The air up in the exosphere is super thin and gradually decreases as you go higher in altitude. Air is so thin in this region that it might as well be airless. The exobase is the bottom layer of the exosphere, when sunspots are more active then the exobase will rise in altitude whereas if there is low activity of sunspots then then the altitude will drop. Altitude of the exobase can range from 500-1000km. Scientist argue whether the exosphere is a part of our atmosphere at all. Some think that this is just another part of outer space, while others think that it is a part of our atmosphere. There is no actual evidence that shows that exosphere just stops but it gradually decreases. Estimates are saying that the exosphere stops at about 190,000km away from Earth's surface. The highest layer of the exosphere is called the geocorona, a section filled with UV glow. This section of the exoshpere is where satellites appear. Earth's atmosphere is supposed to gradually stop halfway between the surface of the Earth and moon. Many scientist would consider the exosphere to be a part of the atmosphere due to the drag force. There is still enough drag force to pull a satellite down to Earth.