Kepler-25 b
Kepler-25 b is a mini-Neptune orbiting Kepler-25 in the constellation Lyra. It lies about 793 light-years from Earth and was discovered in 2011 using the transit method.
How Big Is Kepler-25 b?
Kepler-25 b has a radius of 2.75 times that of Earth. Its mass is 8.7 times that of Earth, giving it a density of 2.32 g/cm³ — between that of rocky and gaseous planets.
Is Kepler-25 b in the Habitable Zone?
The position of Kepler-25 b relative to the habitable zone of Kepler-25 cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on Kepler-25 b — one full orbit around Kepler-25 — lasts 6.24 Earth days, shorter than Mercury's 88-day year. Its orbit is nearly circular (eccentricity 0.003).
How Was Kepler-25 b Discovered?
Kepler-25 b was discovered in 2011 using the transit method, with observations from Kepler.
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is Kepler-25 b?
Kepler-25 b is 793.4 light-years (243.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1233. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 13,963,840 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. Kepler-25 b scores 0.22, ranking #3,627 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-25
Kepler-25 b belongs to a system of 2 stars; it orbits Kepler-25.
Kepler-25
- Mass
- 1.17 M☉
- Radius
- 1.32 R☉
The Kepler-25 Planetary System
Kepler-25 b is one of 3 known planets in the Kepler-25 system. Its siblings:
- Kepler-25 c (Neptune-like)
- Kepler-25 d (Cold Gas Giant)
Kepler-25 b — Complete Data
| Radius | 2.748 Earth radii (0.245 Jupiter radii) |
|---|---|
| Mass | 8.70 Earth masses (0.028 Jupiter masses) |
| Density | 2.32 g/cm³ (Earth: 5.51) |
| Orbital period | 6.24 days |
| Eccentricity | 0.003 |
| Earth Similarity Index | 0.22 |
| Distance from Earth | 793.4 light-years (243.2 parsecs) |
| Constellation | Lyra |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2011 |
Data: NASA Exoplanet Archive, last updated 2019-06-07. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-25 b
Is Kepler-25 b habitable?
Kepler-25 b is not known to orbit within the habitable zone of Kepler-25, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is Kepler-25 b?
Kepler-25 b is about 793 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 13,963,840 years to get there.
How big is Kepler-25 b compared to Earth?
Kepler-25 b has 2.75 times the radius of Earth and about 8.7 times its mass.
How long is a year on Kepler-25 b?
One orbit around Kepler-25 takes 6.2 Earth days — short enough that 59 of its years would fit into one Earth year.
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