This Hubble picture shows the streaks characteristic of gravitational lensing.
NASA caption
Scanning the heavens for the first time since the successful December
1999 servicing mission, NASA's Hubble Space Telescope imaged a
giant, cosmic magnifying glass, a massive cluster of galaxies called
Abell 2218. This 'hefty' cluster resides in the constellation Draco,
some 2 billion light-years from Earth. The cluster is so massive that
its enormous gravitational field deflects light rays passing through
it, much as an optical lens bends light to form an image. This
phenomenon, called gravitational lensing, magnifies, brightens, and
distorts images from faraway objects. The cluster's magnifying powers
provides a powerful "zoom lens" for viewing distant galaxies that could
not normally be observed with the largest telescopes.
The picture is dominated by spiral and elliptical galaxies. Resembling
a string of tree lights, the biggest and brightest galaxies are members
of the foreground cluster. Researchers are intrigued by a tiny red dot
just left of top center. This dot may be an extremely remote object
made visible by the cluster's magnifying powers. Further investigation
is needed to confirm the object's identity.
The color picture already reveals several arc-shaped features that are
embedded in the cluster and cannot be easily seen in the black-and-
white image. The colors in this picture yield clues to the ages,
distances, and temperatures of stars, the stuff of galaxies. Blue
pinpoints hot young stars. The yellow-white color of several of the
galaxies represents the combined light of many stars. Red identifies
cool stars, old stars, and the glow of stars in distant galaxies. This
view is only possible by combining Hubble's unique image quality with
the rare lensing effect provided by the magnifying cluster.
Picture and accompanying explanation courtesy of NASA. More pictures at NASA Image eXchange
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