Solar Physics

Find out about the different elements of space weather and how space weather affects the Earth.

Imagine a star so big that if it replaced the Sun, it could engulf the Solar System as far out as the orbit of Saturn. Or one that produces as much energy in one second as our Sun does in a hundred days. These are hypergiant stars.

For the last four hundred years, the only supernovae we've seen have been in other galaxies. When is the Milky Way due its next supernova?

The Chandrasekhar limit is an upper bound on the mass of bodies made from electron-degenerate matter, a dense form of matter which consists of nuclei immersed in a gas of electrons.

Electron degeneracy pressure is a consequence of the Pauli exclusion principle, which states that two fermions cannot occupy the same quantum state at the same time. The force provided by this pressure sets a limit on the extent to which matter can be squeezed together without it collapsing into a neutron star or black hole.

The Hertzsprung-Russell diagram shows the relationship between different properties of stars and illustrates trends among stars. The diagram was created in 1910 by Ejnar Hertzsprung and Henry Norris Russell, and represented a huge leap forward in understanding stellar evolution, or the 'lives of stars'.

We are all pretty familiar with stars. We see them on clear nights as tiny, twinkling pinpricks of light in the sky. They have intrigued mankind since the beginning of time, but what is a star?

In astronomy, spectral classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics and subsequently refined in terms of other characteristics.

In astronomy, luminosity is the total amount of energy radiated by a star, galaxy, or another astronomical object per unit time. It is related to the brightness, which is the luminosity of an object in a given spectral region. In SI units luminosity is measured in joules per second or watts.