To find others in the universe, we have to think like they would, presuming that they’re also curious about us. Now astronomers have proposed a new game plan that pinpoints a chunk of the cosmos where Earth is most visible to any potential peepers — and the swath is just two-thousandths of the entire sky.
If that sounds too petite, consider this: Planets in their old age don’t produce their own light. To map them, we have to wait until they pass in front of a star and block out some of its light. And when that light dims, sensitive equipment back on our planet detects it. A few crunched numbers later, we identify the size and orbit of the distant land.
But this form of detection, called the transit method, isn’t as easy as it sounds. Distances to other planets are so vast, NASA’s Jet Propulsion Laboratory likens it to standing in Boston and trying to see a moth in a spotlight in — you might need to squint — San Diego. To date, scientists have confirmed nearly 2,000 exoplanets, or planets that aren’t in our solar system, with thousands of candidates still waiting to be accepted.
If you’re an inquisitive life form on an exoplanet, your googly eyes glued to your sky, that means you could use a similar method to see Earth. That’s essentially the strategy that researchers have proposed to overhear aliens, the Max Planck Institute in Germany announced earlier this month. The region that could see Earth’s transit zone in front of the sun is narrow, but it could be a fruitful point for astronomers to focus on in the future, in case extraterrestrials have seen Earth (the moth) in the sun (the spotlight).