Stars are massive balls of gas that produce heat and light. The Sun is the nearest star to Earth, but it is just one of billions of stars in the Milky Way galaxy, and the Milky Way is one of billions of galaxies in the universe. Although stars are many many times larger than Earth, and often much larger than the Sun, they appear as small dots of light in the sky because they are so far away. Stars can be different sizes and different colours which tells us a lot about their age and temperature. Although stars are so far away, astronomers have managed to find planets in orbit of some them!