All of the planets in our solar system orbit around the Sun. Planets that orbit around other stars are called exoplanets. Exoplanets are very hard to see directly with telescopes. They are hidden by the bright glare of the stars they orbit.
So, astronomers use other ways to detect and study these distant planets. They search for exoplanets by looking at the effects these planets have on the stars they orbit.
One way to search for exoplanets is to look for "wobbly" stars. A star that has planets doesn't orbit perfectly around its center. From far away, this off-center orbit makes the star look like it's wobbling.
In 2009, NASA launched a spacecraft called Kepler to look for exoplanets. Kepler looked for planets in a wide range of sizes and orbits. And these planets orbited around stars that varied in size and temperature.
Kepler detected exoplanets using something called the transit method. When a planet passes in front of its star, it's called a transit. As the planet transits in front of the star, it blocks out a little bit of the star's light. That means a star will look a little less bright when the planet passes in front of it.
In 2009, NASA launched a spacecraft called Kepler to look for exoplanets.
Nature Article | Published: 23 November 1995
A Jupiter-mass companion to a solar-type star
Michel Mayor & Didier Queloz
Nature Volume 378, pages355–359 (1995)