A star's life begins as a nebula, a vast cloud of gas and dust.

When a nebula collapses under its own gravity, it forms a protostar, which eventually becomes a star.

Stars generate energy through nuclear fusion reactions in their cores, where hydrogen atoms are fused into helium atoms.

The color of a star is determined by its surface temperature, with hotter stars appearing blue or white and cooler stars appearing red or orange.

When a star runs out of hydrogen fuel in its core, it expands and becomes a red giant.

For stars with masses similar to our Sun, the final stage of their life cycle is to become a white dwarf, a dense remnant of the star's core.

After a massive star explodes in a supernova, it can leave behind a black hole or a neutron star, depending on the mass of the star's core.

Stars with masses several times that of our Sun will eventually explode in a supernova.

The expanding shell of gas and dust that is ejected during a supernova is called a supernova remnant.

The collapse of a massive star's core after a supernova can result in the formation of a black hole or a neutron star, depending on the mass of the core.

Stars gradually lose mass through their stellar wind, a process known as mass ejection.

Red dwarf stars have the longest lifespans among all types of stars.

The Hertzsprung-Russell diagram shows the relationship between a star's mass and its luminosity.

The Big Crunch is the hypothetical point in the future when the universe will reach its maximum expansion and begin to contract.

A supernova is the process by which a star's core collapses and releases a burst of energy, causing the star to explode.