which NASA plays an important role; and the Japanese/European Space Agency AKARI infrared satellite.

Illustration credit: NASA/JPL-Caltech

Artist's Impression of the Brown Dwarf 2M1207

This illustration shows an artist's impression of the brown dwarf 2MASSW J1207334-393254, or 2M1207 for short. With a mass that amounts to 25 times that of Jupiter, 2M1207 is surrounded by a circumstellar disc of gas and dust and possesses a planetary companion five times more massive than Jupiter. The planetary companion lies at a very large distance from 2M1207 – the projected distance between the two bodies measuring 55 astronomical units (AU).

Sub-millimeter observations performed with the SPIRE instrument on board ESA's Herschel Space Observatory have shown that the disc's total mass amounts to about three to five times the mass of Jupiter and that its radius ranges between 50 and 100 AU. With such a massive disc, it is likely that the planetary-mass companion originated directly from disc fragmentation, thus challenging the standard scenario of giant planet formation via core accretion.

Illustration credit: ESA

Note: For more information, see Herschel's New View on Giant Planet Formation.

Abell 2052

The galaxy cluster Abell 2052 is found some 480 million light years from Earth. At the center of Abell 2052 is a giant elliptical galaxy, and within that is a supermassive black hole. X-ray data from Chandra show the hot gas that fills the space within the cluster. Pulling away, we see a huge spiral structure around this central elliptical galaxy. This spiral, which is over one million light years across, was created when a smaller spiral smashed into Abell 2052. This caused the hot gas in the cluster to slosh back and forth, similar to how wine moves when a glass is tugged from side to side. This sloshing turns out to be very important. First, it helps redistribute the hot gas, which, in turn, affects the number of new stars being formed in the central galaxy. The sloshing also spreads elements like oxygen and iron throughout the cluster, enriching future generations of stars and planets with the building blocks necessary for life as we know it.

Video credit: NASA/CXC/A. Hobart

Note: For more information, see Abell 2052: A Galaxy Cluster Gets Sloshed

Is Vesta the "Smallest Terrestrial Planet?"

NASA's Dawn spacecraft spent the last four years voyaging to asteroid Vesta – and may have found a planet.

Vesta was discovered over two hundred years ago but, until Dawn, has been seen only as an indistinct blur and considered little more than a large, rocky body. Now the spacecraft's instruments are revealing the true complexity of this ancient world.

"We're seeing enormous mountains, valleys, hills, cliffs, troughs, ridges, craters of all sizes, and plains," says Chris Russell, Dawn principal investigator from UCLA. "Vesta is not a simple ball of rock. This is a world with a rich geochemical history. It has quite a story to tell!"

In fact, the asteroid is so complex that Russell and members of his team are calling it the "smallest terrestrial planet."

Vesta has an iron core, notes Russell, and its surface features indicate that the asteroid is "differentiated" like the terrestrial planets Earth, Mercury, Mars, and Venus.

Differentiation is what happens when the interior of an active planet gets hot enough to melt, separating its materials into layers. The light material floats to the top while the heavy elements, such as iron and nickel, sink to the center of the planet.

Researchers believe this process also happened to Vesta.

The story begins about 4.57 billion years ago, when the planets of the Solar System started forming from the primordial solar nebula. As Jupiter gathered itself together, its powerful gravity stirred up the material in the asteroid belt so objects there could no longer coalesce. Vesta was in the process of growing into a full-fledged planet when Jupiter interrupted the process.

Although Vesta’s growth was stunted, it is still differentiated like a true planet.

"We believe that the Solar System received an extra slug of radioactive aluminum and iron from a nearby supernova explosion at the time Vesta was forming," explains Russell. "These materials decay and give off heat. As the asteroid was gathering material up into a big ball of rock, it was also trapping the heat inside itself."

As Vesta’s core melted, lighter materials rose to the surface, forming volcanoes and mountains and lava flows.

"We think Vesta had volcanoes and flowing lava at one time, although we've not yet found any ancient volcanoes there," says Russell. "We're still looking. Vesta's plains seem similar to Hawaii's surface, which is basaltic lava solidified after flowing onto the surface.

Vesta has so much in common with the terrestrial planets, should it be formally reclassified from "asteroid" to "dwarf planet"?

"That's up to the International Astronomical Union, but at least on the inside, Vesta is doing all the things a planet does."

If anyone asks Russell, he knows how he would vote.

Text credit: NASA; video credit: NASA

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.

Misty Star in the Sea Serpent

This artist's concept illustrates an icy planet-forming disk around a young star called TW Hydrae, located about 175 light-years away in the Hydra, or Sea Serpent, constellation. Astronomers using the Herschel Space Observatory detected copious amounts of cool water vapor, illustrated in blue, emanating from the star's planet-forming disk of dust and gas. The water vapor, which probably comes from icy grains in the disk, is located in the frigid outer regions of the star system, where comets will take shape.

In our own solar system, comets are thought to have carried water to Earth, creating our oceans. A similar process might be taking place around TW Hydrae -- comets could, over the next several millions of years, transport water to young worlds. The Herschel results demonstrate that vast reservoirs of water are available around stars for creating these hypothetical water worlds.

The graph of data (Figure 1) from Herschel shows how the cool water vapor was detected. Water molecules come in two "spin" forms, called ortho and para, in which the two spins of the hydrogen nuclei have different orientations. In this case, the team compared the ratio of ortho to para water seen in the TW Hydrae disk to that in comets, and found very low values. Lower ratios indicate cooler temperatures, though in practice the analysis is much more complicated. This is the first demonstration that water exists in large quantities in the frigid, outer regions of solar systems, where comets take shape.

Illustration credit: ESA/NASA/JPL-Caltech/Leiden Observatory

Note: For more information, see Herschel Discovers Tip of Cosmic Iceberg Around Nearby Young Star.

Vesta

NASA's Hubble Space Telescope snapped these images of the asteroid Vesta in preparation for the Dawn spacecraft's visit in 2011.

Each of the four Hubble images captures views of Vesta during its 5.34-hour rotation period. Hubble's sharp "eye" can see features as small as about 40 kilometers (25 miles) across in these images. Vesta was 211 million kilometers (131 million miles) from Earth when Hubble made the observations.

The images show the difference in brightness and color on the asteroid's surface. These characteristics hint at the large-scale features that the Dawn spacecraft will see when it visits the potato-shaped asteroid.

Vesta is somewhat like our Moon, with ancient lava beds (the dark patches) and powdery debris, the pulverized remains of impacts (the orange-colored areas). The flattened area on one end of Vesta, visible in the top row of images, is a giant impact crater formed by a collision billions of years ago. The crater is 460 kilometers (285 miles) across, which is close to Vesta's roughly 530-kilometer (330-mile) diameter. Vesta is about the size of Arizona.

Astronomers used the images, taken with Hubble's Wide Field Camera 3, to better determine Vesta's spin axis. Based on the Hubble observations, astronomers calculated a slightly different, and more precise, rotation axis for Vesta. The new calculation will change the pattern of sunlight expected to illuminate the asteroid when Dawn arrives.

Determining a more accurate spin axis for Vesta will also help scientists refine the Dawn spacecraft's orbit around the asteroid. Dawn will orbit the rocky object for a year, beginning in July 2011. The spacecraft will then travel to the dwarf planet Ceres, arriving in 2015.

Vesta is one of the largest of a reservoir of about 100,000 asteroids, the leftover material from the formation of our solar system planets 4.6 billion years ago.

Hubble has kept its "eye" on Vesta for more than 15 years, beginning in 1994. Hubble images of Vesta in 1997 helped astronomers discover the asteroid's immense impact crater.

Astronomers combined views of Vesta in near-ultraviolet and blue light to construct these images. The images were taken on February 25, 2010.

Photo credit: NASA/ESA/STScI/UMd

Update: NASA has released a short video of Vesta rotating on its axis; the animation is made up of 146 pictures taken by the Hubble Space Telescope. The Minister cannot upload this video onto this post, but the story about the video can be read here (PIA13427: A New Spin on Vesta), and the video can be watched here.