Kepler-399 is 2,415 light-years from the Sun. The NASA Exoplanet Archive lists 3 planets around this 5,502 K star; the first was found in 2014 by transit (Kepler).
Fly there in 3DKepler-399 b goes round its star every 14.4 days, 6 times as often as Mercury goes round the Sun.
| Surface temperature | 5,502 K |
| Mass | 0.902 solar masses |
| Radius | 0.68 solar radii |
| Luminosity | 0.3819 times the Sun |
| Apparent magnitude | 14.686 |
| Age | about 3.98 billion years |
| Distance from the Sun | 2415.3 light-years (740.5 parsecs) |
| Position (J2000) | RA 299.5017°, Dec 40.6708° |
| Constellation | Cygnus |
| Planet | Year | Orbit | Radius | Mass | Found |
|---|---|---|---|---|---|
| Kepler-399 b | 14.4 days | 0.103 AU | 0.96 R⊕ | 0.84 M⊕ estimated | Transit, 2014 |
| Kepler-399 c | 26.7 days | 0.155 AU | 1.43 R⊕ | 2.63 M⊕ estimated | Transit, 2014 |
| Kepler-399 d | 58.0 days | 0.261 AU | 1.89 R⊕ | 4.23 M⊕ estimated | Transit, 2014 |
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 5,502 K, 0.38 times as bright as the Sun, the habitable zone, where starlight could keep water liquid on a rocky surface, runs from about 0.60 to 1.06 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 2,415 years ago, around 400 BC.