First look inside Uranus for 30 years discovers it has 13 rings and is stuffed with fuel

NASA chiefs took advantage of an unusual cosmic event to get their first detailed glimpse inside the mysterious planet this century and were able to measure some key features of Uranas’ atmosphere

Boffins have had a rare peek inside Uranus – and found it has 13 rings and is full of gas.

Excited NASA chiefs took advantage of an unusual cosmic event to get their first detailed glimpse inside the planet, named after Greek god of the sky Ouranos, this century.

It recently moved perfectly between Earth and a distant star to create a stellar occultation. This flickering of starlight created something called a light curve, a powerful tool for unlocking secrets hidden high in the planet’s skies.

By watching how the star’s light dimmed and brightened as it passed behind Uranus, scientists could measure key features of the planet’s atmosphere including its temperature, pressure and density.

It is two billion miles from Earth and has an atmosphere composed primarily of hydrogen and helium. Uranus does not have a solid surface but a soft one made of water, ammonia and methane.

It is known as an ice giant because its interior contains an abundance of swirling fluids with low freezing points. While Saturn is the most well-known planet for having rings, Uranus has 13 of its own composed of ice and dust.

But it is not easy to locate. In 1986 NASA’s Voyager 2 became the first and only spacecraft to fly past the planet – 10 years before the last stellar occultation occurred in 1996.

Uranus’ exact position is only accurate to within 100 miles which makes analysing the new atmospheric data crucial to future exploration.

William Saunders, planetary scientist at NASA’s Langley Research Center in Hampton, Virginia, US, said: “Uranus passed in front of a star that is about 400 light years from Earth.

“As Uranus began to occult the star, the planet’s atmosphere refracted the starlight, causing the star to appear to gradually dim before being blocked completely. The reverse happened at the end of the occultation, making what we call a light curve.

“By observing the occultation from many large telescopes, we are able to measure the light curve and determine Uranus’ atmospheric properties at many altitude layers.”

The detailed data from the planet’s stratosphere – the middle layer of its atmosphere – will help scientists understand how its climate works, how it has changed over decades and what to expect for future missions.

NASA led an international team of 30 astronomers from 18 observatories to get the rare view of Uranus. It lasted an hour and was only obtainable from western North America.

“This was the first time we have collaborated on this scale for an occultation,” said Saunders.

“I am extremely grateful to each member of the team and each observatory for taking part in this extraordinary event. NASA will use the observations of Uranus to determine how energy moves around the atmosphere and what causes the upper layers to be inexplicably hot.

“Others will use the data to measure Uranus’ rings, its atmospheric turbulence, and its precise orbit around the Sun.”

NASA spent five months planning for the moment and did a test run.

Emma Dahl, a post-doctoral scholar at Caltech in Pasadena, California, US, who observed from the US space agency’s Infrared Telescope Facility on the summit of Mauna Kea in Hawaii, said: “As scientists we do our best work when we collaborate.

“This was a team effort between NASA scientists, academic researchers, and amateur astronomers. The atmospheres of the gas and ice giant planets are exceptional atmospheric laboratories because they don’t have solid surfaces.

“This allows us to study cloud formation, storms, and wind patterns without the extra variables and effects a surface produces, which can complicate simulations very quickly.”

NASA chiefs are already planning for the next similar event in 2031 which should be even brighter.