13point8100 ly map
4 known planets · 31.7 light years

AU Microscopii

AU Microscopii is a red dwarf (M1 V) 31.7 light years away, with 4 confirmed planets. Distances and orbital speeds are to scale; the star and planets are enlarged so you can see them.

Day 0
habitable zone (estimate)planet orbits

Green band: where liquid water could exist on a planet's surface. Drag to turn the system, pinch or scroll to zoom.

The star

The star

AU Microscopii

Type
M1 V
Surface
≈ 3,540 K
Size
0.86 × the Sun
Mass
0.64 × the Sun
Brightness
0.105 × the Sun
Habitable zone
0.308–0.542 AU

The planets

AU Microscopii

AU Mic b

Year
8.46 days
Distance from star
0.07 AU
Mass
9 Earths
Size
4.8 × Earth
Temperature
≈ 555 K (+282 °C)
Found
2020, transit (Transiting Exoplanet Survey Satellite (TESS))
Too hot
AU Microscopii

AU Mic c

Year
18.86 days
Distance from star
0.119 AU
Mass
14 Earths
Size
2.8 × Earth
Temperature
≈ 425 K (+152 °C)
Found
2021, transit (Transiting Exoplanet Survey Satellite (TESS))
Too hot
AU Microscopii

AU Mic d

Year
12.74 days
Distance from star
0.0917 AU
Mass
1.1 Earths
Size
1 × Earth
Found
2023, transit timing variations (Multiple Observatories)
Outside the habitable zone
AU Microscopii

AU Mic e

Year
33.11 days
Distance from star
0.173 AU
Mass
21 Earths
Size
4.9 × Earth
Found
2025, radial velocity (Mauna Kea Observatory)
Outside the habitable zone

Masses found by the wobble method are minimums, because the orbit's tilt is unknown. Temperatures are equilibrium estimates for a bare planet, before any atmosphere.

How we know

The wobble

The planet tugs its star back and forth. Spectrographs measure the tiny shift in the star's light, which gives the planet's year and a minimum mass.

The shadow

The planet passes in front of its star and dims it by a fraction of a percent, every orbit. The dip gives the planet's size and year.

Early and late

A known planet arrives early or late for its transits, betraying the pull of another, unseen planet.

Sources

  1. Planet and star parameters: NASA Exoplanet Archive, Planetary Systems Composite Parameters, retrieved 31 Oct 2026. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program.
  2. Position: HYG Database v4.1 (CC BY-SA 4.0).
  3. Habitable zone: a simple estimate from the star's brightness (√L × 0.95 to 1.67 AU), shown as a guide.
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