Which planet do most exoplanets that we have discovered resemble?

Extrasolar planets can be found using a range of techniques, but the most straightforward ones are gas giants in near orbits around their stars that transit the star as seen from Earth.

The star's variations in apparent brightness should then be fairly simple to identify.

Obviously, smaller, rocky planets cause much less variation in brightness, even if we are fortunate enough to witness them transit the star from our point of view due to their plane of motion.

Because the Transit technique is one of the most widely used detection methods, the majority of known exoplanets that we have discovered are either confirmed or highly likely to be gas giants.

This method involves examining the light curve of a distant star, which is the variation in brightness over time. While most stars brighten and dim over time, a periodic, large dip in brightness indicates that a large object is passing (or transiting) in front of the star.

Since the dip in the curve caused by a gas giant is larger than that of a smaller planet—the dip in the curve caused by a smaller planet would be obscured by the star's normal dimming and brightening—gas giants account for the majority of exoplanet discoveries.

The light you see on the wall is similar to the light curve of a star. Now, if you pass an object closer to the flashlight than it is to the wall, this also changes the shadow. Suppose you have a flashlight shining on a wall. If you pass a large object through the light beam, it has a large shadow. If you pass a smaller object through, it has a smaller shadow.

For this reason, the majority of exoplanets are referred to as "hot Jupiters"; these are massive gas giants with shorter orbits that are more likely to be discovered in a few weeks or months. They are hot because they pass near the star, creating a larger dip in the curve that is easier to see.

Most exoplanets resemble Earth.