Exosphere facts for kids
The exosphere is the very top layer of Earth's atmosphere. It's like the outer edge of our planet's air, blending into space.
This layer has very few molecules, which are tiny particles of gas. The lightest gases, like hydrogen and helium, are found here. Heavier gases, such as carbon dioxide and oxygen atoms, stay closer to the bottom of this layer.
Because there are so few molecules, they hardly ever bump into each other. This means the idea of atmospheric pressure (the weight of the air pushing down) doesn't really apply here.
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Where is the Exosphere?
The exosphere has two main boundaries.
The Lower Boundary
The lower boundary is called the exobase. It's about 500 to 800 kilometers (300 to 500 miles) above Earth's surface. This boundary is also known as the thermopause because it sits between the exosphere and the thermosphere below it.
The gas particles in this area move extremely fast. Scientists estimate the temperature here can range from 0 to 1700 degrees Celsius!
The Upper Boundary
The upper boundary of the exosphere is much farther out. It's where the sun's radiation pressure (the force of sunlight) on hydrogen atoms becomes stronger than Earth's gravity pulling them back.
This point is about halfway to the Moon, or around 200,000 kilometers (124,000 miles) from Earth.
What is the Geocorona?
The exosphere can actually be seen from space! It looks like a faint glow around Earth and is called the geocorona. This glow extends at least 10,000 kilometers (6,200 miles) from our planet's surface.
See also
In Spanish: Exosfera para niños
