SIGNS OF LIFE

The more planets we find outside our Solar System, the better our chances are of finding life on one of them. But if there really is life out there, how do we spot it?

- by GEORGINA TORBET

The first confirmed detection of an exoplanet, a planet outside our Solar System, came in 1992. We've found a lot more in the years since then. According to NASA, by the end of October 2025, the tally stood at over 6,000. But as astounding as that number may sound, the big question isn't how many exoplanets there are (more than we could ever count); it's how many of them can - or do - support life.

Answering that question is far from simple.

Exoplanets float far away from us, at unfathomably vast distances. Even the closest, the super-Earth Proxima Centauri b, is more than four light-years away (over 37 trillion kilometres or 22 trillion miles). If life is out there, spotting it won't be easy.

But scientists are coming up with new and innovative ways to improve the search. Alongside building bigger, more capable telescopes, they're considering multiple factors in their hunt - from a planet's colour to the combination of gases in its atmosphere, and even evidence of advanced technology.

PURPLE IS THE NEW GREEN

When you imagine a lush planet full of life, one colour springs to mind immediately: green. But recent research suggests that, when we're looking for alien life, we should be searching for other colours too.

Prof Lisa Kaltenegger, an astrophysicist and astrobiologist at Cornell University in the US, has been working to understand what characteristics microbial life might have if it developed on planets with environments unlike Earth's.

Based on her research, the colour she thinks we should be looking for is purple.