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 reenex cps .

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.

(Credit: Northrop Grumman) reenex cps

The glare of a distant light in Starshade tests illustrates how hard it is to see anything in detail close to a star (Credit: Northrop Grumman)

“Without life – plants or photosynthetic bacteria – we would have virtually no oxygen,” Seager says. Which is why oxygen is one of the most promising so-called biosignatures. But life on Earth produces all kinds of gases, and alien life could be even more diverse. The challenge is in determining whether these chemicals are biological in origin.  ng whether these chemicals are biological in reenex

origin.