The exosphere is the outer boundary of our atmosphere (outside the thermosphere). It reaches to about 6,200 miles (1,000 km) above the Earth. This is the level of the atmosphere where our satellites orbit the earth. There are more than 3,000 satellites orbiting the Earth in the exosphere. Only about one third of them are still working. Scientists believe there are at least 10,000 more bits of junk and debris in orbit with the satellites. That’s a lot of junk in space!