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A rocky planet or terrestrial planet or telluric planet is a planet of mostly rock (e.g., silicates), such as Mercury, Venus, Mars or Earth. Among extra-solar planets, there are also larger such planets, such as those termed super-Earths and mega-Earths.
There is a presumed (and real?) correlation between planets being rocky and the amount of received electromagnetic radiation and stellar wind from the host star, thus how close they are to the star. A very thick atmosphere as per a gas giant would not last if the planet were too close, due to the atmospheric escape factors associated with being close to the host star.
There is presumed to be something of an upper limit on the size of rocky planets.