But the JWST images show that we won’t have to wait until 2034 to get new beautiful and scientifically important images of Titan. The moon was observed on 4 November 2022 by the near-infrared camera NIRCam (programme GTO 1251, PI Conor Nixon). Titan is enveloped by a thick N2–CH4 atmosphere that blocks most of the visible and infrared light, so for most wavelengths we just see that, like on the left image obtained at 2.12 μm. Such observations are still interesting because they can detect atmospheric phenomena such as hazes and clouds, both visible in the image. However, some narrow windows in the infrared allow us to probe down to the surface. The middle image is a composite of three wavelengths near some of these windows (blue = 1.40 μm; green = 1.50 μm; red = 1.99 μm — not true colours, then) and both atmosphere and surface can be observed. Using this colour combination Titan appears almost Mars-like and various known albedo surface features, marked in the image, can be identified. The clouds appear to be in the northern hemisphere, as expected by models for this season (late summer). One of them (cloud A) appears to be hovering near the largest among Titan’s northern polar methane lakes, Kraken Mare, hinting at a connection.
In order to follow the evolution of the clouds, the authors reached out to another big telescope — an Earth-based one this time — to ask for unplanned follow-up observations: Mauna Kea’s Keck Observatory. In an act of sheer altruism, at least one other team donated some of its precious Keck time on 6 and 7 November and the result is shown in the right image (note that the colours are different, as Keck’s are all around the 2 μm window: red = 2.06 μm; green = 2.12 μm; blue = 2.13 μm). Not only does Titan look as beautiful as ever, but the clouds are still there around the same locations, with a slightly different shape. They might be the same as (or similar to) the 4 November ones, but surely they are indicative of high cloud activity in this season. As clouds are rarer on Titan than on Earth, this discovery is a serendipitous one.
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