---
title: Super-Earth
summary: A planet more massive than Earth but lighter than Neptune, usually rocky, with no counterpart in the Solar System. Super-Earths are among the most common planets found around other stars.
science_status: [observed, model, sim]
categories: [Planets, Planet classes, Super-Earths, Exoplanets]
aliases: [Super-Earths, Super Earth, SET, SEV, SVT, SEI, SE2-T, SE3-V, SE3-V-TL, SE4-I, Temperate super-Earth, Volcanic super-Earth, Ice super-Earth, Icy super-Earth, Rocky super-Earth]
infobox:
  type: planet_class
  name: Super-Earth
  code: "SET (temperate), SEV (volcanic), SVT (volcanic, tidally locked), SEI (ice)"
  legacy_code: "SE2-T, SE3-V, SE3-V-TL, SE4-I"
  level: series
  series: "Super-Earth (SE)"
  science_status: [observed, model, sim]
  image: File:Super-Earth_sim.avif
  literature_equivalent: "Super-Earth: roughly 1 to 10 Earth masses, or about 1.25 to 2 Earth radii; the rocky population below the radius valley"
  defining_criteria_sim: "Planets of 2 to 10 Earth masses without a thick hydrogen envelope, split by temperature and activity into temperate, volcanic and icy families"
  mass_earth: {observed: "about 1 to 10", sim: "2.5 to 10 (SET); 2 to 8 (SEV, SVT); 2 to 7 (SEI)"}
  radius_earth: {observed: "about 1.25 to 1.6 for rocky compositions; larger if water-rich"}
  density_g_cm3: {observed: "about 5 to 8 for rocky super-Earths; lower if water-rich"}
  surface_gravity_m_s2: {model: "about 1.5 to 2.5 g for rocky planets of 3 to 8 Earth masses"}
  interior: "Iron core, silicate mantle; the more massive, the more compressed. Water-rich versions add deep oceans or high-pressure ice"
  tidal_state: "Close-in super-Earths are tidally locked"
  typical_orbit: "Most known ones orbit within about 0.3 AU, because transit and radial-velocity surveys find those most easily"
  occurrence_observed: "About a quarter of Sun-like stars host a planet of 1 to 2 Earth radii with a period of 5 to 100 days"
  frequency_in_sim: "658 of 8,742 generated planets (SEI 309, SET 215, SEV 128, SVT 6), in the committed sheets as of 2026-09-27"
  real_examples: ["LHS 1140 b", "TOI-1452 b", "Kepler-10 b", "CoRoT-7 b", "55 Cancri e", "OGLE-2005-BLG-390Lb (cold)"]
  subtypes: ["SET-OC Deep-ocean temperate", "SEV-AV Active volcanic", "SVT-HS Hemispheric (tidally locked volcanic)", "SEI-CR Cryovolcanic resurfacer", "SEI-DS Ancient dark shell", "SEI-HI High-pressure ice barrier", "SEI-TS Tholin-stained", "SEI-NG Nitrogen glacier", "SEI-HS Haze-shrouded"]
  sim_source: "Super-Earth physics engines (temperate, volcanic, ice); super-Earth science sets SET_00 to SET_19 and SEI_00 to SEI_19"
  last_verified: 2026-09-27
sim:
  entity: [planet_class.SET, planet_class.SEV, planet_class.SVT, planet_class.SEI]
refs:
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    title: "The Mass-radius Relation for 65 Exoplanets Smaller Than 4 Earth Radii"
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    type: article-journal
    author: [{family: "Valencia", given: "Diana"}, {family: "O'Connell", given: "Richard J."}, {family: "Sasselov", given: "Dimitar D."}]
    title: "Inevitability of Plate Tectonics on Super-Earths"
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    issued: 2007
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images_wanted:
  - file: File:Super-Earth_sim.avif
    subject: "Sim renders of three super-Earths side by side at the same scale as Earth: a temperate deep-ocean world (SET-OC), a volcanic world (SEV-AV) and an icy world (SEI-CR)"
    source: sim
    note: "Shot list: render the three plates on the lit sphere with an Earth plate for scale; label 'Sim render'. Confirm the plate generator's licence."
  - file: File:Super-Earth_mass_radius.svg
    subject: "Diagram: mass against radius for well-measured small exoplanets, with curves for iron, Earth-like rock, 50% water and rock with 1% hydrogen, and the radius valley marked"
    source: other
    note: "To be drawn by us from the NASA Exoplanet Archive; label 'Diagram'."
---

A **super-Earth** is a planet more massive than Earth but well below the mass of Neptune, roughly 1 to 10 times Earth's mass. The name refers only to size: a super-Earth can be a lava world, an ice world or anything between. The Solar System has none, yet super-Earths and their slightly larger cousins, the [[Mini-Neptune|mini-Neptunes]], turned out to be among the commonest planets in the Galaxy's inner planetary systems. They are the best targets for studying rocky planets outside the Solar System, and some of them are candidates for habitable worlds.

::figure{src="File:Super-Earth_mass_radius.svg" size=wide alt="A log-log plot of planet mass against radius with composition curves; rocky super-Earths cluster along the Earth-like rock line below 1.6 Earth radii." caption="Diagram: small exoplanets with measured masses and radii. Rocky super-Earths follow the Earth-like composition curve; above about 1.6 Earth radii most planets need water or hydrogen to explain their size."}

## Characteristics

### What counts

Definitions vary. NASA describes super-Earths as planets more massive than Earth but lighter than Neptune, typically 2 to 10 Earth masses, which may or may not have atmospheres :cite[nasa_types]. Surveys that measure only size often use radius: the Kepler mission's super-Earth bin ran from 1.25 to 2 Earth radii :cite[fressin2013]. Since the discovery of the [[Radius valley]], a shortage of planets between about 1.5 and 2 Earth radii, many astronomers reserve the term for the rocky population below it, and call the planets above it sub-Neptunes or mini-Neptunes :cite[fulton2017].

### Size, mass and composition

Rock compresses under its own weight, so a larger rocky planet is denser. The radius of a rocky planet rises only slowly with mass, roughly as

$$
R \approx R_\oplus \left(\frac{M}{M_\oplus}\right)^{0.27\text{ to }0.28},
$$

a relation seen both in interior models and in the planets themselves :cite[chen2017] :cite[zeng2016]. A planet of Earth's composition and 5 Earth masses is only about 1.5 to 1.6 times Earth's radius, and its density is around 7 to 8 g/cm³. Measured planets follow this pattern up to about 1.5 Earth radii, where density peaks; larger planets become less dense again, because they carry lighter material :cite[weiss2014]. By about 1.6 Earth radii, most planets are too large to be pure rock :cite[rogers2015]. Fitting the known planets separately, Otegi and colleagues found a rocky population following $R = 1.03\,M^{0.29}$ in Earth units and a volatile-rich one that is much larger at the same mass :cite[otegi2020].

The same mass and radius can be matched by different interiors: an iron-rich rocky planet, a lighter rocky planet, or rock with a layer of water, or with a thin hydrogen envelope. Water-rich super-Earths, if they exist, would be a distinct kind: models put planets of half rock and half water on a curve well above the rocky one :cite[zeng2019], and a group of planets around red dwarfs with densities in that range has been proposed as water worlds, though the interpretation is contested :cite[luque2022].

### Gravity and surface

Surface gravity scales as $M/R^2$. For a rocky planet following the relation above, that grows roughly as $M^{0.46}$: a 5 Earth-mass rocky super-Earth has about twice Earth's surface gravity, and a 10 Earth-mass one nearly three times. Stronger gravity holds an atmosphere more tightly and squeezes the planet's mantle.

### Plate tectonics

Whether super-Earths have plate tectonics has been argued both ways. One model found that larger planets have thinner, weaker plates driven by stronger convection, making plate tectonics inevitable :cite[valencia2007]; another, published the same year, found that the extra heat and pressure make a stagnant lid, a single rigid shell as on Venus or Mars, more likely :cite[oneill2007]. The answer matters for habitability, because plate tectonics recycles carbon and drives the climate thermostat described on [[Mixed world]]. Heller and Armstrong suggested that a planet of about twice Earth's mass could be more hospitable than Earth, with longer-lived tectonics and a stronger magnetic field :cite[heller2014].

## Formation

Many close-in super-Earths are probably not born bare. The shape and slope of the radius valley suggest that most of them began with a thin envelope of hydrogen and helium, and lost it to their stars' radiation or their own internal heat, leaving the rocky cores seen today :cite[vaneylen2018] (see [[Radius valley]]). Others may have formed after the gas in their stars' discs had largely gone, too late to gather much hydrogen. Planets that assembled farther out, beyond the snow line, could include large amounts of water ice and migrate inward as water-rich super-Earths. Far from their stars, super-Earths would keep their ices, like the cold planets of about 5 Earth masses that gravitational microlensing has found beyond the snow lines of their stars :cite[beaulieu2006].

## How we know

Super-Earths are found in large numbers by transits and radial velocity. Kepler showed that planets of 1 to 2 Earth radii orbit about a quarter of Sun-like stars on orbits of 5 to 100 days :cite[petigura2013], and that small planets are about as common around F, G and K stars alike :cite[fressin2013]. From Kepler data, somewhere between about a third and two-thirds of Sun-like stars may host a rocky planet in the habitable zone :cite[bryson2021].

The first rocky super-Earths with measured sizes and masses were hot. **CoRoT-7 b**, announced in 2009, was the first super-Earth with a measured radius :cite[leger2009]; **Kepler-10 b** was Kepler's first confirmed rocky planet, in 2011 :cite[batalha2011]. Both orbit their stars in less than a day and are [[Lava world|lava worlds]]. JWST is now measuring their atmospheres: **55 Cancri e**, a super-Earth of about 8 Earth masses on an 18-hour orbit, shows evidence of an atmosphere of carbon dioxide or carbon monoxide rather than bare rock :cite[hu2024].

Temperate super-Earths are harder to find, because their longer orbits give fewer transits. The best studied is **LHS 1140 b**, 5.6 Earth masses and 1.73 Earth radii, in the habitable zone of a red dwarf 49 light years away. Its density is too low for pure rock, making it either a water world or a planet with a thin hydrogen envelope :cite[cadieux2024a], and JWST has ruled out a thick hydrogen atmosphere :cite[cadieux2024b]. **TOI-1452 b**, about 4.8 Earth masses and 1.67 Earth radii around a red dwarf, is another temperate candidate whose density leaves room for a large fraction of water :cite[cadieux2022].

## Notable examples

| Planet | Mass | Radius | Orbit | Notes |
|---|---|---|---|---|
| Kepler-10 b | about 3.3 M⊕ | 1.47 R⊕ | 20 hours | rocky lava world |
| CoRoT-7 b | about 4.7 M⊕ | about 1.6 R⊕ | 20.5 hours | first super-Earth with a measured radius |
| 55 Cancri e | 8.0 M⊕ | 1.88 R⊕ | 18 hours | probable CO or CO₂ atmosphere (JWST) |
| LHS 1140 b | 5.6 M⊕ | 1.73 R⊕ | 25 days, habitable zone | water world or thin hydrogen envelope |
| TOI-1452 b | about 4.8 M⊕ | 1.67 R⊕ | 11 days, habitable zone | possibly water-rich |
| OGLE-2005-BLG-390Lb | about 5.5 M⊕ | unknown | about 2.6 AU, around 50 K | cold, found by microlensing |

:::callout{type=sim title="In Pax Abyssi"}
The sim has three families of super-Earth, all of 2 to 10 Earth masses without a thick hydrogen envelope. **Temperate super-Earths** (SET) sit in or near the habitable zone and are currently generated as deep-ocean worlds (SET-OC), with thick atmospheres of 1.5 to 10 bar; their sizes put them among the water-rich super-Earths described above. **Volcanic super-Earths** are geologically active worlds; those that are tidally locked (SVT-HS) show a stark contrast between a volcanic day side and a dark night side, and the rest are active volcanic worlds (SEV-AV). **Ice super-Earths** (SEI) orbit far out and have six subtypes: cryovolcanic resurfacers (SEI-CR), ancient dark shells (SEI-DS), worlds with a barrier of high-pressure ice in the heaviest planets (SEI-HI), tholin-stained surfaces (SEI-TS), nitrogen glaciers below 63 K (SEI-NG) and haze-shrouded worlds (SEI-HS). Real exoplanets in the catalogue are sorted into these families by mass, temperature and radius. In the committed system sheets, 658 of 8,742 generated planets are super-Earths. In the game each is drawn as a prebaked texture plate chosen by its subtype code.
:::

## See also

- [[Radius valley]]
- [[Mini-Neptune]]
- [[Mixed world]]
- [[Ocean world]]
- [[Lava world]]
- [[Ice world]]
- [[Superhabitable worlds]]
- [[Planet occurrence]]
- [[Planet classification]]