NASA’s years-long dream comes true as Webb telescope peers into Saturn’s moon Titan

Scientists have waited for years to study the atmosphere of Titan and their dream has now come true thanks to the James Webb Space Telescope. Titan is Saturn’s largest Moon and is also the only planetary body other than Earth that has rivers, lakes, and seas. These lakes and rivers, however, do not have water but what flows in them instead are hydrocarbons including methane and ethane. 

In addition to this, Titan has an atmosphere filled with a thick haze that obscures visible light reflecting off the surface, and that is where Webb comes in. NASA has now used Webb’s infrared capabilities to study Titan’s atmosphere, including its weather patterns and gaseous composition, and also see through the haze to study bright and dark patches on its surface. Titan holds immense significance among astronomers because they believe its atmosphere can tell a lot about the Moon’s past and even future. 

Peering into Titan

Using the Webb telescope’s Near-Infrared Camera (NIRCam), the scientists discovered a large cloud in Titan’s northern hemisphere and soon confirmed the presence of a second one. Astronomers say clouds validate long-held predictions from computer models about Titan’s climate, that they would form readily in the mid-northern hemisphere during its late summertime when the sun heats the surface.

[Evolution of clouds on Titan over 30 hours between Nov. 4 and Nov. 6, 2022, as seen by Webb NIRCam (left) and Keck NIRC-2 (right); Image: NASA]

The team of astronomers is being led by Conor Nixon from NASA’s Goddard Space Flight Centre who wrote to his team members, "There appears to be a large cloud, we believe over the northern polar region near Kraken Mare", in a mail. After spotting clouds in Titan's atmosphere, the astronomers then used the Keck Observatory in Hawai'i to compare the evolution of the clouds in two days.

In the images above (which are blurry due to Titan's dense atmosphere), NASA explained, "Cloud A appears to be rotating into view while Cloud B appears to be either dissipating or moving behind Titan’s limb (around toward the hemisphere facing away from us)". Currently, the team is carrying out follow-up studies using Webb's Near-Infrared Spectrograph (NIRSpec) that is collecting spectra to gain access to wavelengths that do not reach ground-based telescopes.

Once they get Titan's data from NIRCam and NIRSpec and Mid-Infrared Instrument (MIRI), another instrument of Webb, in May or June of 2023, scientists will be able to learn more about the composition of Titan’s lower atmosphere and surface and the bright feature seen over the south pole.