Earth Used To Be... Purple?

There’s a real hypothesis that ancient Earth may have looked very PURPLE. It’s no surprise that Earth from millions of years ago looked a lot different from the Earth we see today, but this hypothesis is changing how we think about what distant worlds containing life might look like. Astrobiologists use real science to look at the modern world and imagine alternative realities. That way if we truly find alien life we’ll actually be able to recognize it! #earth #aliens #space #science