About this world
MOA-2011-BLG-291L b is a Neptune-like planet orbiting MOA-2011-BLG-291L, a star 14.4 thousand light-years from Earth. It is about 4.4 times the size of Earth (its size estimated from its mass) and holds 18 Earth masses.
At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2018 by microlensing with MOA. A foreground star's gravity magnifies a background star; a planet adds a blip.