Seemingly, everyone’s a bit uncertain about a star named MOA-2007-BLG-192L. It’s known to have a planet in tow, and everyone agrees that it’s a small planet, but exactly how small seems to be a contentious issue.

The planet was originally reported in 2008 as weighing a mere 3.3 Earth masses, making one of the lightest planets discovered. The caveat was that its host star was a feeble brown dwarf. At a distance of around 0.6 AU, that would be a fairly cold planet.

However, New Scientist (amongst others) caused a stir by reporting findings that it’s only a mere 1.4 Earth masses, and that the host star is in fact a red dwarf. That might still be too cold for any prospective life there, but on the other hand, it would be the first planet with an Earth-like mass discovered around a main sequence star*.

As it happens, that might not be entirely accurate. If the star is a red dwarf, then it might be 1.4 Earth masses. For now, I guess, we’ll just have to sit tight and wait for them to confirm the masses of the two objects. Only then will we be able to say if we have indeed found a true terrestrial planet…

Either way, whether it’s 3.3 or 1.4 Earth masses, it’s still an impressively small world to have discovered. Gravitational microlensing is evidently a rather powerful tool in the planet hunters arsenal.

*For the record, much smaller planets (including one that could actually be a comet) have been found around pulsars. For some reason everyone always forgets about those when discussing exoplanets…