The first exoplanet was spotted in 1988. Since then more than 3,000 planets have been found outside our solar system, and it’s thought that around 20 percent of Sun-like stars have an Earth-like planet in their habitable zones. We don’t yet know if any of these host life – and we don’t know how life begins. But even if life does begin, would it survive?
Earth has undergone at least five mass extinctions in its history. It’s long been thought that an asteroid impact ended the dinosaurs. As a species, we are rightly concerned about events that could lead to our own elimination – climate change, nuclear war or disease could wipe us out. So it’s natural to wonder what it would take to eliminate all life on a planet.
