Mayor & Queloz · First exoplanet
Do other stars have planets?
That time, that place
That other stars have planets was an old guess. The problem was that there was no way to see one.
A planet does not shine, and the star beside it is billions of times brighter. It is like looking for a firefly next to a lighthouse.
Why this question
So they turned it around: look at the star, not the planet.
A planet in orbit tugs its star into a small wobble. As the star moves toward us and away, the color of its light shifts minutely. If that wobble repeats on a cycle, something is going around it.
It meant detecting motion of a few tens of meters per second.
What was found
Mayor and Queloz caught that wobble in a star in Pegasus.
The result was unexpected: the period was 4.2 days. A planet the size of Jupiter was hugging its star, completing an orbit in four days.
By the standards of our solar system this is impossible — giant planets form far out where it is cold. Many first assumed an error in the analysis.
Once confirmed, what had to be rewritten was not the observation but the theory: planets do not necessarily stay where they were born, and can migrate inward.
Planets stay where they form
A minute shift in a star's color repeating every 4.2 days
More than five thousand exoplanets have been found since. Our solar system is not the standard