The planet is also the only terrestrial planet known to have a hydrosphere.

The largest exoplanet ever discovered is also one of the strangest and theoretically should not even exist, scientists say. Earth is the largest rocky planet. A planet roughly half the size of Neptune might be 100 percent rock, making it the largest known rocky world. Of the four terrestrial planets, the Earth is the largest having an equatorial radius 3,958.8 miles. Discover satisfies everyday curiosity with relevant and approachable science news, feature articles, photos and more. Credit: JPL-Caltech/NASA. ... Jupiter may be the largest and most massive planet in the Solar System, but adding more mass to it would only make it smaller. Largest rocky world found by Evan Gough, Universe Today An illustration of a large, rocky planet similar to the recently discovered BD+20594b.

What’s the largest planet in the Universe? From this article: “The largest “terrestrial” planet is generally considered the one before you get too thick of an atmosphere, which happens at about 5-10 Earth masses (something like 2 Earth radii). An illustration of a large, rocky planet similar to the recently discovered BD+20594b. ... rocky cores inside. After Earth is Venus, then Mars, and then the smallest, Mercury. Those planets are more Earth-like than Neptune-like.” The problem is the transition from "rocky" to "gas giant" is not well defined. Earth is the third closest planet to the Sun with its distance from the Sun of 92,955,902 miles making up 1 AU (astronomical unit).