Astronomers have discovered a potentially habitable new planet about 146 light-years away which is Earth-sized and has conditions similar to Mars.
The candidate planet, named HD 137010 b, orbits a sun-like star and is estimated to be 6% larger than Earth.
An international team of scientists in Australia, the UK, the US and Denmark identified the planet using data captured in 2017 by the Nasa Kepler space telescope’s extended mission, known as K2.
Dr Chelsea Huang, a researcher at the University of Southern Queensland (USQ) in Australia, said the planet has an orbit similar to Earth’s, of about 355 days.
The researchers believe the planet has “about a 50% chance of residing in the habitable zone” of the star it orbits.
“What’s very exciting about this particular Earth-sized planet is that its star is only [about] 150 light-years away from our solar system,” said Huang, one of the co-authors of the research.
“The next best planet around a sun-like star, in a habitable zone, [Kepler-186f] is about four times farther away and 20 times fainter.”
Dr Alexander Venner led the international team who discovered HD 137010 b. Photograph: UniSQ/University of Southern Queensland
HD 137010 b was spotted when it briefly crossed in front of its star, resulting in a minute dimming event.
That faint signal was initially detected by a team of citizen scientists – including the study’s first author, Dr Alexander Venner, when he was still a high school student.
“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,” said Venner, who went on to complete a PhD at USQ.
“It was an amazing experience to go back to this work and dig up such an important discovery.”
The team’s first reaction to the discovery was “that this cannot possibly be true”, Huang said. “But we double checked and triple checked everything and … it’s a textbook example of a transit of a planet.”
The brightness and closeness of the star it orbits puts it “within reach of [being observed with] the next generation of telescopes”, Huang said. “I’m sure this will be the first target to be observed when the technology gets there.”
The star that HD 137010 b orbits around is cooler and dimmer than our sun, meaning that planet’s surface temperature is more similar to Mars, and could be potentially below -70C.
A size comparison of HD 137010 b alongside Earth and Mars. Photograph: NASA/JPL-Caltech/K. Miller (Caltech/IPAC)
Dr Sara Webb, an astrophysicist at Swinburne University who was not involved in the research, said the discovery was “very exciting” but that more results were needed to classify the candidate planet as a confirmed exoplanet.
“There is only one transit [detected], and typically in planetary science we’re talking a gold standard of three [detections].”
That the planet is Earth-like is one exciting possibility, but Webb said it could also “be something called a super snowball. Essentially, a big, icy world that potentially has a lot of water, but a lot of it’s frozen.”
Though the planet “is very close in the grand scheme of our galaxy”, Webb said “if we were to try and get there, it would take us tens of thousands, if not hundreds of thousands of years travelling at the current speeds that we can”.
The research was published in Astrophysical Journal Letters this week.
