Earth 2.0? Scientists discover a new planet 40 light-years away that could support human life

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NASA has discovered an Earth-like planet 40 light years away that could be a promising candidate to host human life.

The exoplanet, called Gliese 12 b, is slightly smaller than our planet and has an estimated surface temperature of 107 degrees Fahrenheit - assuming it doesn't have an atmosphere.

Gliese 12 b sits just inward of the habitable zone - the distance from a star at which liquid water could exist on orbiting planets' surfaces.

Astronomers now plan to analyze Gliese 12 b to determine if it does have an Earth-like atmosphere which could reveal if the exoplanet can maintain the right temperature for water to form on its surface - an essential compound to supporting life.

Gliese 12 b has been labeled as the 'nearest, transiting, temperate, Earth-size world to date,' and is a candidate for future exploration by NASA's $9.5 billion James Webb Space Telescope.

An international team of astronomers discovered Gliese 12 b, an exoplanet that is located 40 light years from Earth and has a surface temperature of 107 degrees Fahrenheit. Pictured: Image of Gliese 12 b's location in 1998 (left) and 1949 (right)

An international team of astronomers used NASA's TESS (Transiting Exoplanet Survey Satellite) to narrow down Gliese 12 b's location.

These discoveries are commonly made using the 'transit method' - when the planet crosses in front of its star, causing a drop in its brightness.

During the exoplanet's transit, light from the star passes through it's atmosphere, absorbing some of the wavelengths which releases gas molecules that telescopes, like the James Webb can detect.

The team found that Gliese 12 b has a much tighter orbit than Earth, meaning it crosses its cool red dwarf star, called Gliese 12, more often and completes one orbit every 12.8 days.

'Gliese 12 b represents one of the best targets to study whether Earth-size planets orbiting cool stars can retain their atmospheres, a crucial step to advance our understanding of habitability on planets across our galaxy,' said Shishir Dholakia, a doctoral student at the Centre for Astrophysics at the University of Southern Queensland in Australia.

The exoplanet's distance from its dwarf star is only seven percent of the distance between the earth and the sun, providing it with 1.6 times more energy.

However, Gliese 12 b's habitable conditions depend on whether it has the same type of atmosphere as Earth, making its temperature closer to the average of 59 degrees Fahrenheit found on our planet.

Astronomers have discovered roughly 5,000 exoplanets, but estimate there are likely over a trillion in the Milky Way alone. Pictured: location of Gliese 12 b

'Atmospheres trap heat and - depending on the type - can change the actual surface temperature substantially,' Dholakia explained.

'We are quoting the planet's 'equilibrium temperature', which is the temperature the planet would be if it had no atmosphere.

The team compared Gliese 12 b to Venus, reporting that it is roughly the same size and receives slightly less energy from its star - about 85 percent.

But because Venus doesn't have an atmosphere to block the sun's harmful rays, it developed a greenhouse effect, reaching temperatures of 752 degrees Fahrenheit.

'The Earth is habitable, but Venus is not due to its complete loss of water,' said Larissa Palethorpe, a doctoral student at the University of Edinburgh and University College London.

'Because Gliese 12 b is between Earth and Venus in temperature, its atmosphere could teach us a lot about the habitability pathways planets take as they develop,' she added.

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An important factor for understanding whether the exoplanet could be habitable is looking at the level of storms emitted from its star.

Typically, red dwarf stars are magnetically active which causes them to project frequent X-ray flares that could destroy the atmosphere.

The teams have high hopes that this isn't the case though because the Gliese 12 star hasn't exhibited any signs of extreme storms or behavior.

Astronomers have already discovered roughly 5,000 of these planets, but estimate there are likely over a trillion exoplanets in the Milky Way alone - so far, only a handful are thought to have the environment needed to sustain life.

'We know of only a handful of temperate planets similar to Earth that are both close enough to us and meet other criteria needed for this kind of study,' said Michael McElwain, a research astrophysicist at NASA's Goddard Space Flight Center and a co-author of the Gliese 12 b study.

'To better understand the diversity of atmospheres and evolutionary outcomes for these planets, we need more examples like Gliese 12 b,' he added.