Supernova
From Simple English Wikipedia, the free encyclopedia
A supernova is when a very big star explodes. This happens when a star totally runs out of energy to fuse. Only stars that were giants all of their lives explode. Then they become a black hole or a neutron star. Small stars do not explode. They cool and shrink down into a white dwarf.
Supernovas are very big explosions. When the star explodes, it will be brighter than all other stars. If a supernova explosion happened near the Earth, we could see it in the sky even during the day.
Supernova explosions happen rarely. In our own galaxy, the Milky Way, the last supernova happened in the year 1604. We can see supernovas in other galaxies too. Every year we see 300 supernovas in other galaxies, because there are so many galaxies.
[edit] Supernovas and life
Without supernovas there would be no life on Earth. This is because many of the chemical elements were made in supernova explosions. These are called "heavy elements". Heavy elements are needed to make living things. The supernova is the only way heavy elements can be made. Other elements were made by fusion in stars. Heavy elements need very high temperature and pressure to form. In a supernova explosion the temperature and pressure are so high that heavy elements can be made. Scientists call this supernova nucleosynthesis.
It could be dangerous if a supernova explosion happened very close to the Earth. The explosion is very big and many kinds of dangerous radiation are formed. But we do not have to be afraid. Only very big stars can explode as supernovas. There are no stars big enough near the Earth.
[edit] Supernovas and science
Scientists can learn things from supernova explosions. Astronomers and scientists who study cosmology often look at supernovas.
