ET phone home: Have we found extra-terrestrial life?

Back in February, we heard the news of the discovery of “7 earth-like planets” with claims that these planets can support life. So what makes these planets different from the other countless planets and star-systems forming our universe? As a biologist, I was determined to come out of my comfort zone and find out!

The Discovery

The TRAPPIST-1 System with its seven planets.

At its core, the discovery is that we have found seven planets in a single solar system that we believe have the ability to support life; either our own or extra-terrestrial. This system of planets, known as exoplanets as they are outside our solar system, has been named TRAPPIST-1 with each of the seven planets being named TRAPPIST-1b to TRAPPIST-1h with its star, TRAPPIST-1a, being found in the centre. TRAPPIST-1 is 40-light-years away from earth, equivalent of 235 trillion miles, and is found in the constellation of Aquarius, ‘The Water-Bearer’

Aq Const
The constellation of ‘Aquarius’, known as ‘The Water-Bearer’


Ultra-Cool Stars!!

Cool Star
These stars are ULTRA-COOL!!!

While these planets have been described as ‘earth-like’, the TRAPPIST-1 system as a whole is different to our own solar system in a variety of different aspects. Starting with the central star, TRAPPIST-1a is different type star compared to our sun and is classed as an ‘Ultra-Cool Star’. This means that it is smaller and cooler than our sun. In fact, TRAPPIST-1a is only 8% of the mass of our sun and is only slightly larger than the size of Jupiter. By comparison you would need around 1000 Jupiters to recreate the size and mass of our sun! Ultra-Cool stars are also around half the temperature of our sun. Now while TRAPPIST-1a’s 2300°C temperature may not exactly seem cold, it is nothing compared to our sun’s 5500°C temperature.  Because of its small size and lower temperature, it does not give out as much energy and is therefore much harder to find than other stars. However, it is because of these features that scientists believe that Ultra-Cool Stars are the best place to look for life outside of our solar system.

Jupiter Sun
Our Sun and the planets in our solar-system. TRAPPIST-1a is only the size of Jupiter for comparison!

The search for life

Is there life on other planets? Are we alone in the universe? These kind of questions have plagued scientists for generations as we searched the stars. The way scientists predict whether a planet can sustain life is whether liquid water can be found there. Liquid water is essential for life, as we currently understand it, to exist.  It is believed that all seven of the planets may have water, and therefore be able to support life, but three have been singled out as more likely than the others. This is because they are found in the star’s ‘habitable zone’ which is the area around the star that’s at the correct temperature to have water in its liquid state. This area is also lovingly called ‘The Goldelocks Zone’ as the temperature is ‘not too hot, not too cold but just right’!

Habitable Zones
Comparison of the TRAPPIST-1 habitable zone and our solar system’s habitable zone. All of the TRAPPIST-1 planets are closer to their sun than Mercury is to out sun!

‘7 names for 7 planets’

NASA asked Twitter to name the series of planets and the internet had a field day (I guess some people will never learn from Boaty McBoatface!). I’ve included some of my favourites but if you want to look further into some of the suggestions, search for the hashtag ‘#7NamesFor7NewPlanets’. Click the images below to enlarge them.

If you want some more information about the TRAPPIST-1 system then visit, a website set-up and run by a group of the researchers.  As I said earlier, talking about life in space was a little out of my comfort zone, and I shall be going back to human biology for the next post! However, personally I found this topic really interesting to research so hopefully I’ll come back to space later in the future!