Airplanes typically operate at altitudes of up to 12,000 meters (39,000 feet), in the lower levels of the atmosphere known as the troposphere and stratosphere. Satellites mostly orbit within the troposphere, stratosphere, and the outermost layer, the thermosphere.
The thermosphere is a region at very high altitudes, starting at about 90 kilometers (55 miles) above the Earth's surface. At such high altitudes, the air is extremely thin and rarefied, making it unsuitable for airplanes to generate enough lift for sustained flight. There is not enough air density for an aircraft's wings to generate the lift needed to keep it airborne. Similarly, this extreme rarefied air offers insufficient resistance for the aerodynamics of a satellite to maintain an orbit within the thermosphere.
Instead, most satellites orbit in the lower layers of the atmosphere, such as the low Earth orbit (LEO), which is between approximately 200 to 2000 kilometers (120 to 1240 miles) above Earth. Some high-altitude satellites may reach the lower parts of the thermosphere, like the Molniya orbit with a maximum altitude of about 40,000 kilometers (25,000 miles), but that is still much lower than most of the thermosphere.
