LHS 1140 b was discovered in 2017 by which ground-based exoplanet survey?

LHS 1140 b was discovered in 2017 by the MEarth Project, a ground-based survey designed to find transiting planets around nearby, small stars. The project’s MEarth-South telescopes detected the planet as it passed in front of its dim red-dwarf host.

The transit caused a tiny, repeatable decrease in the star’s brightness. Follow-up observations, including radial-velocity measurements, helped confirm that the signal came from a planet rather than stellar activity or an unrelated eclipsing object. The discovery was announced in April 2017 and made LHS 1140 b an important target for atmospheric studies.

LHS 1140 b is a super-Earth orbiting within its star’s conservative habitable zone. It is about 5.6 times Earth’s mass, roughly 1.7 times Earth’s radius, and completes an orbit in about 24.7 days. Those figures can create quiz confusion: 24.7 days is the planet’s orbital period, whereas MEarth Project is the discovery survey. HATNet, KELT, and SuperWASP are also ground-based transit surveys, but they did not discover this particular world.