Extrasolar planets are called exoplanets and these are worlds that orbit other stars.
Both ground and space-based telescopes and observatories have found thousands of possible exoplanets.
Almost 2,000 of the exoplanets have been confirmed and the rest await study from astronomers to make sure that they are planets. Given the billions of galaxies, astronomers estimate that there is a good possibility that there are trillions of planets orbiting other stars.
If you look at our solar system you will see that planets exist in all sizes, orbital positions and masses.
The same ruling is used when you talk about any exoplanet. They can be as small as the Earth or as gigantic as the super worlds like Jupiter.
Their orbits can be close to the sun like Venus very far away from their parent sun.
Astronomers are finding and measuring atmospheres around far away exoplanets. Knowing information about the atmosphere can help them understand more about the planet itself.
Some of the characteristics that astronomers use to determine if a celestial body is an exoplanet include: temperature of the surface, the magnetic field, orbit, and even an exoplanet’s color.
Astronomers group types of exoplanets as: Earth-size, Earth-like, Super-Jupiters, gas giants, rocky worlds the size of Earth, rocky giants, Super-Earths, mini-Neptunes, and gas dwarfs.
Scientists have found at least one exoplanet to contain an exomoon. In another case, the exoplanet is too close to its star and is leaving behind a trail of vapor.
The goal of researching exoplanets is to also find out which are the most Earth-like.
The area around a star that allows an exoplanet to have liquid water on the surface of a solid planet is called “the habitable zone.”
Some explain this as the “Goldilocks Zone.” Not to hot and not too cold.
Those worlds that are positioned in the habitable zone are the ones that are the best candidates for supporting life.
Where once we thought that there weren’t that many potential exoplanets that could support life, we are now finding that over 22% of the Sun-like stars being researched have Earth-sized exoplanets in their habitable zones.
The Kepler Mission was designed to seek out distant worlds and is continuing its mission today. There are many missions around the globe that are assisting in finding exoplanets.
Some of these include: the Hubble Space Telescope, the CoROT mission from the European Space Agency, the WISE mission, and the Herschel spacecraft.