A cool super-Earth in a five-planet system
Kepler-62f
Orbits Kepler-62 · 980 light-years · discovered 2013 (transit)
Kepler-62f is the outermost of five known planets orbiting an orange dwarf star about 980 light-years away in the constellation Lyra. About 40% larger than Earth, it lies in the outer part of its star's habitable zone and receives around 40% of the energy Earth gets from the Sun.
When it was announced in 2013, together with its neighbour Kepler-62e, it was among the smallest planets then known in a habitable zone. Whether it is warm enough for liquid water depends on an atmosphere that has never been observed, and its mass and composition remain unknown.
Key facts
- Star
- Kepler-62K2V orange dwarf
- Distance
- 980 light-years
- Radius
- 1.41 × Earth
- Mass
- Not measured
- Orbital period
- 267.3 days
- Equilibrium temperature
- 208 K (-65 °C)Before any greenhouse warming
- Starlight received
- 0.41× Earth's
- Surface gravity
- ≈ 1.79 gRough estimate (rocky composition assumed)
- Discovered
- 2013Transit
- Star
- Kepler-62 (K2V orange dwarf)
- Distance
- About 980 light-years
- Discovered
- 2013, transit (Kepler)
- Radius
- About 1.4 Earth radii
- Mass
- Not measured — estimated at roughly 2–3 Earth masses if rocky
- Orbital period
- About 267 days
- Starlight received
- Roughly 40% of what Earth gets from the Sun
- Equilibrium temperature
- About 208 K (−65 °C), a simple estimate that ignores any atmosphere
- Constellation
- Lyra
Measured values follow the NASA Exoplanet Archive and discovery papers; many carry large uncertainties. The 3D globe and walkable surface on this page are an artist's impression generated from these numbers.
What we know
Kepler-62f's size and orbit come from transits recorded by Kepler: about 1.4 Earth radii and a year of roughly 267 days. Its mass has not been measured, because its pull on its star is far too small to detect with current instruments at this distance.
At around 1.4 Earth radii, it is small enough that a rocky composition is plausible. It could also contain a large fraction of water. Without a mass, its density is unknown.
Its star
Kepler-62 is an orange dwarf somewhat smaller and cooler than the Sun, shining at roughly a fifth of its brightness. It is thought to be several billion years old, likely older than the Sun. Its five known planets range from hot inner worlds on orbits of under three weeks out to Kepler-62f far out in the habitable zone.
Could it be habitable?
With only about 40% of Earth's sunlight, Kepler-62f would be frozen with an atmosphere like Earth's today. Climate modelling has suggested that a thicker atmosphere with much more carbon dioxide could warm it enough to keep at least part of its surface above freezing.
Some studies have also proposed that, if it is rich in water, it could be an ocean world. These are possibilities explored in models, not observations. Its orange host star is a relatively gentle neighbour compared with flaring red dwarfs, which may help any atmosphere survive.
Orbit and climate
Kepler-62f orbits about 0.72 astronomical units from its star, close to Venus's distance from the Sun, but its dim star leaves it chilly. Its wide orbit means it is unlikely to be tidally locked. Depending on its tilt and orbital shape, models suggest it could have strong seasons.
Discovery
A team led by William Borucki announced the Kepler-62 system in April 2013 in the journal Science. The planets were validated statistically, using Kepler data and follow-up observations from other telescopes, to rule out other causes of the signals.
Kepler-62e
The neighbouring planet Kepler-62e, about 1.6 times Earth's width, orbits closer in, every 122 days, near the inner part of the habitable zone.
Future observations
The Kepler-62 system is too faint and distant for JWST to examine Kepler-62f's atmosphere in useful detail. Its importance lies in showing that compact systems with multiple small planets can include worlds in the habitable zone of a star not too different from the Sun.
About the 3D impression
Artist's impression — the real surface has never been seen. The globe and the surface you can walk on are generated from what is measured — size, the starlight it receives and the kind of star it orbits — using the same procedural engine as our imaginary worlds. Seas, ice, clouds and any plant-like colours are possibilities, not observations: around a red dwarf the daylight is redder, so the scene uses warmer skies and darker vegetation.
Earth-like exoplanets compared
| Planet | Distance | Radius | Year | Sunlight |
|---|---|---|---|---|
| Proxima Centauri b | 4.2 ly | — | 11.2 days | 0.65× Earth |
| Ross 128 b | 11.0 ly | — | 9.87 days | 1.38× Earth |
| Teegarden's Star b | 12.5 ly | — | 4.91 days | 1.08× Earth |
| Gliese 667 Cc | 23.6 ly | — | 28.1 days | 0.88× Earth |
| TRAPPIST-1d | 40.5 ly | 0.79 R⊕ | 4.05 days | 1.11× Earth |
| TRAPPIST-1e | 40.5 ly | 0.92 R⊕ | 6.10 days | 0.65× Earth |
| TRAPPIST-1f | 40.5 ly | 1.04 R⊕ | 9.21 days | 0.37× Earth |
| TRAPPIST-1g | 40.5 ly | 1.13 R⊕ | 12.4 days | 0.25× Earth |
| LHS 1140 b | 48.9 ly | 1.73 R⊕ | 24.7 days | 0.43× Earth |
| TOI-700 d | 101 ly | 1.07 R⊕ | 37.4 days | 0.87× Earth |
| Kepler-186f | 580 ly | 1.17 R⊕ | 129.9 days | 0.30× Earth |
| Kepler-22b | 635 ly | 2.10 R⊕ | 289.9 days | 1.01× Earth |
| Kepler-62f | 980 ly | 1.41 R⊕ | 267.3 days | 0.41× Earth |
| Kepler-442b | 1,194 ly | 1.34 R⊕ | 112.3 days | 0.70× Earth |
| Kepler-452b | 1,800 ly | 1.63 R⊕ | 384.8 days | 1.10× Earth |
Surprising facts about Kepler-62f
- Kepler-62f orbits at roughly Venus's distance from its star, yet receives well under half the energy Earth gets from the Sun.
- Its year lasts about 267 days, roughly nine Earth months.
- The Kepler-62 system contains two planets in or near the habitable zone, Kepler-62e and Kepler-62f.
- Its host star is thought to be older than the Sun, giving any life there a long head start — if life exists at all.