Black Holes

Black holes The gravity on neutron stars, white dwarfs and black dwarfs is so strong that it crushes atoms, so the matter in stars is millions of times denser than anything on earth. A black hole is formed if enough of this dense matter is left behind after a supernova explosion then the gravitational field is so strong that nothing can escape not even light. Scientists know they exist using x-rays

Black Holes

The intense gravitational field left when a giant star collapses

Satellites Path followed by satellite Path followed if gravity switched off Pull of gravity Earth

Useful orbits There are TWO main orbits that are useful called POLAR and EQUATORIAL. POLAR -The orbit is close to the Earth, only just above the atmosphere. With a good camera you can see the headlines on a newspaper!

Because the Earth spins the satellite will ‘see’ every part of the Earth once every 24 hours. This orbit is used for spy and weather satellites. Polar orbits

Equatorial orbits At the right distance the satellite will take 24 hours to orbit the Earth. Because the Earth is also spinning once each 24 hours the satellite stays above the same place on the Earth all the time. We call this a GEOSTATIONARY orbit. This orbit is used for communication satellites, like Sky TV.