Epsilon Eridani was the closest star known to host a planet until the unconfirmed discovery of Alpha Centauri Bb. Its age is less than a billion years. Because of its youth, Epsilon Eridani has a more active magnetic field than the present-day Sun. Its stellar wind is 30 times as strong. Its rotation period is 11.2 days at the equator. The star is smaller and less massive than the Sun, and has a lower level of metal elements. It is a main-sequence star of spectral class K2, which means that energy generated at the core through nuclear fusion of hydrogen is emitted from the surface at a temperature of about 5,000 K, giving it an orange hue.