AU Mic d
AU Mic d is a terrestrial planet orbiting the M1 V star AU Mic in the constellation Microscopium. It lies about 32 light-years from Earth and was discovered in 2023 using the transit timing variations method.
Is AU Mic d in the Habitable Zone?
The position of AU Mic d relative to the habitable zone of AU Mic cannot be precisely determined from the available orbital data.
Habitable zone of AU Mic: 0.265–0.687 AU (conservative: 0.336–0.651 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 ›
Orbit and Year Length
A year on AU Mic d — one full orbit around AU Mic — lasts 12.7 Earth days, shorter than Mercury's 88-day year. Its orbit is nearly circular (eccentricity 0.003).
How Was AU Mic d Discovered?
AU Mic d was discovered in 2023 using the transit timing variations method, with observations from Multiple Observatories.
Transit timing variations reveal a planet through its gravitational tug on a sibling planet, which makes that sibling's transits arrive slightly early or late. The pattern of these deviations betrays the hidden planet's mass and orbit.
How Far Away Is AU Mic d?
AU Mic d is 31.7 light-years (9.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1995. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 557,920 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. AU Mic d scores 0.40, ranking #487 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: AU Mic
AU Mic
- Spectral type
- M1 V
- Surface temperature
- 3,540 K (Sun: 5,772 K)
- Mass
- 0.64 M☉
- Radius
- 0.86 R☉
- Luminosity
- 0.1053 L☉
- Age
- 0.0 billion years (Sun: 4.6)
The AU Mic Planetary System
AU Mic d is one of 4 known planets in the AU Mic system. Its siblings:
AU Mic d — Complete Data
| Mass | 1.05 Earth masses (0.003 Jupiter masses) |
|---|---|
| Orbital period | 12.74 days |
| Eccentricity | 0.003 |
| Earth Similarity Index | 0.40 |
| Distance from Earth | 31.7 light-years (9.7 parsecs) |
| Constellation | Microscopium |
| Discovery method | Transit Timing Variations |
| Discovery facility | Multiple Observatories |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2024-10-03. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About AU Mic d
Is AU Mic d habitable?
AU Mic d is not known to orbit within the habitable zone of AU Mic, and as a terrestrial planet it is an unlikely candidate for life as we know it.
How far away is AU Mic d?
AU Mic d is about 32 light-years from Earth in the constellation Microscopium. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 557,920 years to get there.
How long is a year on AU Mic d?
One orbit around AU Mic takes 12.7 Earth days — short enough that 29 of its years would fit into one Earth year.
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