Scientists are getting better at characterizing exoplanets, and that's leading to some surprising discoveries. As Reuters reports, a DLR-led team has determined that the relatively nearby (31 light-years) planet GJ 367b is significantly smaller than Earth at 5,592 miles across, but is more dense than Earth - it's about as dense as iron, and 86 percent of the planet is made from the metal. The planet more closely resembles Mercury than humanity's homeworld.
GJ 367b certainly isn't habitable. It's so close to its host red dwarf star that an orbit takes just 7.7 hours, and the radiation is so intense that it could reach up to 2,732 degrees Fahrenheit. That's enough to melt any metals and rocks, and certainly wouldn't allow for life as we know it. It's safe to presume there won't be any colonization missions as a result.
The assessment by itself is notable, however. GJ 367b is the smallest planet ever characterized to this level of detail, and that could help in the search for more habitable exoplanets, understanding planet formation and even gauging the criteria for habitability. Those, in turn, could help astronomers determine whether or not the relatively life-friendly Solar System is as rare as it seems.