HAT-P-25 b
HAT-P-25 b is a hot Jupiter orbiting HAT-P-25 in the constellation Aries. It lies about 980 light-years from Earth and was discovered in 2012 using the transit method.
How Big Is HAT-P-25 b?
HAT-P-25 b has a radius of 12.72 times that of Earth, or 1.14 times the radius of Jupiter. Its mass is 181 times that of Earth, giving it a density of 0.48 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is HAT-P-25 b in the Habitable Zone?
HAT-P-25 b orbits inside the inner edge of the habitable zone of HAT-P-25. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HAT-P-25: 0.640–1.519 AU (conservative: 0.810–1.440 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on HAT-P-25 b
The equilibrium temperature of HAT-P-25 b is about 1,182 K (909 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 325 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on HAT-P-25 b — one full orbit around HAT-P-25 — lasts 3.65 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.047 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.023).
How Was HAT-P-25 b Discovered?
HAT-P-25 b was discovered in 2012 using the transit method, with observations from HATNet.
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 HAT-P-25 b?
HAT-P-25 b is 979.7 light-years (300.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1047. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 17,242,720 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. HAT-P-25 b scores 0.07, ranking #4,846 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HAT-P-25
HAT-P-25
- Surface temperature
- 5,519 K (Sun: 5,772 K)
- Mass
- 1.01 M☉
- Radius
- 0.92 R☉
- Luminosity
- 0.7050 L☉
Planetary System
HAT-P-25 b is the only planet known to orbit HAT-P-25 so far.
HAT-P-25 b — Complete Data
| Radius | 12.722 Earth radii (1.135 Jupiter radii) |
|---|---|
| Mass | 180.85 Earth masses (0.569 Jupiter masses) |
| Density | 0.48 g/cm³ (Earth: 5.51) |
| Orbital period | 3.65 days |
| Orbital distance | 0.047 AU |
| Eccentricity | 0.023 |
| Equilibrium temperature | 1,182 K (909 °C) |
| Stellar irradiation | 325.00× Earth |
| Earth Similarity Index | 0.07 |
| Distance from Earth | 979.7 light-years (300.4 parsecs) |
| Constellation | Aries |
| Discovery method | Transit |
| Discovery facility | HATNet |
| Discovery year | 2012 |
Data: NASA Exoplanet Archive, last updated 2019-01-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HAT-P-25 b
Is HAT-P-25 b habitable?
No — HAT-P-25 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HAT-P-25 b?
HAT-P-25 b is about 980 light-years from Earth in the constellation Aries. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 17,242,720 years to get there.
How big is HAT-P-25 b compared to Earth?
HAT-P-25 b has 12.72 times the radius of Earth and about 181 times its mass.
How long is a year on HAT-P-25 b?
One orbit around HAT-P-25 takes 3.7 Earth days — short enough that 100 of its years would fit into one Earth year.
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