A blazing gas giant shrouded in dusty red clouds has been revealed in unprecedented observations of a planet beyond our solar system.
The observations, which astronomers say marked a “historic moment for astronomy,” are the first direct images of a planet outside our solar system by NASA’s $10 billion (£8.65 billion) James Webb space telescope. They are also the first images of an exoplanet using infrared light, which will provide a much more accurate indication of a planet’s mass and temperature and will allow astronomers to detect the movement of clouds drifting across the planet’s sky.
“This is truly a historic moment for astronomy,” said Prof. Sasha Hinkley, an astronomer at the University of Exeter who led the observations. “James Webb is going to open the door to a whole new class of planets that have been completely beyond our reach, and by observing them at a wide range of wavelengths, we can study their compositions in a much more profound way.
“We will be able to detect the presence of the weather.”
Imaging exoplanets directly is a huge technical challenge because the host star is so much brighter. The focus of the latest observations, HIP 65426 b, is a gas giant about five to 10 times the mass of Jupiter, located 385 light-years from Earth in the constellation Centaurus.
It is about 100 times farther from its parent star than Earth is from the sun, making it easier to distinguish. But is still more than 10,000 times fainter than its host star — the equivalent of trying to spot a firefly next to a large lighthouse more than 80 miles away.
The latest observations bring the planet’s atmospheric temperature to about 1300C (2370F) and suggest the atmosphere contains red-tinted clouds of silicate dust. “It would be a terrible place to live,” Hinkley said. “You’d be roasted alive if you could float in the atmosphere.”
Previously, astronomers have taken direct images of some 20 exoplanets using ground-based telescopes, including HIP 65426 b. But this meant battling noise introduced by Earth’s atmosphere and limiting observations to a narrow range of visible wavelengths. By contrast, the latest images, captured from the cold, airless environment of space, cover a wide range of wavelengths, including infrared, which accounts for most of the light produced in the planet’s atmosphere.
“The best wavelength to observe a planet is the wavelength at which it produces the most intrinsic light, as it is directly related to the planet’s temperature,” said Dr. Beth Biller, co-principal investigator and astronomer at the University of Edinburgh. .
HIP 65426 b is only 10-20 million years old, much younger than Earth’s 4.5 billion year old, and the latest observations provide new insights into what Jupiter and Saturn may have looked like in their infancy.
dr. Vivien Parmentier, an associate professor of physics at the University of Oxford who was not involved in the latter work, said: “Opening a new window on the universe always brings surprises. Planets get big and shrink with time and these baby planet appears to have shrunk faster than we expected, giving us great insights into how planets form and how our own solar system came to be.”
In the future, the James Webb is expected to make detailed observations of more Earth-like distant planets, including those with potentially habitable conditions.
The findings have been published in a preprint on the Arxiv website.