Aliens could be living on planet dubbed ‘Earth’s next-door neighbour’

Aliens could call a planet about a 282 million-year drive away home, scientists say.

GJ 3378b is an exoplanet – a planet not inside our solar system – that is more than double the size of Earth.

It’s 25 light-years away from us, so it would take you 141 million years on a bullet train to get there, according to Nasa’s Exoplanet Catalog.

Astronomers at the University of California, Irvine, have found that GJ 3378b’s atmosphere could be the right thickness for life to survive.

Paul Robertson, UC Irvine associate professor of astronomy and lead author, said: ‘This one’s exciting.

‘It’s one of our closest cosmic neighbours. 25 light-years sounds like a long way, but the Milky Way is about 100,000 light-years across, so in that respect it’s our next-door neighbour.’

GJ 3378b is ‘exciting’ because it sits in the so-called ‘Goldilocks zone’ that Earth is also in – not too hot, not too cold, so liquid water could be on it, according to findings published in The Astrophysical Journal.

The rocky world is snuggled up to a red dwarf star, much dimmer and cooler than the Sun, with a year being just 21.5 days.

‘This super-Earth gets about 90% of the radiation from its host star as Earth gets from its sun, so it’s right in the sweet spot,’ added Robertson.

If it were even just a little farther away from this spot, called the cosmic shoreline, the star’s radiation would peel away the planet’s atmosphere.

This was the case for Mars, for example, which experts suspect may have once had a cosy, Earth-like atmosphere before the Sun stripped it bare.

Robertson said: ‘If you scale the Earth down to the size of an apple, its atmosphere would be about as thick as the skin of the apple.

‘That’s just enough to maintain the kinds of surface pressures where you can have liquid water. It’s enough that there’ll be breathable air and it provides maybe a little bit of protection from the harsh radiation environment of space.’

Robertson stressed that they don’t know for sure if GJ 3378b has an atmosphere, but it is a promising candidate for otherworldly life.

They made the discovery using the Habitable-zone Planet Finder on the Hobby-Eberly Telescope in Texas and Arizona’s NEID Spectrometer on the WIYN Telescope.

Could life be elsewhere?

So far, Earth remains the only planet in the universe where life is known to exist – yet more than 6,000 exoplanets have been discovered so far.

Figuring out if one of these far-flung planets has an atmosphere that is friendly to life is easier than you’d think – well, kind of.

As an exoplanet passes in front of its host star, its atmosphere lights up. Gases swirling above change the colour of the starlight beamed to Earth.

They try to see if there are any biosignatures – a signal of life – inside the atmosphere, like oxygen or other gases only made by living organisms, Lisa Kaltenegger, the director of the Carl Sagan Institute at Cornell University, told Metro.

‘Signs of life are written in a planet’s light – if you know how to read it,’ Kaltenegger said.

Kaltenegger and her team compiled a list in March of 45 ‘Earth-like’ planets that could be home to extraterrestrial life. Maybe.

‘What makes a planet habitable? Being a rock and having liquid water on the surface is a great start,’ she said.

‘Whether there is life there is an open question, but that is why it is so exciting to live in this time of golden exploration, where we can find out.’

For now, Earth’s inhabitants remain alone in the cosmos. But this being our only definition of life could be a problem, Kaltenegger wondered.

We’re only really looking for the kind of oxygen-breathing, water-guzzling life that could survive on Earth.

‘Life on other worlds could be very different from Earth,’ Kaltenegger said, adding: ‘If the planet is not much hotter or much colder (if water evaporates or freezes completely) then you need another solvent for life.

‘We hope that the methane and ethane lakes on Saturn’s moon Titan could also allow for life, but we don’t know that yet.’

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