About this world
47 UMa b is a gas giant orbiting 47 UMa, a yellow, Sun-like star (type G0V) 45 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 2.5 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 2.95 years at 2.1 AU from its star.
Its equilibrium temperature is about 215 K (−58 °C), which places it in the optimistic habitable zone: the band where liquid water could exist on a rocky surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 1996 by radial velocity with Lick Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. 47 UMa has 3 known planets; the others are 47 UMa c and 47 UMa d.