This image shows a peculiar galaxy what looks like a cart, or wagon, wheel. It is the result of a rare and spectacular head on collision between this galaxy and possible one of the other two that you see at the right. The Cartwheel galaxy was probably shaped like a spiral (like our own Milky Way) before the collision but, like a stone tossed into a pond, the collision sent out a ripple of energy that compressed the galaxy's gas in its wake and distorted its shape. This circular ripple of compressed gas is currently at the position of the Cratwheel's "rim" and has resulted in a burst of star formation that causes the rim to shine brightly.