An international team of researchers discovered three potentially habitable exoplanets orbiting a cold dwarf star 40 light-years away from Earth. Using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST), the researchers’ study published on May 2 in the journal Nature states that the objects’ sizes are similar to that of Earth and Venus.

The two innermost planets will orbit the Jupiter-sized 2MASS J23062928-0502285 star currently known as TRAPPIST-1 in 1.5 and 2.4 days. The third one may orbit the star from four to 73 days.

The two innermost planets receive more radiation as the Earth gets from the sun, one quadruple that amount and another twice the amount of radiation. On the other hand, the third planet gets less radiation than Earth. Overall, these planets’ temperature is believed to be below 400 Kelvin (126.85 degrees Celsius).


This artist’s impression shows an imagined view from the surface one of the three planets orbiting an ultracool dwarf star just 40 light-years from Earth that were discovered using the TRAPPIST telescope at ESO’s La Silla Observatory. These worlds have sizes and temperatures similar to those of Venus and Earth and are the best targets found so far for the search for life outside the solar system. They are the first planets ever discovered around such a tiny and dim star. Credit: ESO/M. Kornmesser

The team believes that all of these three planets are tidally locked, meaning their orbital period matches their rotational period. While the two innermost planets may have day sides that are too hot and night sides that are too cold, an area on the western side of each planet that is not too cold and receives just enough daylight may be the habitable zone.

However, the researchers believe that the third planet may be within the habitable zone. Still, study co-author Julien de Wit, a postdoctoral researcher in the Department of Earth, Atmospheric, and Planetary Sciences at MIT, says that further studies are needed to assess the planets’ atmospheres and capability to support life.

“Now we have to investigate if they’re habitable,” de Wit says. “We will investigate what kind of atmosphere they have, and then will search for biomarkers and signs of life. We have facilities all over the globe and in space that are helping us, working from UV to radio, in all different wavelengths to tell us everything we want to know about this system. So many people will get to play with this [system].”