The first James Webb images of Titan, Saturn's largest moon, were captured early on an extraordinary Saturday morning on November 5, to the great joy of a global team of planetary scientists. NASA researchers had been eager to use this telescope to examine Titan's atmosphere in order to learn more about its weather patterns and other aspects.
Titan is the only known planetary body other than Earth that has rivers, lakes, and seas. It is also the only moon in the solar system with a thick atmosphere, and because of the its heavy haze, visible light reflecting off the surface is obscured.
However, unlike Earth, the liquid on Titan's surface is constituted of hydrocarbons such as methane and ethane rather than water.
The picture depicts a Webb image of Titan, which stands up against space's void like a huge red marble. Titan's lower atmosphere and clouds are seen in the image captured by Webb's NIRCam instrument, using a 2.12-micron filter.
Titan can be seen in many degrees of red, ranging from almost black to almost white. There are three highlighted areas. Spot along the edge at 11 o’clock is labelled ‘Cloud A.’ A larger, brighter spot at 1 o’clock is labelled ‘Cloud B.’ A nearly white, crescent-shaped spot along the bottom from about 5 to 7 o’clock, is labelled ‘Atmospheric Haze.’
Three surface features are also labelled — a bluish green patch near Cloud A as ‘Kraken Mare (methane sea),’ a dark brown area below the centre as ‘Belet (dark-colored sand dunes),’ and a small pale spot just inside the edge around 4 o’clock as ‘Adiri (bright patch).’
The two clouds that Webb observed in the photograph confirmed theories that have been around for a while that clouds occur in Titan's northern hemisphere in the late summer when the Sun heats its surface. Clouds were also seen in follow-up observations by the Keck Observatory, confirming seasonal weather patterns.
"Titan’s atmosphere is incredibly interesting, not only due to its methane clouds and storms, but also because of what it can tell us about Titan’s past and future – including whether it always had an atmosphere. We were absolutely delighted with the initial results," said Principal Investigator Conor Nixon who worked on the Guaranteed Time Observation (GTO) program 1251 team that uses Webb to investigate Titan’s atmosphere and climate.
The team of scientists quickly established that a bright light seen in Titan's northern hemisphere was, in reality, a sizeable cloud, by comparing several photographs taken by Webb's Near-Infrared Camera (NIRCam). Not long after, they noticed a second cloud.
"Detecting clouds is exciting because it validates long-held predictions from computer models about Titan’s climate, that clouds would form readily in the mid-northern hemisphere during its late summertime when the surface is warmed by the Sun," they informed.
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