Astronomers are probing faraway planets with greater sophistication
Aug 3rd 2019IN THE DELUGE of planets found beyond the solar system over the past decade, those of system TOI-270 might not seem special. There are three of them, orbiting a star 73 light-years away. This is neither the closest system known, nor does it contain the most Earthlike exoplanet. It has, though, sent a buzz through astronomy.TOI-270 was discovered earlier this year by the Transiting Exoplanet Survey Satellite, TESS, an American instrument launched in 2018. (TOI stands for TESS object of interest.) Its innermost world is a super-Earth, a rocky planet a little bigger than Earth that scurries around its parent star once every three days. Farther out, at orbits of around six and 11 days, are a pair of larger objects known as mini-Neptunes. Having representatives of these two types of planet in a single system is a valuable find. It should help astronomers understand a bit better how different sorts of planet form.Choose us for news analysis that respects your time and intelligenceSubscribe to The EconomistWe filter out the noise of the daily news cycle and analyse the trends that matterWe give you rigorous, deeply researched and fact-checked journalism. That’s why Americans named us their most trusted news source in 2017Available wherever you are—in print, digital and, uniquely, in audio, fully narrated by professional broadcastersThis website adheres to all nine of NewsGuard‘s standards of credibility and transparency.ORContinue reading this articleRegister with an email address