Forces and Motion | Electricity and Magnetism

Separating ideas of gravity and atmosphere

Teaching Guidance for 5-11 11-14 Supporting Physics Teaching

There is gravity in space

Wrong Track: There is no gravity in space or on the Moon because there is no air there.

Right Lines: The gravitational force does not depend upon the presence of an atmosphere.

Atmosphere and gravity

Thinking about the learning

Orbiting astronauts are seen to float about in their spacecraft. This is often attributed, incorrectly, to there being no gravity up there in space. This is one of the most common misconceptions about space. A reason often given for this assertion is that the space craft is above the Earth's atmosphere. Therefore, because there is no atmosphere there is no gravity. The same logic is used to explain the fact that lunar astronauts must wear large heavy boots because there is no gravity on the Moon, because there is no atmosphere.

These clips are worth watching and listening to carefully:

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Thinking about the teaching

This misunderstanding, which involves making a direct link between gravity and atmosphere, is a regular visitor to science classrooms.

A video clip of Apollo 15 astronaut Dave Scott dropping a feather and hammer on the surface of the Moon in 1971 is evidence that things do fall on the Moon – there is plenty of gravity there, but no atmosphere.

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