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Do Planets Change Speed When Orbiting the Sun?

-- Goody | October 18, 2020
Arecibo-GBT radar image of Maxwell Montes

Question:

Do planets speed up as they move closer to the sun and then slow down as they go away from the sun?

-- Goody

Answer:

Yes.  The speed at which a planet orbits the Sun changes depending upon how far it is from the Sun.  When a planet is closer to the Sun the Sun’s gravitational pull is stronger, so the planet moves faster.  When a planet is further away from the sun the Sun’s gravitational pull is weaker, so the planet moves slower in its orbit.

-- Jeff Mangum