What is the scientific name for the highest level of the Earth's atmosphere?
The exosphere stretches up to 10,000 kilometers and represents the last official layer of the atmosphere. It's so thin that some argue it actually isn't a part of the Earth at all since it's similar to the conditions of outer space. Regardless, the exosphere is home to orbiting satellites and sits over the thermosphere, mesosphere, stratosphere and troposphere, descending in that order. The ionosphere is a separate region which reaches across the other layers. Source: NASA, UCAR