A supernova is a stellar explosion triggered by a sudden reignition of nuclear fusion in a degenerate star or by the collapse of the core of a massive star.

Astronomers discover supernovae typically by looking at some of the closer galaxies through an optical telescope and comparing them to earlier photographs.

Image Credit: European Southern Observatory

Amateur astronomers, who greatly outnumber professional astronomers, have played an important role in finding supernovae.

In the 1960s, astronomers found that the maximum intensities of supernova explosions could be used as standard candles, hence indicators of astronomical distances. Most scientific interest in supernovae is using it as standard candles for measuring distance.

Credits for X-ray Image: NASA/CXC/ASU/J. Hester et al.
Credits for Optical Image: NASA/HST/ASU/J. Hester et al.

Some of the most distant supernovae recently observed appeared dimmer than expected. This supports the view that the expansion of the universe is accelerating.

Supernova may help determine answers to those really big questions that begged by theoretical and observational cosmology.

Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: Y.-H. Chu (UIUC), S. Kulkarni (Caltech), and R. Rothschild (UCSD)

Where is the missing mass in the universe? Is the inflation hypothesis for the beginning of the universe correct? Is there a repulsive component to gravity? Why and how precisely is our part of the universe moving towards the Great Attractor?

Image Credit: ESO/M. Kornmesser / CC BY 3.0