Smallest known exoplanet may be Earth-mass

The smallest planet around a normal star other than the Sun may be even smaller than first thought. A new analysis suggests the rocky body weighs just 1.4 Earths - less than half the original estimate. Observations over the next few months should test the prediction.

Most known "exoplanets" are huge gas giants, hundreds of times Earth's mass, and were discovered by detecting the wobble they induce in their parent stars.

But in 2008, astronomers discovered a planet estimated to weigh just three Earth masses. Called MOA-2007-BLG-192-L b, it claimed the title of the lightest known exoplanet, apart from one tiny world discovered orbiting a dead star called a pulsar.