Dune. Star Wars. Alien. Science fiction movies love alien worlds, and so do we. But how do scientists find planets outside our solar system in real life?
Astronomers have found thousands of planets outside our solar system: planets with super-long elliptical orbits, giant planets with tiny orbits and planets that spin in the opposite direction of their stars.
One of the methods astronomers use to detect these planets is looking at a nearby star's behavior – and seeing if it wiggles!
Why "wiggle"?
Isaac Newton's third law of motion states that for every action there is an equal and opposite reaction. So, when planets feel a gravitational pull towards their suns, they also exert a force on the much larger stars they orbit. Those planetary tugs make the stars wiggle in the sky.
This movement is so small that it can't be detected by human eyes or by most telescopes.
In the past, researchers have measured the speed of these wiggles via the Doppler method, carefully analyzing how the star's light shifts. Now, scientists can observe that physical wiggle in detail.
That's because of a new telescope called GAIA, which is capable of measuring the precise positions of stars — and their movements. Using GAIA data, astronomers have already found one exoplanet, GAIA 4b.
"This is the beginning of the next big phase of exoplanet discovery," says Josh Winn, a professor of astronomy at Princeton University.
Winn is one of the astronomers who discovered GAIA 4b. He says analyzing more GAIA data could yield thousands more exoplanets — and a better understanding of planetary systems as a whole.
Want to hear more about exoplanet discoveries? Send us an email at shortwave@npr.org.
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This episode was produced by Hannah Chinn and edited by Berly McCoy. Tyler Jones checked the facts. Kwesi Lee was the audio engineer.
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