Quirks & Quarks

How can planes travel against the rotation of the Earth?

How do planes ever arrive at their destination? Turns out, it's because the air is travelling too

How do planes ever arrive at their destination? Turns out, it's because the air is travelling too

Airplane speed relative to the ground does not change despite the rotation speed of the Earth (David Horemans/CBC)

Today's question comes from Michael Keller in Victoria, British Columbia. He asks: 

Since the Earth is rotating from west to east at a thousand miles an hour how is it that planes flying in the same direction can still reach their destination?

Sara Mazrouei, a planetary and Earth scientist, explains that while the earth is rotating at about 1800 kilometres per hour, that's in comparison to the fixed stars in the sky. But as the Earth rotates, so does the atmosphere, which is held to the surface of the Earth by gravity.

When we say that planes are flying at 900 kilometres per hour, that's relative to the Earth's surface. In the frame of reference of the fixed stars, it would appear much different. 

That being said, it is sometimes faster to go in one direction than another. That isn't because of the earth's rotation, but because of the high-speed, high altitude winds of the jet stream. When you're flying from Canada to Europe, it's quicker because you get that extra boost from the winds, and when you're flying from Europe to Canada, you're going against the flow of the jet stream so it takes more time.

Written and produced by Amanda Buckiewicz



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