Researchers at the University of Southern Queensland (UniSQ) have discovered a potentially habitable planet 150 light-years away, similar in size to Earth and with conditions resembling those of Mars.
Dr Alexander Venner, who conducted the research while undertaking his PhD at UniSQ, led the international research team that identified the candidate planet – named HD 137010 b – using data from NASA's Kepler extended K2 mission captured in 2017.
The new planet is estimated to be only six per cent larger than Earth, with a surface temperature more similar to Mars – potentially below -70 degrees, according to the findings published in The Astrophysical Journal Letters.
The study found that the candidate Earth-sized planet is located near the outer edge of the habitable zone, where liquid water could exist on a planet's surface.
HD 137010 b was spotted when it briefly crossed in front of its star during three months of Kepler observations, leaving only the faintest trace. That clue was detected by a team of amateur 'citizen scientists', including Dr Venner.
"I contributed to this citizen science project called Planet Hunters back when I was in secondary school, and it was a big part of how I got into research," Dr Venner said.
"It was an amazing experience to go back to this work and dig up such an important discovery."
Dr Venner estimates the planet's orbital period is most likely around 355 days – giving it roughly a 50 per cent chance of being in the habitable zone.
"Previous discoveries of Earth-sized planets in habitable zones are mostly around so-called red dwarfs, which are much smaller and dimmer than our Sun," he said.
"Scientists have concerns that these planets might lose their entire atmospheres due to high-energy radiation from their host stars, leaving them uninhabitable to known life.
"In contrast, the host star of HD 137010 b has properties much closer to our Sun, which makes it more likely that the planet could sustain an atmosphere based on current theoretical models.
"If HD 137010 b has an atmosphere like that of Earth or Mars, it is likely to be colder than Antarctica. But a thicker atmosphere could warm the planet enough to allow liquid water, which might be a good environment for life."
Dr Venner added HD 137010 b was the first planet candidate with Earth-like properties to transit a Sun-like star bright enough for substantial follow-up observations.
"While current generations of astronomical instruments cannot fully characterise this newly discovered planet, it could become a prime target for future radial velocity instruments aiming to detect Earth analogues," he said.
"Future space missions designed to directly image Earth-like planets, like the NASA Habitable Worlds Observatory, may also be capable of capturing images of HD 137010 b."
The study, 'A Cool Earth-sized Planet Candidate Transiting a Tenth Magnitude K-dwarf From K2', was co-authored by Dr Alexander Venner, Dr Chelsea Huang, Shishir Dholakia and Professor Robert Wittenmyer from UniSQ and researchers from Harvard University and Smithsonian Institute, University of Oxford, NASA Ames Center, and Brorfelde Observatory (Denmark), along with a network of amateur "citizen scientists" from around the world.
