SIGNS OF LIFE: COULD A SUPERNOVA BE A SIGNAL?

Astronomers think aliens could use supernova explosions to inform us of their presence

- COLIN STUART

Imagine you're an alien on a distant planet and you're desperate to let everyone know you're there. Instead of howling aimlessly into the void, how can you give yourself the best chance of being heard? According to new research, extraterrestrial civilisations could piggyback a signal onto one the brightest beacons in the known Universe: a supernova.

These cataclysmic explosions detonate as the biggest stars die. For a time they shine as brightly as 10 billion Suns and release as much energy as the Sun will emit in its entire 10-billion-year lifetime. When a supernova goes off, astronomers sit up and take notice.

In May this year, astronomers erupted in a flurry of excitement when they spotted the supernova SN 2023ixf detonate in the Pinwheel Galaxy (also known as M101). "It was the closest supernova in a decade," says James Davenport, an assistant professor at the University of Washington. It was bright enough to see with amateur telescopes, even though M101 is 21 million light-years away.