A renewed dream of life beyond Earth
The discovery of seven Earth-sized – maybe even Earth-like – exoplanets sparks fresh debate about whether we are alone in the universe
Of course, we shouldn’t sensationalise, and the findings need to be put into context. The three inner planets are likely to be too hot, and the outer planet is probably too cold. However, the three in the middle might be just right to harbour liquid water even on the surface, given sufficient atmospheric pressure.
It’s not the first time scientists have discovered so many exoplanets. Of the 3,449 planets identified so far from star systems beyond our own, some of them may harbour the biochemical essentials of life. There are probably many more like them out there.
With the latest news, we have, of course, not discovered a cousin of Earth, let alone seven of them. Nor have astronomers discovered life on any of them. What the Dutch-led multinational team has found is a planetary system with a star called Trappist-1 – also known as an ultra-cool dwarf star – that is not as hot or massive as our sun. This enables the researchers to turn their telescopes to study the planets in great detail without being dazzled as they would be if they were looking at much brighter and more massive stars. This is because those planets block much more light when they pass between their dwarf star and our Earth than would be the case with a more massive and much brighter star like our sun.