Astronomers have found strong evidence of a giant gas planet orbiting a star in a solar system close to our own sun.
Four light-years away from Earth, the Alpha Centauri triple-star system has long been a compelling target for scientists to search for worlds outside our solar system. Now, scientists have found a lifeless planet which could be a close neighbour to Earth in astronomical terms, and could even have moons that sustain life.
The potential planet, detected last year, disappeared in follow-up observations. But astronomers found new signs using NASA’s powerful James Webb Space Telescope.
If confirmed, the planet would be the closest to Earth that orbits in the habitable zone of a sun-like star.
“Four years is a long way but in galaxy terms, it’s very close – it’s in our neighbourhood,” Dr Carly Howett, associate professor of space instrumentation at the University of Oxford, told the BBC.
“It is around a star that is sun-like and about the same temperature and brightness. That’s really important if we want to think about habitable worlds.”
However, because the planet candidate is a gas giant, scientists say it would not support life as we know it.
Charles Beichman, from NASA’s Jet Propulsion Laboratory and the NASA Exoplanet Science Institute at Caltech’s IPAC astronomy center, said: “With this system being so close to us, any exoplanets found would offer our best opportunity to collect data on planetary systems other than our own.
“Yet, these are incredibly challenging observations to make, even with the world’s most powerful space telescope, because these stars are so bright, close, and move across the sky quickly,” he added.
The stars create huge amounts of bright light which can block out nearby objects, which might explain why the potential planet appeared to disappear.
Mr Beichman added: “Webb was designed and optimised to find the most distant galaxies in the universe. The operations team at the Space Telescope Science Institute had to come up with a custom observing sequence just for this target, and their extra effort paid off spectacularly.”
Confirmation of the potential planet would mark a new milestone for exoplanet imaging efforts, as it would be the closest to its star to be seen so far.
“It’s also the most similar in temperature and age to the giant planets in our solar system, and nearest to our home, Earth,” said PhD student Aniket Sanghi of Caltech, a co-first author on the two papers covering the team’s research. “Its very existence in a system of two closely separated stars would challenge our understanding of how planets form, survive, and evolve in chaotic environments.”
Astronomers hope to use a new telescope, NASA’s Nancy Grace Roman Space Telescope, which is set to launch by May 2027, equipped with dedicated hardware to test new technologies in the search for new life.
