How do the sizes of stars vary across the universe?

Stars across the universe vary greatly in size, from small neutron stars to supergiant stars.

Stars are categorised into different types based on their size, temperature, and brightness. The smallest stars, known as neutron stars, are incredibly dense and have a radius of only about 10 kilometres. Despite their small size, they have a mass comparable to that of our Sun. Neutron stars are the remnants of supernova explosions, where the core of a massive star collapses under its own gravity.

On the other end of the scale, we have supergiant stars. These are the largest stars in the universe, with diameters that can be hundreds or even thousands of times larger than our Sun. Betelgeuse, a red supergiant star in the constellation of Orion, is one such example. If placed at the centre of our solar system, its surface would extend past the orbit of Jupiter.

In between these extremes, we have stars like our Sun, which is classified as a yellow dwarf. It has a diameter of about 1.4 million kilometres, which is considered average in size. There are also white dwarfs, which are roughly the size of Earth but much denser, and red dwarfs, which are smaller and cooler than our Sun.

The size of a star is determined by its mass and the stage of its life cycle. Stars begin their lives as clouds of gas and dust, collapsing under their own gravity to form protostars. As they continue to accumulate mass, they become main sequence stars like our Sun. When they exhaust their nuclear fuel, they expand into red giants or supergiants, before ending their lives as white dwarfs, neutron stars, or black holes.

In conclusion, the universe is home to a vast array of stars, each with its own unique size and characteristics. From tiny, dense neutron stars to colossal supergiants, the size of stars is as diverse as the universe itself.