Atmosphere of Mercury facts for kids

Mercury has a very thin atmosphere, which is often called an "exosphere." This means it's so thin that its particles don't often bump into each other. It contains gases like hydrogen, helium, oxygen, sodium, calcium, potassium, and even a tiny bit of water vapor. The total pressure of this atmosphere is extremely low, about 100 trillion times less than Earth's atmosphere! These gases might come from the Sun's solar wind or from the surface of Mercury itself.

What is Mercury's Atmosphere Made Of?

Mercury's atmosphere is made up of different elements. These elements can come from two main places: the solar wind (a stream of particles from the Sun) or from Mercury's rocky surface.

The first elements found were atomic hydrogen, helium, and atomic oxygen. Scientists saw these using a special tool called an ultraviolet photometer on the Mariner 10 spacecraft in 1974. The hydrogen and helium are thought to come from the solar wind. The oxygen, however, probably comes from Mercury's crust, which is its outer rocky layer.

Later, in 1985, scientists Drew Potter and Tom Morgan discovered sodium in Mercury's exosphere. The very next year, they also found potassium. In 1998, calcium was added to the list of elements found. More recently, the MESSENGER spacecraft discovered magnesium in Mercury's thin atmosphere.

Images for kids

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  Calcium and Magnesium in Mercury's tail

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  Sodium tail, photographed by an amateur in Italy

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  Sodium tail

See also

In Spanish: Atmósfera de Mercurio para niños