Category: Hubble

After receiving complaints, NASA Administrator Sean O’Keefe has said he’s looking for a second opinion on what to do about the Hubble Space Telescope. NASA had recently announced that it would cancel the next servicing mission for the aging telescope, which will likely fail by 2007. O’Keefe is looking to retired Admiral Harold Gehman, who chaired the independent Columbia Accident Investigation Board. Gehman has yet to say if he’ll take up the task of investigating the case for Hubble.

Image credit: Hubble

New photographs from the Hubble Space Telescope show details of the atmospheres on Uranus and Neptune. The photos were taken using Hubble’s Imaging Spectrograph and Advanced Camera for Surveys in August 2003. Both planets have bands of clouds and haze lined up with the planets’ equators. Astronomers use different kinds of filters to reveal different kinds of gasses in the clouds, and even their altitudes above the planets.

Atmospheric features on Uranus and Neptune are revealed in images taken with the Space Telescope Imaging Spectrograph and the Advanced Camera for Surveys aboard NASA’s Hubble Space Telescope. The observations were taken in August 2003.

The top row reveals Uranus and Neptune in natural colors, showing the planets as they would appear if we could see them through a telescope. The images are made of exposures taken with filters sensitive to red, green, and blue light. In the bottom images, astronomers used different color filters to detect features we can’t see. The photographs demonstrate that, by using certain types of color filters, astronomers can extract more information about a celestial object than our eyes normally can see.

At first glance, the top row of images makes the planets appear like twins. But the bottom row reveals that Uranus and Neptune are two different worlds. Uranus’s rotational axis, for example, is tilted almost 90 degrees to Neptune’s axis. The south poles of Uranus and Neptune are at the left and bottom, respectively. Both are tilted slightly toward Earth. Uranus also displays more contrast between both hemispheres. This may be caused by its extreme seasons.

Both planets display a banding structure of clouds and hazes aligned parallel to the equator. Additionally, a few discrete cloud features appear bright orange or red. The color is due to methane absorption in the red part of the spectrum. Methane is third in abundance in the atmospheres of Uranus and Neptune after hydrogen and helium, which are both transparent. Colors in the bands correspond to variations in the altitude and thickness of hazes and clouds. The colors allow scientists to measure the altitudes of clouds from far away.

Original Source: Hubble News Release

NASA has canceled all space shuttle flights to service the Hubble Space Telescope, which has provided revolutionary astronomy data and photographs. The decision was influenced by President Bush’s new space initiative, which called for the space shuttle to be retired by 2010. Without a servicing mission, Hubble will continue to degrade over time, lasting at least until 2007 or 2008. When it finally does stop functioning, NASA will launch a robot thruster to de-orbit the school bus-sized observatory safely.

Image credit: Hubble

An international team of astronomers have gathered evidence that galaxies formed very quickly after the Big Bang. The team found a proto-galaxy cluster more than 12 billion light-years away – the galaxies are so young that astronomers can see a flurry of stars forming inside them. This means they’re only 1.5 billion years old, a time when the Universe was only 10% of its current age. It’s believed that these clusters formed so quickly because these areas were incredibly dense with material.

Looking back in time nearly 9 billion years, an international team of astronomers found mature galaxies in a young universe. The galaxies are members of a cluster of galaxies that existed when the universe was only 5 billion years old, or about 35 percent of its present age. This compelling evidence that galaxies must have started forming just after the big bang was bolstered by observations made by the same team of astronomers when they peered even farther back in time. The team found embryonic galaxies a mere 1.5 billion years after the birth of the cosmos, or 10 percent of the universe’s present age. The “baby galaxies” reside in a still-developing cluster, the most distant proto-cluster ever found.

The Advanced Camera for Surveys (ACS) aboard NASA’s Hubble Space Telescope was used to make observations of the massive cluster, RDCS 1252.9-2927, and the proto-cluster, TN J1338-1942. Observations by NASA’s Chandra X-ray Observatory yielded the mass and heavy element content of RDCS 1252, the most massive known cluster for that epoch. These observations are part of a coordinated effort by the ACS science team to track the formation and evolution of clusters of galaxies over a broad range of cosmic time. The ACS was built especially for studies of such distant objects.

These findings further support observations and theories that galaxies formed relatively early in the history of the cosmos. The existence of such massive clusters in the early universe agrees with a cosmological model wherein clusters form from the merger of many sub-clusters in a universe dominated by cold dark matter. The precise nature of cold dark matter, however, is still not known.

The first Hubble study estimated that galaxies in RDCS 1252 formed the bulk of their stars more than 11 billion years ago (at redshifts greater than 3). The results were published in the Oct. 20, 2003 issue of the Astrophysical Journal. The paper’s lead author is John Blakeslee of the Johns Hopkins University in Baltimore, Md.

The second Hubble study uncovered, for the first time, a proto-cluster of “infant galaxies” that existed more than 12 billion years ago (at redshift 4.1). These galaxies are so young that astronomers can still see a flurry of stars forming within them. The galaxies are grouped around one large galaxy. These results will be published in the Jan. 1, 2004 issue of Nature. The paper’s lead author is George Miley of Leiden Observatory in the Netherlands.

“Until recently people didn’t think that clusters existed when the universe was only about 5 billion years old,” Blakeslee explained.

“Even if there were such clusters,” Miley added, “until recently astronomers thought it was almost impossible to find clusters that existed 8 billion years ago. In fact, no one really knew when clustering began. Now we can witness it.”

Both studies led the astronomers to conclude that these systems are the progenitors of the galaxy clusters seen today. “The cluster RDCS 1252 looks like a present-day cluster,” said Marc Postman of the Space Telescope Science Institute in Baltimore, Md., and co-author of both research papers. “In fact, if you were to put it next to a present-day cluster, you wouldn’t know which is which.”

A Tale of Two Clusters

How can galaxies grow so fast after the big bang? “It is a case of the rich getting richer,” Blakeslee said. “These clusters grew quickly because they are located in very dense regions, so there is enough material to build up the member galaxies very fast.”

This idea is strengthened by X-ray observations of the massive cluster RDCS 1252. Chandra and the European Space Agency’s XMM-Newton provided astronomers with the most accurate measurements to date of the properties of an enormous cloud of hot gas that pervades the massive cluster. This 160-million-degree Fahrenheit (70-million-degree Celsius) gas is a reservoir of most of the heavy elements in the cluster and an accurate tracer of its total mass. A paper by Piero Rosati of the European Southern Observatory (ESO) and colleagues that presents the X-ray observations of RDCS 1252 will be published in January 2004 in the Astronomical Journal.

“Chandra’s sharp vision resolved the shape of the hot gas halo and showed that RDCS 1252 is very mature for its age,” said Rosati, who discovered the cluster with the ROSAT X-ray telescope.

RDCS 1252 may contain many thousands of galaxies. Most of these galaxies, however, are too faint to detect. But the powerful “eyes” of the ACS pinpointed several hundred of them. Observations using ESO’s Very Large Telescope (VLT) provided a precise measurement of the distance to the cluster. The ACS enabled the researchers to accurately determine the shapes and colors of the 100 galaxies, providing information on the ages of the stars residing in them. The ACS team estimated that most of the stars in the cluster were already formed when the universe was about 2 billion years old. X-ray observations, furthermore, showed that 5 billion years after the big bang the surrounding hot gas had been enriched with heavy elements from these stars and had been swept away from the galaxies.

If most of the galaxies in RDCS 1252 have reached maturity and are settling into a quiet adulthood, the forming galaxies in the distant proto-cluster are in their energetic, unruly youth.

The proto-cluster TN J1338 contains a massive embryonic galaxy surrounded by smaller developing galaxies, which look like dots in the Hubble image.

The dominant galaxy is producing spectacular radio-emitting jets, fueled by a supermassive black hole deep within the galaxy’s nucleus. Interaction between these jets and the gas can stimulate a torrent of star birth.

The energetic radio galaxy’s discovery by radio telescopes prompted astronomers to hunt for the smaller galaxies that make up the bulk of the cluster.

“Massive clusters are the cities of the universe, and the radio galaxies within them are the smokestacks we can use for finding them when they are just beginning to form,” Miley said.

The two findings underscore the power of combining observations from many different telescopes that provided views of the distant universe in a range of wavelengths. Hubble’s advanced camera provided critical information on the structure of both distant galaxy clusters. Chandra’s and XMM-Newton’s X-ray vision furnished the essential measurements of the primordial gas in which the galaxies in RDCS 1252 are embedded, and accurate estimates of the total mass contained within that cluster. Large ground-based telescopes, like the VLT, provided precise measurements of the distance of both clusters as well as the chemical composition of the galaxies in them.

The ACS team is conducting further observations of distant clusters to solidify our understanding of how these young clusters and their galaxies evolve into the shape of things seen today. Their planned observations include using near-infrared observations to analyze the star-formation rates in some of the target clusters, including RDCS 1252, to measure the cosmic history of star formation in these massive structures. The team is also searching the regions around several ultra-distant radio galaxies for additional examples of proto-clusters. The team’s ultimate scientific goal is to establish a complete picture of cluster evolution beginning with the formation at the earliest epochs and detailing the evolution up to today.

Original Source: Hubble News Release

Image credit: Hubble

The Hubble Space Telescope took this incredible photograph of nebula NGC 604, which is a huge area of newly forming stars in galaxy M33. The area is similar to the star forming region in the Orion Nebula, but it’s 100 times larger. The most massive stars in the nebula are 120 times the mass of the Sun and their surface temperatures exceed 40,000 degrees Kelvin. Intense ultraviolet radiation floods out of these stars, which lights up the surrounding gas. NGC 604 is 2.7 million light-years away in the constellation Triangulum.

This festively colorful nebula, called NGC 604, is one of the largest known seething cauldrons of star birth in a nearby galaxy. NGC 604 is similar to familiar star-birth regions in our Milky Way galaxy, such as the Orion Nebula, but it is vastly larger in extent and contains many more recently formed stars.

This monstrous star-birth region contains more than 200 brilliant blue stars within a cloud of glowing gases some 1,300 light-years across, nearly 100 times the size of the Orion Nebula. By contrast, the Orion Nebula contains just four bright central stars. The bright stars in NGC 604 are extremely young by astronomical standards, having formed a mere 3 million years ago.

Most of the brightest and hottest stars form a loose cluster located within a cavity near the center of the nebula. Stellar winds from these hot blue stars, along with supernova explosions, are responsible for carving out the hole at the center. The most massive stars in NGC 604 exceed 120 times the mass of our Sun, and their surface temperatures are as hot as 72,000 degrees Fahrenheit (40,000 Kelvin). Ultraviolet radiation floods out from these hot stars, making the surrounding nebular gas fluoresce.

NGC 604 lies in a spiral arm of the nearby galaxy M33, located about 2.7 million light-years away in the direction of the constellation Triangulum. M33, a member of the Local Group of galaxies that also includes the Milky Way and the Andromeda Galaxy, can be seen easily with binoculars. NGC 604 itself can be seen with a small telescope, and was first noted by the English astronomer William Herschel in 1784. Within our Local Group, only the Tarantula Nebula in the Large Magellanic Cloud exceeds NGC 604 in the number of young stars, even though the Tarantula Nebula is slightly smaller in size.

NGC 604 provides Hubble astronomers with a nearby example of a giant star-birth region. Such regions are small-scale versions of more distant “starburst” galaxies, which undergo an extremely high rate of star formation. Starbursts are believed to have been common in the early universe, when the star-formation rate was much higher. Supernovae exploding in these galaxies created the first chemical elements heavier than hydrogen and helium.

The image of NGC 604 was assembled from observations taken with Hubble’s Wide Field Planetary Camera 2 in 1994, 1995, and 2001. Color filters were used to isolate light emitted by hydrogen, oxygen, nitrogen, and sulfur atoms in the nebula and ultraviolet, visible and infrared light from the stars within NGC 604 and the nearby spiral arms of M33. Image processors from the Hubble Heritage team at the Space Telescope Science Institute combined these various filter images to create this color picture.

Original Source: Hubble News Release

Image credit: Hubble

The newest image released from the Hubble Space Telescope shows a turbulent region of space surrounding an ultra-luminous star called Eta Carinae. The strand-like nature of the nebula was caused by a series of stars that blew off their outer shells – some of the brighter areas in the nebula may eventually turn into new star systems. This picture is only a three light-year chunk of the whole Carina Nebula, which is 200 light-years across and visible to the naked eye in the southern sky.

A small portion of the rough-and-tumble neighborhood of swirling dust and gas near one of the most massive and eruptive stars in our galaxy is seen in this NASA Hubble Space Telescope image. This close-up view shows only a three light-year-wide portion of the entire Carina Nebula, which has a diameter of over 200 light-years. Located 8,000 light-years from Earth, the nebula can be seen in the southern sky with the naked eye.

Dramatic dark dust knots and complex structures are sculpted by the high-velocity stellar winds and high-energy radiation from the ultra-luminous variable star called Eta Carinae, or Eta Car (located outside the picture). This image shows a region in the Carina Nebula between two large clusters of some of the most massive and hottest known stars.

The filamentary structure is caused by turbulence in the circumstellar gas, which in turn was caused by several stars shedding their outer layers. Cold gas mixes with hot gas, leaving a veil of denser, opaque material in the foreground. The chemical elements in the surroundings create a potential reservoir for new star formation. Areas in the brightest parts of the image at the top show elephant-trunk shaped dust clouds that may form into embryonic solar systems.

This Hubble image was taken in July 2002 as part of a parallel observing program. The Hubble telescope has several instruments that can be simultaneously used to look at slightly different portions of the sky. In this case, the Space Telescope Imaging Spectrograph was used to study Eta Carinae itself, while the Wide Field Planetary Camera 2 was used to take this image of the nebulosity near Eta Car. This parallel observing mode increases Hubble’s efficiency and allows astronomers to probe parts of the sky that they would not otherwise be able to investigate.

Produced by the Hubble Heritage team, this color image is a composite of ultraviolet, visible, and infrared filters that have been assigned the colors blue, green, and red, respectively.

Original Source: Hubble News Release

Image credit: ESA

The Hubble Space Telescope was recently used to peer into a star forming region that’s a million times more active than the Orion Nebula. The Lynx Arc contains a million blue-white stars (the Orion Nebula has four) which are twice as hot as similar stars in our own Milky Way galaxy; but this cluster is located 12 billion light-years away, and seen when the Universe was only 2 billion years old. This discovery will help astronomers understand how some of the first stars formed shortly after the Big Bang.

A mysterious arc of light found behind a distant cluster of galaxies has turned out to be the biggest, brightest and hottest star-forming region ever seen in space.

The so-called Lynx Arc is one million times brighter than the well-known Orion Nebula, a nearby prototypical ?starbirth? region visible with small telescopes. The newly identified super-cluster contains a million blue-white stars that are twice as hot as similar stars in our Milky Way galaxy. It is a rarely glimpsed example of the early days of the Universe where furious firestorms of starbirth blazed across the skies. The spectacular cluster?s opulence is dimmed when seen from Earth only by the fact that it is 12 000 million light years away.

The discovery of this unique and tantalising object was the result of a systematic study of distant clusters of galaxies carried out with major X-ray, optical and infrared telescopes, including the NASA/ESA Hubble Space Telescope, ROSAT and the Keck Telescopes. Bob Fosbury, of the European Space Agency?s Space Telescope-European Coordinating Facility in Germany, and a team of international co-authors report the discovery in the 20 October 2003 issue of the Astrophysical Journal.

The mega-cluster of stars appears as a puzzling red arc behind a distant galaxy cluster 5400 million light-years away in the northern constellation of Lynx. The arc is the stretched and magnified image of a mysterious celestial object about 12 000 million light-years away (at a redshift of 3.36), far beyond the cluster of galaxies. This means that the remote source existed when the Universe was less than 2000 million years old.

Fosbury and colleagues first tried to identify the arc by analysing the light from the object, but the team was not able to recognise the pattern of colours in the spectral signature of the remote object. While looking for matches with the colour spectrum, Fosbury realised that the light was related to that of the nearby Orion Nebula, a star-forming region in our own Milky Way. However where the Orion Nebula is powered by only four hot and bright blue stars, the Lynx Arc must contain around a million such stars!

Furthermore, the spectrum shows that the stars in the Lynx Arc are more than twice as hot as the Orion Nebula?s central stars, with surface temperatures up to 80 000?C. Though there are much bigger and brighter star-forming regions than the Orion Nebula in our local Universe, none are as bright as the Lynx Arc, nor do they contain such large numbers of hot stars.

Even the most massive, normal nearby stars are no hotter than around 40 000?C. However, stars forming from the original, pristine gas in the early Universe can be more massive and consequently much hotter – perhaps up to 120 000?C. The earliest stars may have been as much as several hundred solar masses, but the chemical make-up of the Universe today prevents stars from forming beyond about 100 solar masses. Such ?primordial? super-hot stars are thought to be the first luminous objects to condense after the Big Bang cooled. Astronomers believe that these first ?monster? stars formed considerably earlier than the Lynx Arc ? up to 1800 million years earlier. ?This remarkable object is the closest we have come so far to seeing what such primordial objects might look like when our telescopes become powerful enough to see them,? says Fosbury. The desire to find and study the first luminous objects in the Universe is the main scientific drive behind the construction of the NASA/ESA/CSA James Webb Space Telescope, scheduled for launch in 2011.

Original Source: ESA News Release

Image credit: Hubble

The newest image from the Hubble Space Telescope is of the Sombrero Galaxy, which was pieced together from a mosaic of six images taken by Hubble’s Advanced Camera for Surveys. The Sombrero Galaxy is quite large; visually it’s one-fifth the size of the Moon in a telescope. This release marks the fifth anniversary of the Hubble Heritage Project, which uses telescope time to release beautiful astronomy images to the public.

The Hubble Heritage Team of astronomers, who assemble many of the NASA Hubble Space Telescope’s most stunning pictures, is celebrating its five-year anniversary with the release of the picturesque Sombrero galaxy. One of the largest Hubble mosaics ever assembled, this magnificent galaxy is nearly one-fifth the diameter of the full moon. The team used Hubble’s Advanced Camera for Surveys to take six pictures of the galaxy and then stitched them together to create the final composite image. The photo reveals a myriad of stars in a pancake-shaped disk as well as a glowing central bulge of stars.

Since its inception in 1998, the Hubble Heritage Project has released more than 65 images of dazzling celestial objects, including planets, dying stars, regions of star formation, clusters of stars, individual galaxies, and even clusters of galaxies. This has been done on a monthly basis.

The Heritage team of Space Telescope Science Institute astronomers and image processing specialists selects images from the Hubble Space Telescope’s public data archive. This database contains approximately 500,000 raw images taken over the past 13 years. Although astronomers use Hubble to photograph numerous celestial objects, those results are usually shared with only the astronomical community. The Heritage team periodically combs the archive looking for interesting, but unreleased, pictures to become Heritage image candidates.

“Some of the photogenic objects that have been scientific targets often lack sufficient exposure across a range of colors,” explains Keith Noll, the Heritage lead scientist. “In other archival images the telescope’s field of view only covers a small, unrecognizable portion of the object, so we have to fill in the rest.”

The Hubble Heritage Project has been granted a small amount of observing time to essentially “fill in the gaps” in these images. The Heritage astronomers also seek visually interesting objects in the universe that have not yet been selected for Hubble scientific observations. For the Sombrero galaxy, the Heritage program devoted a number of orbits to complete a photo mosaic of the object.

Public visitors to the Heritage website (http://heritage.stsci.edu) have also been invited to help select attractive astronomical targets. One overwhelming choice of the voters was the famous Horsehead Nebula in the constellation Orion the hunter.

The Heritage program has been recognized for its contribution to inspiring the public with some of the most photogenic images ever produced in astronomy. Recent achievements for the team include the Astronomical Society of the Pacific 2003 Klumpke-Roberts award for “outstanding contributions to the public understanding and appreciation of astronomy.” In 2002, two Heritage images were selected in the Rochester Institute of Technology’s “Images From Science” traveling gallery exhibit. Several images have been selected by the US and UK postal systems. In 2000, a first-class US postage stamp showing the Ring Nebula was one of five Hubble images selected to be part of a commemorative series of stamps honoring astronomer Edwin P. Hubble.

Hubble’s new Advanced Camera for Surveys, and eventually the planned Wide Field Camera 3, promise to give the Heritage team an opportunity to share with the public even more opulent views of our colorful universe.

Original Source: Hubble News Release

Image credit: Hubble

Astronomers from the European Space Agency are tracking hundreds of galaxies with the Hubble Space Telescope, hoping that one or more stars will eventually explode as a supernova. They can then look back through the data and find the individual star that exploded – this would mean it was in the final stages of its life. So far, supernova have only been tracked back to two “mother stars” so far, so astronomers really need more of this data to help understand the conditions that cause a star to go supernova.

A team of European astronomers is using the NASA/ESA Hubble Space Telescope to look back in time. They have imaged the spiral galaxy NGC 3982 and hundreds of other galaxies in the hope that one of the millions of stars in these images will some day explode as a supernova. They can then look back and pinpoint the exact star that has exploded. Only two such supernova ‘mother stars’ have ever been identified.

The fantastic resolution of the Hubble Space Telescope allows individual massive stars in other galaxies to be detected. A team from Cambridge and Trieste have used Hubble and ESO?s Very Large Telescope to image NGC 3982 and several hundred other nearby galaxies in the hope that a few of the stars in these images will explode as supernovae in the future.

When a star of more than 10 times the mass of our Sun reaches the end of its nuclear fuel reserve, it can no longer produce enough energy to keep it from collapsing under its own immense weight. The core of the star collapses, and the outer layers are ejected in a fast-moving shock wave. These supernova explosions are at the heart of our understanding of the evolution of galaxies and the formation of the chemical elements in the Universe. Yet astronomers have been able to identify only two stars that later exploded as supernovae with any confidence.

Supernovae have many different characteristics and understanding exactly which type of star produces which kind of supernova is a fundamental challenge. To find these supernova ‘mother stars’, the team has undertaken this intensive study of the nearby Universe and is now playing a waiting game.

It appears that typical spiral galaxies produce one supernova roughly every 100 years and so the team has to study a large number of galaxies to stand a chance of being lucky enough to catch a star before it destroys itself and becomes either a neutron star or a black hole.

By using the most powerful telescopes both in space and on the ground to take images at different optical and infrared wavelengths, the temperature, luminosity, radius and mass of the stars that later explode can be estimated. This will allow astronomers to see exactly which types of stars produce supernovae and to test if their theories for the origins of these cosmic explosions are correct.

The beautiful galaxy NGC 3982 is a typical spiral galaxy and looks just as our own galaxy, the Milky Way, would if we could view it face on. It harbours a huge black hole at its core and has massive regions of star formation in the bright blue knots in the spiral arms. Supernovae are most likely to be found within these energetic regions.

Original Source: ESA News Release

Image credit: ESA

The Hubble Space Telescope has been making detailed observations of Comet 67P/Churyumov-Gerasimenko – the new target for the European Space Agency’s Rosetta mission. The data from Hubble has helped the ESA make precise measurements of the comet’s shape, size and spin-rate so they can fine-tune Rosetta’s flight. If all goes well, Rosetta will launch on February 26, 2004, and then take 10 years to reach the comet. It will orbit the comet and then drop a scientific package onto the surface which should provide scientists with plenty of new data.

Results from the NASA/ESA Hubble Space Telescope have played a major role in preparing ESA?s ambitious Rosetta mission for its new target, comet 67P/Churyumov-Gerasimenko.

Hubble has been used to make precise measurements of the size, shape and rotational period of the comet. Information that is essential if Rosetta is to rendezvous with the comet and then drop down a probe, something never before attempted and yet a major step towards elucidating the origins of the solar system.

Observations made by Hubble in March this year revealed that comet 67P/Churyumov-Gerasimenko (67P/C-G) is approximately five by three kilometres in size and shaped like a rugby ball. ESA mission scientists were concerned about the exact size of the solid nucleus, which is needed to adapt the mission to the comet?s gravity.

“Although 67P/C-G is roughly three times larger than the original Rosetta target, its highly elongated shape should make landing on its nucleus feasible, now that measures are in place to adapt the lander package to the new scenario,” says Dr Philippe Lamy of the Laboratoire d’Astronomie Spatiale in France, who is presenting the Hubble results on comet 67P/C-G today at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society in California, USA.

Mission scientists began looking for an alternative target when the Rosetta mission’s launch date was postponed. The delay meant that the original target comet, 46P/Wirtanen, was no longer easily reachable. But scientists did not have enough information on the back-up comet, 67P/C-G, and sought data from the largest telescopes.

Using a technique developed over the past decade by Philippe Lamy, Imre Toth (Konkoly Observatory, Hungary), and Harold Weaver (Johns Hopkins University Applied Physics Laboratory, Laurel, USA), the team snapped 61 Hubble images of comet 67P/C-G over a period of 21 hours on 11 and 12 March. Hubble’s Wide Field Planetary Camera 2 isolated the comet’s nucleus from the coma, the diffuse gas surrounding the nucleus, quickly providing the figures required. The telescope showed that the nucleus is ellipsoidal and measured its rotation rate at approximately 12 hours.

Rosetta’s launch is currently planned for February 2004, with a rendezvous with the comet about 10 years later.

Original Source: ESA News Release