An Update on the Potential Habitability of TRAPPIST-1. No Aliens yet, but We’ve Learned a lot.

An Update on the Potential Habitability of TRAPPIST-1.  No Aliens yet, but We’ve Learned a lot.
read more

One year ago, I wrote an article about the remarkable discovery of the TRAPPIST-1 planetary system, a system of seven temperate terrestrial planets orbiting an ultra-cool red dwarf star. This was an enormous astronomical discovery because these low-mass stars are the most numerous ones in our galaxy, and the discovery of potentially habitable planets around one of them led many people to speculate about the existence of life there and elsewhere in our galaxy around similar stars.

This announcement also inspired a lot of additional studies by astronomers worldwide, who have used additional instruments and run complex models to better understand this planetary system and its potential for hosting life.

One year later, it seems to me that the time is right to give you an update on what we’ve learned about this planetary system, which is located only 41 light-years from Earth.

Wonderful Potentially Habitable Worlds Around TRAPPIST-1

Wonderful Potentially Habitable Worlds Around TRAPPIST-1
read more
PIA21421 small
Abstract Concept of TRAPPIST-1 System credit: NASA/JPL-Caltech

In May 2016, Michael Gillon and his team announced the discovery of three Earth-sized exoplanets around TRAPPIST-1, an ultra cool M-dwarf star, using the small TRAPPIST telescope at ESO-La Silla, Chile. It was an exciting discovery—yet on that day no one could possibly have imagined that less than a year later they would make another significant discovery involving the same system. But here we are: today, they announced in Nature the discovery of seven potentially habitable Earth-like worlds.

The star, named TRAPPIST-1, is a fairly inconspicuous star in our Milky Way. Small (8% the mass of the sun) and cold (half the temperature of the sun), it is a member of an ultra-cool dwarf population that represents 15% of the star population of our galaxy. In 2016, Gillon and his team detected the transit (i.e., the shadow of a planet passing between its host star and us) of three exoplanets at the inner edge of the habitable zone of their star.