Saturn’s Moon Titan Glowing Daily at Dusk and Dawn, Find NASA-led ALMA Antennas

High in the atmosphere of Titan, large patches of two trace gases glow near the north pole, on the dusk side of the moon, and near the south pole, on the dawn side. Brighter colors indicate stronger signals from the two gases, HNC (left) and HC3N (right); red hues indicate less pronounced signals. Image Credit: NRAO/AUI/NSF

New mapping of Saturn’s moon Titan made by high-precision antennas located in Chile has revealed large patches of trace gases glowing near the north and south poles, making it look brighter at dusk and dawn.

These regions are curiously shifted off the poles, to the east or west, so that dawn is breaking over the southern region while dusk is falling over the northern one, said the study led by NASA.

“This is an unexpected and potentially groundbreaking discovery,” said Martin Cordiner, an astrochemist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the lead author. “These kinds of east-to-west variations have never been seen before in Titan’s atmospheric gases. Explaining their origin presents us with a fascinating new problem.”

ALMA antennas observed the gas-rich areas in Titan’s atmosphere glowed brightly and the ALMA’s sensitivity helped the researchers to obtain spatial maps of chemicals in Titan’s atmosphere from a “snapshot” observation that lasted just three minutes.

Titan’s atmosphere is like a chemical factory that uses energy from the sun and Saturn’s magnetic field to produce a wide range of organic, or carbon-based, molecules.

So far, Titan has been visited by two spacecraft and one surface lander. Voyager 2 made the first flyby of Titan in 1980. The Cassini spacecraft has made scores of flybys of Titan since 2004. The Huygens probe, carried to Saturn by Cassini, parachuted to the surface in 2005.

The current study by ALMA antennas located in Chile helps understand Earth’s origin and very early atmosphere, which may have been similar as it is on Titan now, which is the most earth-like in the solar system with lakes, seas and flowing rivers, although the liquid is methane (CH4) and ethane (C2H6) instead of water. Moreover, like Earth, Titan’s atmosphere is mostly nitrogen (N2) and its atmosphere is slightly denser than Earth’s.

Interestingly, these findings substantiate observations made by NASA’s Cassini spacecraft earlier about a cloud cap and gases over the pole that is experiencing winter on Titan.

One day on Titan takes about 16 Earth days. The length of Titan’s day is the same as the amount of time it takes Titan to orbit Saturn. Saturn makes a complete orbit around the sun (one Saturn year) in about 29 Earth years (10,759 Earth days). Since it is locked by gravity to Saturn, the same side always faces Saturn.

Some scientists believe that life is not feasible on Titan but many others think that Titan’s subsurface might contain a habitable environment. Seas on Titan are named for mythical sea monsters, while its mountains are named for mountains found in the works of author J.R.R. Tolkien.

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