Less than a year ago, an international team of astronomers put the star TRAPPIST-1 in the news. TRAPPIST-1 itself is unremarkable, belonging to the class of small, dim stars known as “ultracool dwarfs.” Rather, it was the presence of three planets orbiting the star that made the news. While they probably orbit too close to support liquid water, TRAPPIST-1’s proximity to Earth—it’s less than 40 light years away—makes detailed observations of any planetary atmospheres a realistic possibility.

But the orbit of the outermost planet, TRAPPIST-1d, wasn’t well defined by the initial observations, causing its discoverers to go back for some followup observations. Those turned up four more planets, three of which are likely to be in the habitable zone of their host star. As the orbit of the outer one is, once again, uncertain, more observations will undoubtedly be in the works. Who knows what they’ll turn up?

The TRAPPIST family

TRAPPIST-1 got its name from the telescope that first spotted the planets, the Transiting Planets and Planetesimals Small Telescope, although researcher Emmanuël Jehin noted, “By the way, Trappist is the name of a famous Belgian special beer.” It’s a Belgian project that searches nearby dwarf stars for the presence of planets, since the dim star would make observations of planetary atmospheres much easier. The team’s first telescope is based in Chile’s Atacama desert, but it has since added a second in Morocco.