A Strange Ring Galaxy: On the outside is a ring dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older. Between the two is a gap that appears almost completely dark. How Hoag's Object formed remains unknown, although similar objects have been identified & collectively labeled as a form of ring galaxy. Genesis. Hypotheses include a galaxy collision billions of years ago & the gravitational effect of a central bar that has since vanished
The “Black Widow” pulsar is moving through the galaxy at a speed of almost a million kilometers per hour. A bow shock wave due to this motion is visible to optical telescopes, shown in this image as the greenish crescent shape. The pressure behind the bow shock creates a second shock wave that sweeps the cloud of high-energy particles back from the pulsar to form the cocoon.
The beautiful Trifid Nebula is a cosmic study in colorful contrasts. Also known as M20, it lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star forming region in the plane of our galaxy, the Trifid Nebula is about 40 light-years across.
NGC 474 is an elliptical galaxy in the constellation Pisces. This large galaxy is known to possess tidal tails, although their origins remain unknown. These tidal tails may be related to debris left over from absorbing numerous small galaxies in the past billion years. Or the shells may be like ripples in a pond, where the ongoing collision with the spiral galaxy just above NGC 474 is causing density waves to ripple though it.