When we look for alien solar systems, we tend to look for planets and stars that resemble ones we’re familiar with, including Earth-like planets and sun-like stars. Thanks to the HARPS telescope in Chile, the European Southern Observatory (ESO) not only discovered a star that could be our sun’s twin in a star cluster, but we’ve also found three planets close to it.
The star cluster in question is Messier 67. What’s important here is that these three new planets reside in a star cluster, something that's rare. And this star cluster also contains our solar twin, a star that resembles our sun in almost every way: it has almost the same mass, temperature, and chemical composition. Obviously, such stars, as far as we know, are rare. But that’s not all astronomers discovered: this twin to our sun resides in a cluster with two other stars and has at least three nearby planets. Two of those planets are about the size of Jupiter, with the other being slightly larger. These observations mark the first time that we’ve seen a star cluster with a solar twin that also has planets. In Messier 67’s configuration, the stars and planets orbit around the larger star, that which is our sun’s twin.
Unfortunately, these new planets are probably not habitable. They are extremely hot and do not fall in what we define as the “habitable zone,” a place in orbit where a planet can exist with liquid water. Studying them, though, may still tell us more about our own solar system, particularly if these are planets that might have once resided in the habitable zone and slowly moved out of it (something that occurs naturally over billions of years).