Kepler-257 is 2,545 light-years from the Sun. The NASA Exoplanet Archive lists 3 planets around this 5,180 K star; the first was found in 2014 by transit (Kepler).
Fly there in 3DKepler-257 b goes round its star every 2.38 days, 37 times as often as Mercury goes round the Sun.
| Surface temperature | 5,180 K |
| Mass | 0.916 solar masses |
| Radius | 1.037 solar radii |
| Luminosity | 0.4192 times the Sun |
| Apparent magnitude | 15.652 |
| Age | about 1.48 billion years |
| Distance from the Sun | 2544.9 light-years (780.3 parsecs) |
| Position (J2000) | RA 297.3160°, Dec 46.0233° |
| Constellation | Cygnus |
| Planet | Year | Orbit | Radius | Mass | Found |
|---|---|---|---|---|---|
| Kepler-257 b | 2.38 days | 0.0340 AU | 2.61 R⊕ | 7.32 M⊕ estimated | Transit, 2014 |
| Kepler-257 c | 6.58 days | 0.0660 AU | 5.41 R⊕ | 25.2 M⊕ estimated | Transit, 2014 |
| Kepler-257 d | 24.7 days | 0.160 AU | 4.95 R⊕ | 21.7 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.