Galaxy Cluster Abell 370 and Asteroids

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As if this Hubble Space Telescope picture isn't cluttered enough with myriad galaxies, nearby asteroids photobomb the image, their trails sometimes mimicking background astronomical phenomena.

The stunningly beautiful galaxy cluster Abell 370 contains an astounding assortment of several hundred galaxies tied together by the mutual pull of gravity. Located approximately 4 billion light-years away in the constellation Cetus, the Sea Monster, this immense cluster is a rich mix of a variety of galaxy shapes.

Entangled among the galaxies are thin, white trails that look like curved or S-shaped streaks. These are trails from asteroids that reside, on average, only about 260 million kilometers from Earth – right around the corner in astronomical terms. The trails appear in multiple Hubble exposures that have been combined into one image. Of the 22 total asteroid sightings for this field, five are unique objects. These asteroids are so faint that they were not previously identified.

The asteroid trails look curved due to an observational effect called parallax. As Hubble orbits around Earth, an asteroid will appear to move along an arc with respect to the vastly more distant background stars and galaxies. The motion of Earth around the Sun, and the motion of the asteroids along their orbits, are other contributing factors to the apparent skewing of asteroid paths.

All the asteroids were found manually, the majority by "blinking" consecutive exposures to capture apparent asteroid motion. Astronomers found a unique asteroid for every 10 to 20 hours of exposure time. These asteroid trails should not be confused with the mysterious-looking arcs of blue light that are actually distorted images of distant galaxies behind the cluster. Many of these far-flung galaxies are too faint for Hubble to see directly. Instead, in a dramatic example of "gravitational lensing", the cluster functions as a natural telescope, warping space and affecting light traveling through the cluster toward Earth.

The Frontier Fields program is a collaboration among several space telescopes and ground-based observatories to study six massive galaxy clusters and their effects. Using a different camera, pointing in a slightly different direction, Hubble photographed six so-called "parallel fields" at the same time it photographed the massive galaxy clusters. This maximised Hubble's observational efficiency in doing deep space exposures. These parallel fields are similar in depth to the famous Hubble Deep Field, and include galaxies about four-billion times fainter than can be seen by the human eye.

This image was assembled from several exposures taken in visible and infrared light. The field's position on the sky is near the ecliptic, the plane of our Solar System. This is the zone in which most asteroids reside, which is why Hubble astronomers saw so many crossings. Hubble deep-sky observations taken along a line-of-sight near the plane of our Solar System commonly record asteroid trails.

Image Credit: NASA, ESA, and B. Sunnquist and J. Mack (STScI)

Acknowledgment: NASA, ESA, and J. Lotz (STScI) and the HFF Team

Image enhancement: Jean-Baptiste Faure

Asteroid Vesta full-frame image taken by Dawn spacecraft!

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NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011. It was taken from a distance of about 5,200 kilometers (3,200 miles). Dawn entered orbit around Vesta on July 15, and will spend a year orbiting the body. After that, the next stop on its itinerary will be an encounter with the dwarf planet Ceres. The framing camera project is funded by NASA, the Max Planck Society and DLR.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Close-up view of "Snowman" Craters on Asteroid Vesta

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In this image, obtained by the framing camera on NASA's Dawn spacecraft, a set of three craters, informally nicknamed "Snowman" by the camera's team members, is located in the northern hemisphere of Vesta. The image was taken on July 24, 2011, from a distance of about 5,200 kilometers (3,200 miles). The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate, Washington, D.C. It is a project of the Discovery Program, managed by NASA's Marshall Space Flight Center, Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corporation of Dulles, Va., designed and built the Dawn spacecraft.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Stunning color image of Asteroids Ida and Dactyl

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This color picture is made from images taken by the imaging system on the Galileo spacecraft about 14 minutes before its closest approach to asteroid 243 Ida on August 28, 1993. The range from the spacecraft was about 10,500 kilometers (6,500 miles). The images used are from the sequence in which Ida's moon was originally discovered; the moon is visible to the right of the asteroid. This picture is made from images through the 4100-angstrom (violet), 7560 A (infrared) and 9680 A (infrared) filters. The color is 'enhanced' in the sense that the CCD camera is sensitive to near infrared wavelengths of light beyond human vision; a 'natural' color picture of this asteroid would appear mostly gray. Shadings in the image indicate changes in illumination angle on the many steep slopes of this irregular body as well as subtle color variations due to differences in the physical state and composition of the soil (regolith). There are brighter areas, appearing bluish in the picture, around craters on the upper left end of Ida, around the small bright crater near the center of the asteroid, and near the upper right-hand edge (the limb). This is a combination of more reflected blue light and greater absorption of near infrared light, suggesting a difference in the abundance or composition of iron-bearing minerals in these areas. Ida's moon also has a deeper near-infrared absorption and a different color in the violet than any area on this side of Ida. The moon is not identical in spectral properties to any area of Ida in view here, though its overall similarity in reflectance and general spectral type suggests that it is made of the same rock types basically. These data, combined with study of further imaging data and more detailed spectra from the Near Infrared Mapping Spectrometer, may allow scientists to determine whether the larger parent body of which Ida, its moon, and some other asteroids are fragments was a heated, differentiated object or made of relatively unaltered primitive chondritic material. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory.
Credit: NASA/JPL

A view of the Asteroid Lutetia from the ESA Rosetta probe

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This image of the unusual asteroid Lutetia was taken by ESA's Rosetta probe during its closest approach in July 2010. Lutetia, which is about 100 kilometres across, seems to be a leftover fragment of the same original material that formed the Earth, Venus and Mercury. It is now part of the main asteroid belt, between the orbits of Mars and Jupiter, but its composition suggests that it was originally much closer to the Sun.
Credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

NASA's Dawn Spacecraft views dark side of Asteroid Vesta

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NASA's Dawn spacecraft took this image over Vesta's northern hemisphere after the spacecraft completed its first passage over the dark side of the giant asteroid. It is northern hemisphere winter on Vesta now, so its north pole is in deep shadow. The Dawn science team is working to determine the significance of the distinct features in this image, which include large grooves or ridges extending for great distances around Vesta. This image was taken by Dawn's framing camera on July 23, from a distance of 3,200 miles (5,200 kilometers).The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA. The University of California, Los Angeles, is responsible for overall Dawn mission science. The Dawn framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by DLR German Aerospace Center, Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The Framing Camera project is funded by the Max Planck Society, DLR, and NASA/JPL.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Asteroid Eros as seen by the orbiting NASA's NEAR spacecraft!

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This picture of Eros, the first of an asteroid taken from an orbiting spacecraft, is a mosaic of four images obtained by NASA's NEAR mission immediately after the spacecraft's insertion into orbit. We are looking down over the north pole of Eros at one of the largest craters on the surface, which measures 4 miles (6 kilometers) across.
Inside the crater walls are subtle variations in brightness that hint at some layering of the rock in which the crater formed. Narrow grooves that run parallel to the long axis of Eros cut through the southeastern part of the crater rim. A house-sized boulder is present near the floor of the crater; it appears to have rolled down the bowl-shaped crater wall. A large number of boulders are also present on other parts of the asteroid's surface. The surface of the asteroid is heavily cratered, indicating that Eros is relatively old.
Credit: NASA/JPL/JHUAPL