The outermost portion of the Earth's or Moon's atmosphere from which gases can escape into outer space.
Literally, outer sphere. The outermost portion of the Earth's atmosphere, merging, at heights of perhaps 1000 miles, with the interplanetary medium.
the outermost atmospheric layer
The uppermost layer of our atmosphere, coming directly above the thermosphere. It stretches to 10,000 km above our planetâ€(tm)s surface.
The part of the Earth atmosphere above the thermosphere which extends into space. H and He atoms can attain escape velocities at the outer rim of the exosphere.
The layer of the atmosphere lying above 400 km altitude. More Information.
The uppermost layer of the atmosphere, its lower boundary is estimated at 500 km to 1000 km above the Earth's surface. It is only from the exosphere that atmospheric gases can, to any appreciable extent, escape into outer space.
the upper most layer of the earth's atmosphere; the only layer where atmospheric gases can escape into outer space
The outermost layer of the Earth's atmosphere.
The outermost, or topmost, portion of the atmosphere. It is only from the exosphere that atmospheric gases can, to any appreciable amount escape into outer space.
Outermost fringe of Earth's atmosphere.
This region is considered the very outer limits of the earth's atmosphere. Its lower boundary is often called the critical level of escape, where gas atoms are so widely spaced that they rarely collide with one another and have individual orbits. It is estimated to be some 400 plus miles (640 kilometers) above the surface. Related term: ionosphere