How old is our planet?

Julia Ravey asked University of Bristol researcher Hannah Wakeford about giving planets an age...

Hannah - That's a really good question. And that's actually a really difficult thing for us to do, but when we're looking at alien planets, we can guess how old they are roughly by looking at how old their star is. So if we know how old their star is, then we kind of assume that the planet is somewhere around that time. On Earth, we actually use rocks to determine how old our planet is. And we compare that to meteorites that fall on the Earth. Meteorites that come from space and they are showing us the building blocks of our solar system. So if we can compare the ages of those rocks, we can work out how old our planet is.