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All the life we know of in the entire universe is squeezed onto a tiny rock, floating in a minor arm of the Milky Way. There are billions of other planets with the potential to support life. But what effect does our location have on the prospect of finding it?
So far, our search for life elsewhere has only scratched the surface. “The bubble of space that we’ve managed to search around our sun is very small compared to the size of the galaxy,” says Jessie Christiansen, an astrophysicist at the California Institute of Technology. Yet we have already found more than 5000 planets circling other stars, called exoplanets. While some of these have been detected across our galaxy – and even in other galaxies – most reside within a few hundred light years of our sun, a stone’s throw in the cosmic scheme of things.
Our galactic neighbourhood
Astronomers have begun looking at different types of stars in our galactic neighbourhood to see how they might affect the chances of habitability on the planets around them. We live in an arm of the Milky Way called Orion, which sits inside the main plane of the galaxy, called the thin disc. We are surrounded by stars within the Orion arm. Further out, on one side we have the overcrowded bulge of the galaxy’s dense core, while on the other we are enveloped by the sparser outer parts of the galaxy’s other arms.
Thin disc stars, like our sun and others in the Orion arm, are generally…
