Bright stars are stars that appear to be particularly luminous in the night sky. The term 'bright stars' can refer to two different types of stars: novas and novae. Novas are stars that suddenly increase in brightness, while novae are stars that undergo a sudden, dramatic increase in brightness and then slowly fade away. Both novas and novae are caused by nuclear reactions in the star's core, and they can be seen from Earth with the naked eye.