K2-121 is 553 light-years from the Sun. The NASA Exoplanet Archive lists 1 planet around this 4,526 K star; the first was found in 2017 by transit (K2).
Fly there in 3DK2-121 b goes round its star every 5.19 days, 17 times as often as Mercury goes round the Sun.
| Surface temperature | 4,526 K |
| Mass | 0.71 solar masses |
| Radius | 0.675 solar radii |
| Luminosity | 0.1798 times the Sun |
| Apparent magnitude | 13.229 |
| Distance from the Sun | 552.5 light-years (169.4 parsecs) |
| Position (J2000) | RA 126.9367°, Dec 17.5793° |
| Constellation | Cancer |
| Planet | Year | Orbit | Radius | Mass | Found |
|---|---|---|---|---|---|
| K2-121 b | 5.19 days | 0.0525 AU | 7.16 R⊕ | 51 M⊕ | Transit, 2017 |
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 4,526 K, 0.18 times as bright as the Sun, the habitable zone, where starlight could keep water liquid on a rocky surface, runs from about 0.43 to 0.79 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 553 years ago, around 1470.