Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

June 12, 1996

Vela Supernova Remnant in X-ray

Explanation: What happens when a star explodes? A huge fireball of hot gas shoots out in all directions. When this gas slams into the existing interstellar medium, it heats up so much it glows in X-rays. The above picture by the ROSAT satellite has captured some of these X-rays and shown -- for the first time -- the Vela supernova explosion was roughly spherical. Non-uniformity of the interstellar medium causes Vela's appearance to be irregular. The size of this X-ray emitting spherical shell is immense - 230 light years across, covering over 100 times the sky-area of the full Moon. The supernova that created this nebula occurred about 1500 light years away and about 11,000 years ago. Coincidently, a completely different supernova shell can also be seen in X-rays in this picture! It is visible as the bright patch near the upper right. This Puppis supernova remnant nebula is actually about four times farther than the Vela nebula.

Tomorrow's picture: Vela Supernova Remnant in Optical

| Archive | Index | Search | Glossary | Education | About APOD |

Authors & editors: Robert Nemiroff (GMU) & Jerry Bonnell (USRA).
NASA Technical Rep.: Sherri Calvo. Specific rights apply.
A service of: LHEA at NASA/ GSFC