supernova remnant SNR0103-72.6
Supernova remnant SNR0103-72.6

A supernova (also called a supernovae) is an exploding star. As you can imagine, stellar explosions produce a huge amount of energy.

Astronomers categorize supernovas into two types:

  • Type Ia
  • Type II

Type Ia supernovas occur in binary star systems, where two stars are relatively close together. Typically, one of the stars in the binary system has become a white dwarf. What happens to cause the supernova is that gas from one star reaches the white dwarf and this causes the white dwarf to explode. Type Ia supernovas are typically brighter than Type II supernovas.

Because Type Ia supernovas always occur in the same way and because the light they produce is always about the same, astronomers can determine how far away they are from Earth by their luminescence. Astronomers use this information to determine how fast the universe is expanding (Maran, 2005).

Type II supernovas occur when a star much more massive than our Sun explodes. A star that is destined to become a supernova is called a progenitor. The supernova explosion occurs at the end of the star's life cycle. After a massive star explodes or goes supernova, it leaves behind a neutron star or implodes in on itself and forms a black hole.

Because light takes so long to reach us, the supernovas that we observe happened a long time ago. For example, the Chandra X-Ray Observatory image of supernova remnant SNR0103-72.6 is from an exploding star located in the Small Magenellanic Cloud, which is about 190,000 light-years from Earth. The supernova explosion occurred about 200,000 Earth years ago.

In another example, the image below shows a supernova explosion (Supernova 1987A) that occurred in the Large Magellanic Cloud in 165,000 BC, but its light didn't reach Earth until 1987.

supernova in large magellanic cloud

For years, scientists have believed that supernovas may provide the elements and molecules that are necessary for supporting life in the universe, such as oxygen, helium, hydrogen, and others.

The Chandra x-ray image of the supernova above, as well as other images taken by NASA, have shown the presence of oxygen, other gases, and molecules in the outer rings of supernovas, thereby confirming scientists' hypotheses.

These elements and molecules are created within the star by nuclear reactions and when the star explodes these elements are flung into space. These elements and molecules are then dispersed throughout space to form new planets or stars (Moche, 2004).


Maran, S. P. (2005). Astronomy for Dummies. Wiley: Indianapolis, IN.

Moche, D. L. (2004). Astronomy. Wiley: Hoboken, NJ.

Image of supernova remnant SNR0103-72.6: Courtesy of NASA Marshall Space Flight Center (NASA-MSFC).
Image of supernova 1987A: Courtesy of NASA Goddard Space Flight Center (NASA-GSFC).