Intro to Astronomy

study guides for every class

that actually explain what's on your next test

Retrograde motion

from class:

Intro to Astronomy

Definition

Retrograde motion is the apparent backward movement of a planet against the background of stars. This phenomenon occurs when Earth, which moves faster in its orbit, overtakes and passes an outer planet.

congrats on reading the definition of retrograde motion. now let's actually learn it.

ok, let's learn stuff

5 Must Know Facts For Your Next Test

  1. Retrograde motion was a significant puzzle for ancient astronomers who believed in geocentric models.
  2. It typically affects the outer planets like Mars, Jupiter, and Saturn.
  3. The phenomenon is best explained by the heliocentric model proposed by Copernicus.
  4. Retrograde motion occurs periodically as Earth catches up to and passes these slower-moving outer planets.
  5. The term 'retrograde' means 'moving backward,' but this motion is only apparent from Earth's perspective.

Review Questions

  • What causes retrograde motion?
  • Which model of the solar system provides a clear explanation for retrograde motion?
  • Why did ancient astronomers find retrograde motion puzzling?
© 2024 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.
Glossary
Guides