DID LIFE COME FROM COMETS?
In the void between planets, huge snowballs tumble across the Solar System. These comets – relics from an age before large worlds circled the Sun – have been patrolling our local neighbourhood for 4.6 billion years. Hidden away in their icy layers are clues to what our Solar System was like all that time ago, along with teasers as to how our family of planets formed. But their real bounty could be knowledge of how one of the Solar System’s stand-out features came to pass: life. Could comets have played a role in delivering biology to Earth? Scientists are starting to think so.
Perhaps the single biggest factor in our planet’s suitability for life is the presence of water. Thanks to our temperate position around the Sun, water can exist largely in liquid form. Yet still fresh from the violent collisions that gave birth to it, the early Earth would have been too hot for any water molecules to escape evaporation. “The impact that formed the Moon would have gotten
