Yes, the exosphere is considered the least dense layer of Earth’s atmosphere. The exosphere is the outermost layer, situated above the thermosphere, and extends from about 600 kilometers (370 miles) to 10,000 kilometers (6,200 miles) above sea level. In this region, the atmosphere is extremely thin, and the air is so sparse that individual gas molecules can travel hundreds of kilometers without colliding with one another.
In the exosphere, the density of air is so low that it approaches a vacuum. This is significant because it means that traditional atmospheric phenomena, like weather and clouds, do not occur here. Instead, the few particles that exist can escape into space, contributing to the loss of atmospheric gases over time. The primary components found in the exosphere are hydrogen and helium, and the layer gradually transitions into outer space, where there is virtually no atmosphere to speak of.
Overall, the exosphere’s extreme thinness and low density make it unique among the atmospheric layers and a crucial area for understanding how Earth’s atmosphere interacts with space.