EarthSky
Super-Earth
A rocky planet heavier than Earth, up to about twice its size, with no local example.
Between Earth and the sub-Neptunes lies a population of planets up to roughly 1.6 Earth radii that appear to be genuinely rocky. They are common, they are the most promising targets for atmospheric study around small stars, and we have no idea what they are like: the interior of a planet five times Earth's mass is outside anything the solar system offers. Plate tectonics, magnetic fields and volcanism on such a world are all open questions.
Where it has come up lately
Related terms
Transit method
Finding planets by watching a star dim slightly as one passes in front.
Radial velocity
Finding planets by the wobble they induce in their star's motion.
Habitable zone
The orbital band where a planet could hold liquid water — no more than that.
Sub-Neptune
The most common kind of planet in the galaxy, and there is not one in our solar system.
Questions
What is Super-Earth?
A rocky planet heavier than Earth, up to about twice its size, with no local example.
Why does it matter?
They are common, they are the most promising targets for atmospheric study around small stars, and we have no idea what they are like: the interior of a planet five times Earth's mass is outside anything the solar system offers. Plate tectonics, magnetic fields and volcanism on such a world are all open questions.