When galaxies collide — a common event in the …

When galaxies collide — a common event in the
universe — a fresh burst of star formation typically takes place as gas clouds
mash together. At this point, the galaxy has a blue hue, but the color does not
mean it is cold: it is a result of the intense heat of newly formed blue–white
stars. Those stars do not last long, and after a few billion years the reddish
hues of aging, smaller stars dominate an elliptical galaxy’s spectrum. 

Our Hubble Space Telescope (@NASAHubble) caught
sight of a soft, diffuse-looking galaxy, perhaps the aftermath of a long-ago
galactic collision when two spiral galaxies, each perhaps much like the Milky
Way, swirled together for millions of years.

In such mergers, the original galaxies are often
stretched and pulled apart as they wrap around a common center of gravity.
After a few back-and-forths, this starry tempest settles down into a new, round
object. The now subdued celestial body is technically known as an elliptical

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Credit: ESA/Hubble & NASA