Exoplanets

In school, most of us get to learn about planets like Earth, Venus, Mars, and Jupiter and grow very accustomed to the planets within our Solar System. However, if we zoom out into the rest of the Milky Way and even other galaxies, then it becomes apparent that there are many, many other planets out there, orbiting many, many stars. These planets are known as exoplanets, planets which aren't in the Solar System. A few thousand have so far been discovered but there's theorized to be billions within our galaxy alone. However, our observations are a bit biased because most of the exoplanets discovered are close to their star when there could be ones farther away.

Of course, in the search for exoplanets outside our Solar System, there is also an ongoing search for habitable planets for extraterrestrial life. While extraterrestrial life doesn't necessarily mean extremely advanced aliens like the ones you'd see in sci-fi, a handful of exoplanets are theorized to be able to sustain life like Earth. In order to narrow down habitable planets, scientists use something known as the habitable zone. If a planet is in the habitable zone, there is a good chance that it can support liquid water under proper atmospheric pressure conditions. This is believed to be important for the growth of life on exoplanets because these conditions were extremely key to making life here.

While every exoplanet is technically unique, there are many similarities that exoplanets share, as do all planets.

One class of exoplanets is known as a Hot Jupiter, which is basically planets that have sizes and masses similar to Jupiter but orbit really close to their star. They get the "hot" description from the fact that their temperatures are so warm due to their close-range orbits. These can be easily detected because they are so massive. Since they are so massive and close to their stars, when they orbit, the stars will also move enough for us to detect them.

Another class of exoplanets is super-Earths, also sometimes known as "mini Neptunes". These are planets that are more massive than Earth but less massive than ice giants like Neptune and Uranus. Many super-Earths tend to be in the habitable zone and have better chances of being habitable. This would make sense because you'd expect a planet like Earth to be habitable if Earth is itself habitable.

The following links will take you to some fairly known exoplanets that astronomers have located:

Proxima Centauri B

Ross-128 B

Trappist-1e

Kepler-186f

Tres-2b