OGLE-2005-BLG-390Lb (known sometimes as Hoth by NASA[1]) is a super-Earth ice exoplanet orbiting OGLE-2005-BLG-390L, a star 21,500 ± 3,300 light-years (6,600 ± 1,000 parsecs) from Earth near the center of the Milky Way, making it one of the most distant planets known.

Prior to this, "small" exoplanets such as Gliese 876 d, which has an orbital period of less than 2 Earth-days, were detected very close to their stars.

At the time of discovery, with 5.5 Earth masses, the planet was less massive than the previous candidate for lowest-mass exoplanet around a main-sequence star, the 7.5 Earth mass Gliese 876 d. Since 2013, many Earth-sized or smaller planets around main-sequence stars have been detected by the Kepler spacecraft and others.

[4] OGLE-2005-BLG-390Lb's signature was first detected on January 25, 2006, by observations at the Danish 1.54-m telescope at ESO La Silla Observatory in Chile.

The PLANET/RoboNet campaign regularly investigates promising microlensing event alerts that are issued by the Polish OGLE or the Japanese–New Zealand MOA survey.

[6] The PLANET team conducted close observation of the OGLE-2005-BLG-390 microlensing event over a period of about two weeks.

[2] The paper submitted to Nature bears the names of all members of PLANET, RoboNet, OGLE, and MOA.