Kuwait discusses steps to lower emissions as temperatures rise - in pictures

1. Black holes are objects whose gravity is so strong not even light can escape their pull

2. They can be created when massive stars collapse under their own weight

3. Large black holes can also be formed when smaller ones collide and merge

4. The biggest black holes lurk at the centre of many galaxies, including our own

5. Astronomers believe that when the universe was very young, black holes affected how galaxies formed