K2-398 is 1,980 light-years from the Sun. The NASA Exoplanet Archive lists 2 planets around this G2 star; the first was found in 2022 by transit (K2).
Fly there in 3DK2-398 b goes round its star every 6.39 days, 14 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.
| Spectral type | G2 |
| Surface temperature | 5,946 K |
| Mass | 0.945 solar masses |
| Radius | 1.239 solar radii |
| Luminosity | 1.818 times the Sun |
| Apparent magnitude | 13.287 |
| Distance from the Sun | 1979.7 light-years (607.0 parsecs) |
| Position (J2000) | RA 161.7350°, Dec 1.9367° |
| Constellation | Sextans |
| Planet | Year | Orbit | Radius | Mass | Found |
|---|---|---|---|---|---|
| K2-398 b | 6.39 days | 0.0662 AU from Kepler’s law | 2.274 R⊕ | 5.79 M⊕ estimated | Transit, 2022 |
| K2-398 c | 18.8 days | 0.136 AU from Kepler’s law | 5.098 R⊕ | 22.8 M⊕ estimated | Transit, 2022 |
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 5,946 K, 1.8 times as bright as the Sun, the habitable zone, where starlight could keep water liquid on a rocky surface, runs from about 1.27 to 2.23 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 1,980 years ago, around AD 50.