This artist's concept illustrates one of the largest smash-ups of galaxies
ever observed. NASA's Spitzer Space Telescope spotted the four galaxies
shown here (yellow blobs) in the process of tangling and ultimately
merging into a single gargantuan galaxy. Though the galaxies appear to be
fairly intact, gravitational disturbances have caused them to distort and
twist, flinging stars (white dots) everywhere like sand. Other nearby
galaxies can be seen as small, bluish blobs.
The so-called "quadruple merger" is the largest known merger between
galaxies of a similar size. While three of galaxies are about the size of
our Milky Way, the fourth (center of image) is three times as big. All
four of the galaxies are blob-shaped ellipticals instead of spirals like
the Milky Way.
The plume shown emanating from the biggest galaxy contains billions of
stray stars -- almost three times as many as are in the Milky Way --
kicked out during the merger. About half of the stars in the plume will
fall back and join the new galaxy, making it one of the biggest galaxies
in the universe.
The quadruple merger is part of a giant galaxy cluster, called CL0958+4702,
located nearly five billion light-years away.
