Abell 1689 is a massive cluster of galaxies located about 2.3 billion light-years away.

In 1995 or 1996 a supernova exploded in a nearby galaxy, but no one on Earth knew it at the time.

RCW 108 is a region where stars are actively forming about 4,000 light-years from Earth.

The giant galaxy, Perseus A, which is also known as NGC 1275, is a well-known source of strong radio radiation.

The giant galaxy, Perseus A, which is also known as NGC 1275, is a well-known source of strong radio radiation.

This composite of data from NASA's Chandra X-ray Observatory and the Hubble Space Telescope is another look for NGC 6543, better known as the Cat's Eye nebula.

This composite of data from NASA's Chandra X-ray Observatory and the Hubble Space Telescope is another look for NGC 6543, better known as the Cat's Eye nebula.

Two galaxy clusters, each a quadrillion times the mass of the Sun, collided to form the system formally known as Macs J0025.4-1222.

Two galaxy clusters, each a quadrillion times the mass of the Sun, collided to form the system formally known as Macs J0025.4-1222.

This image of the mammoth spiral galaxy M81, located about 12 million light years away, contains data from four different NASA satellites.

The brightest supernova ever recorded on Earth, this spectacular light show was documented in China, Japan, Europe, and the Arab world. It was brighter than Venus, and visible during the day for weeks.