Jennifer Francis, of Christ the King School, asks :-

What is a star?

Karen Pollard, an astronomer at the University of Canterbury, responded.

A star is a huge ball of burning gas.

Most stars are so far away that, when we look at them at night, they look just like points of light. The nearest star to the Earth is our own Sun and, because it is so close, it looks bigger than the other stars. However, the Sun is a very ordinary star.

The insides of stars are extremely hot. The temperature at the centre of our Sun is about 10 million degrees. The surface of the Sun is much cooler, but is still about 6000 degrees! Most stars are made up mainly of hydrogen gas. As the hydrogen gas burns, the stars radiate heat and light. This process of burning hydrogen is called "thermonuclear fusion."

Planets are small bodies that orbit around stars. Our solar system has nine planets that orbit around the Sun. Planets are much smaller than stars. Even the giant gas planet, Jupiter, in our solar system is much smaller than the Sun. You could fit about 1000 Jupiters inside the Sun.

When you look up at the night sky, it is often difficult to tell the difference between stars and planets. They both appear like points of light. However, if you look at a planet through a small telescope or binoculars, it appears as a disk, whereas a star still looks like a point of light. This is because the planets in our solar system are much closer to the Earth than the stars we see in the night sky. The planets shine because they reflect the light from the Sun. They do not produce their own light like stars do.