It was a cloudy day on Titan.
That was evident on the morning of Nov. 5 when Sébastien Rodriguez, an astronomer at the Université Paris Cité, downloaded the first images of Saturn’s largest moon, taken by NASA’s James Webb Space Telescope. He spotted what appeared to be a large cloud near Kraken Mare, a 300-meter-deep sea in Titan’s north polar region.
Sign up for the New York Times’ The Morning newsletter
“What a wake up call this morning,” he said in an email to his team. “I think we see a cloud!”
It caused something of a weather emergency among the Al Rokers of the cosmos, leading them to run for more cover.
Titan has long been a jewel of astronomers’ curiosity. Less than half the size of the Earth, it has its own atmosphere thick with methane and nitrogen – and even denser than the air we breathe. When it rains on Titan, it rains gasoline; when it snows, the pollens are black as coffee grounds. The lakes and streams are full of liquid methane and ethane. Under the frozen, silty crust lurks an ocean of water and ammonia.
Future astrobiologists have long wondered if the chemistry that prevailed during Earth’s early years is being recreated in Titan’s muddy mounds. The potential progenitors of life make the smoggy world (where the surface temperature is minus 290 degrees Fahrenheit) a long-awaited hope for the discovery of alien chemistry.
To that end, missions are being planned to Titan, including sending a nuclear-powered drone called Dragonfly to orbit Saturn’s moon by 2034, as well as more imaginary journeys like sending a submarine to explore its oceans.
However, despite observations by Voyager 1 in 1980 and the Cassini Saturn orbiter and its Huygens lander in 2004-5, planetary scientists’ models of Titan’s atmospheric dynamics were still only tentative in the meantime. But the Webb telescope, which launched nearly a year ago, has infrared eyes that can see through Titan’s haze.
So when Conor Nixon of the NASA Goddard Space Flight Center got the email from Rodriquez, he was thrilled.
“We had waited years to use Webb’s infrared vision to study Titan’s atmosphere,” Nixon said. “Titan’s atmosphere is incredibly interesting, not only because of its methane clouds and storms, but also because of what it can tell us about Titan’s past and future, including whether it has always had an atmosphere.”
That same day, Nixon contacted two astronomers — Imke de Pater of the University of California, Berkeley, and Katherine de Kleer of the California Institute of Technology — who were affiliated with the dual 10-meter Keck telescopes on Mauna Kea in Hawaii and have called themselves the Keck Titan team. He requested immediate follow-up observations to see if the clouds were changing and what direction the wind was blowing from.
As de Pater explained, such last-minute requests are not always possible, as telescope time is a precious commodity.
“We’ve been extremely lucky,” she said.
The observer on duty that night, Carl Schmidt of Boston University, was working with them on other planetary studies.
The Keck staff, de Pater added, is also eager to support Webb telescope observations.
“They like the solar system objects,” she said, “because they’re just neat and always changing over time.”
With Keck’s visible-light images and infrared images from the Webb telescope, Nixon and his colleagues were able to examine Titan from features on the ground through the different layers of its atmosphere — everything a long-range weather forecaster might need.
And more is on the way.
In an email, Nixon said his team was particularly excited to see what would happen in 2025, when Titan would reach its northern autumn equinox.
“We saw a giant storm on Titan shortly after the last equinox, so we’re excited to see if the same thing happens again,” he said.
© 2022 The New York Times Company