About this world
KMT-2017-BLG-0428L b is a sub-Neptune orbiting KMT-2017-BLG-0428L, a star 17.6 thousand light-years from Earth. It is about 2.2 times the size of Earth (its size estimated from its mass) and holds 5.6 Earth masses.
At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2023 by microlensing with KMTNet. A foreground star's gravity magnifies a background star; a planet adds a blip.