K2-172 is 815 light-years from the Sun. The NASA Exoplanet Archive lists 2 planets around this 5,569 K star; the first was found in 2018 by transit (K2).
Fly there in 3DK2-172 b goes round its star every 14.3 days, 6 times as often as Mercury goes round the Sun.
Where the archive gives only a period or only an orbit size, the other is worked out from Kepler’s third law with the star’s mass.
| Surface temperature | 5,569 K |
| Mass | 0.934356 solar masses |
| Radius | 0.868889 solar radii |
| Luminosity | 0.6278 times the Sun |
| Apparent magnitude | 12.5 |
| Distance from the Sun | 814.5 light-years (249.7 parsecs) |
| Position (J2000) | RA 335.3081°, Dec -12.5570° |
| Constellation | Aquarius |
| Planet | Year | Orbit | Radius | Mass | Found |
|---|---|---|---|---|---|
| K2-172 b | 14.3 days | 0.113 AU from Kepler’s law | 1.6661 R⊕ | 3.42 M⊕ estimated | Transit, 2018 |
| K2-172 c | 29.6 days | 0.183 AU from Kepler’s law | 3.2057 R⊕ | 10.4 M⊕ estimated | Transit, 2018 |
Values are the NASA Exoplanet Archive’s composite parameters. A radius marked estimated comes from a mass–radius relation; a mass marked minimum is M sin i. Planet sizes and colours in the 3D view are renderings: none of these worlds has been photographed as more than a point of light.
For a star of 5,569 K, 0.63 times as bright as the Sun, the habitable zone, where starlight could keep water liquid on a rocky surface, runs from about 0.76 to 1.35 AU. None of its known planets orbits inside it. The zone says how much starlight arrives, not whether a planet has water or air. The edges follow Kopparapu et al. (2014), as the 3D view draws them.
The light you see left 815 years ago, around 1210.