“If we want to find a true Earth twin in the near future – like in the next decade or two – then yes, we definitely need to do the Starshade,” says Seager, who is based at Massachusetts Institute of Technology (MIT).

That’s because a Sun-like star is 10 billion times brighter than an Earth-sized planet. The only hope astronomers have for glimpsing any hint of life – likely some form of microorganism – would be to somehow block the light from such a star, allowing a telescope to directly observe the planet itself. It’s a strategy radically different from the main way astronomers have discovered and studied planets so far.



Because planets are so distant, small, and faint, astronomers have mostly probed them indirectly – for example by detecting dips in starlight when a planet passes in front of its star or by measuring how the star wobbles when a planet’s gravity tugs on it. But alien-hunting demands a new tactic.

Scientists hope to identify the gases in the planet’s atmosphere, and detect chemicals that suggest the presence of life – chemicals like oxygen, which comprises 20% of Earth's atmosphere.