The WASP-21 system contains 1 exoplanet. It is located 842.87 light years away from the solar system.
| Mass | 1.01 solar masses |
| Radius | 1.06 solar radiae |
| Temperature | 5800 kelvin |
| Stellar Metallicity | -0.22 decimal exponent |
| Age | 12 billion years |
At more than 50 Earth masses, WASP-21 b is a gas giant, a planet whose mass is mostly made up of hydrogen and helium, like Jupiter and Saturn.
| Mass | 95.345 Earth masses |
| Density | 0.320 grams per cubic centimeter |
| Radius | 11.990 Earth radiae |
| Semi-major Axis | 0.052 AU |
| Eccentricity | 0 |
| Orbital Period | 4.322 days |
| Discovery Method | Transit |
| Discovery Facility | SuperWASP |
| Discovery Telescope | Canon 200mm f/1.8L |
| Discovery Instrument | iKon-L CCD Camera |
| Discovery Date | 2010-09 |
| Reference | Bouchy et al. 2010 |