LTT 3780 c
LTT 3780 c is a super-Earth orbiting LTT 3780 in the constellation Hydra. It lies about 72 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is LTT 3780 c?
LTT 3780 c has a radius of 2.39 times that of Earth. Its mass is 8.0 times that of Earth, giving it a density of 3.24 g/cm³ — between that of rocky and gaseous planets.
Is LTT 3780 c in the Habitable Zone?
LTT 3780 c orbits inside the inner edge of the habitable zone of LTT 3780. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of LTT 3780: 0.105–0.275 AU (conservative: 0.133–0.261 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on LTT 3780 c
The equilibrium temperature of LTT 3780 c is about 359 K (86 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 2.76 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on LTT 3780 c — one full orbit around LTT 3780 — lasts 12.3 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.076 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.024).
How Was LTT 3780 c Discovered?
LTT 3780 c was discovered in 2020 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
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 LTT 3780 c?
LTT 3780 c is 71.7 light-years (22.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1955. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,261,920 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. LTT 3780 c scores 0.56, ranking #180 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: LTT 3780
LTT 3780 c belongs to a system of 2 stars; it orbits LTT 3780.
LTT 3780
- Surface temperature
- 3,358 K (Sun: 5,772 K)
- Mass
- 0.38 M☉
- Radius
- 0.38 R☉
- Luminosity
- 0.0165 L☉
- Age
- 3.1 billion years (Sun: 4.6)
The LTT 3780 Planetary System
LTT 3780 c is one of 2 known planets in the LTT 3780 system. Its siblings:
- LTT 3780 b (Super Earth)
LTT 3780 c — Complete Data
| Radius | 2.390 Earth radii (0.213 Jupiter radii) |
|---|---|
| Mass | 8.04 Earth masses (0.025 Jupiter masses) |
| Density | 3.24 g/cm³ (Earth: 5.51) |
| Orbital period | 12.25 days |
| Orbital distance | 0.076 AU |
| Eccentricity | 0.024 |
| Equilibrium temperature | 359 K (86 °C) |
| Stellar irradiation | 2.76× Earth |
| Earth Similarity Index | 0.56 |
| Distance from Earth | 71.7 light-years (22.0 parsecs) |
| Constellation | Hydra |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2024-03-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About LTT 3780 c
Is LTT 3780 c habitable?
No — LTT 3780 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is LTT 3780 c?
LTT 3780 c is about 72 light-years from Earth in the constellation Hydra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,261,920 years to get there.
How big is LTT 3780 c compared to Earth?
LTT 3780 c has 2.39 times the radius of Earth and about 8.0 times its mass.
How long is a year on LTT 3780 c?
One orbit around LTT 3780 takes 12.3 Earth days — short enough that 30 of its years would fit into one Earth year.
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