The truth is out there: aliens may have been watching us for 5,000 years, according to new research.
It’s naive to think we’re the only form of intelligent life across the entirety of the cosmos. There must be someone, or something, somewhere out there. It’s likely they don’t know of our existence at all – but what if we have our very own Kang and Kodos keeping their eyes on us?
Since the dawn of civilisation, around 1,715 stars have been in a position to see Earth, with at least 29 potentially habitable worlds orbiting them. They could be looking at us right now, listening to the sounds of our radio stations broadcasting into space – of course, from their point of view, we’re the aliens.
Corresponding author Professor Lisa Kaltenegger, of Cornell University in New York, said: ‘We wanted to know which stars have the right vantage point to see Earth – as it blocks the Sun’s light. And because stars move in our dynamic cosmos, this vantage point is gained and lost.’
Exoplanets, a planet outside our solar system, can be detected by looking for their transiting stars. Earth could be identified using the same method, with possible aliens able to spot the pale blue dot crossing the sun.
Published in Nature and based on data from the European Space Agency’s Gaia satellite that has mapped the Milky Way, the study is said to be the first to consider changing vantage points over time. Over the next 5,000 years, Earth will come into the sight lines of 319 other stars, all within 326 light-years, equating to 1,916,431,926,446,981 miles.
For example, the Trappist-1 system 45 light-years (264,538,149,356,178 miles) away is home to seven rocky and watery Earth-sized planets, four of which are temperate and habitable. This is just one of seven solar systems known to host exoplanets, and each one of these worlds could have an opportunity to find us, the research says.
There’s also the Ross 128 system, with a red dwarf host star located in the Virgo constellation, around 11 light-years (64,664,880,953,732 miles) away. It’s the second closest system with an exoplanet somewhat equatable to Earth, where any inhabitants would have seen us for 2,158 years, before disappearing from view around 900 years ago.
‘Stars with a vantage point from which they could see Earth transit the Sun could be priority targets for searches for potentially habitable planets,’ Prof Kaltenegger said.
Co-author Dr Jackie Faherty, of the American Museum of Natural History in New York, said: ‘Gaia has provided us with a precise map of the Milky Way galaxy. It has allowed us to look backward and forward in time – and to see where stars had been located and where they are going.’
‘Our solar neighbourhood is a dynamic place where stars enter and exit that perfect vantage point to see Earth transit the Sun at a rapid pace,’ she added.
Chemical signatures can be identified from exoplanets hosting intelligent life if they transit or cross their own sun.
Prof Kaltenegger said: ‘Our analysis shows even the closest stars generally spend more than 1,000 years at a vantage point where they can see Earth transit. If we assume the reverse to be true, that provides a healthy timeline for nominal civilisations to identify Earth as an interesting planet.’
The James Webb Space telescope, expected to launch later this year, is set to take a detailed look at several transiting worlds to characterise their atmospheres and search for extra-terrestrial life.
There’s also the ambitious Breakthrough Starshot project, which plans to launch a nano-sized spacecraft at a planet orbiting Proxima Centauri 4.2 light-years (24,690,227,273,243 miles) from us.
Dr Faherty said: ‘One might imagine worlds beyond Earth that have already detected us are making the same plans for our planet and solar system. This catalogue is an intriguing thought experiment for which one of our neighbours might be able to find us.’
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