ALMA sniffs out atmosphere of Saturn’s moon Titan 

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The planet Saturn is known for its beautiful rings. But Saturn also has dozens of moons. The largest one is called Titan. It’s a bit larger than the planet Mercury and a bit smaller than Mars. And it’s the only moon in the solar system with a thick atmosphere. 

Astronomers already knew that the atmosphere of Titan contains lots of nitrogen gas, just like the atmosphere of our own planet Earth. In addition, Titan’s atmosphere contains so-called hydrocarbons, like methane and ethane. 

Because Saturn is very far from the sun, Titan is extremely cold: 180 degrees Celsius below zero. As a result, methane and ethane gas can exist as liquids on the surface, in the form of hydrocarbon lakes. In fact, Titan is the only celestial body in the solar system – apart from Earth – where you could swim or take a boat ride (except that you would instantly freeze to death)! 

Now, astronomers have detected a peculiar molecule in Titan’s atmosphere. It’s called vinyl cyanide. Its chemical formula is C2H3CN. The interesting thing is that molecules of vinyl 

cyanide may hook up to each other in the form of tiny spheres – a bit like the outer walls of living cells. This process could take place in the hydrocarbon lakes on Titan’s surface. 

The discovery was made by ALMA. Back in early 2014, ALMA carried out observations of Titan. When astronomers took another look at the data, they found the signature of vinyl cyanide: ALMA had detected the millimeter radiation emitted by these molecules. 

It’s important to realize that ALMA has not detected living cells on Titan. It’s not even clear whether or not the vinyl cyanide molecules on Titan have really hooked up into tiny spheres. Nevertheless, some chemical reactions on this large moon of Saturn may resemble the chemical reactions on Earth that led to the formation of life, almost 4 billion years ago. 

What? 

Titan is the largest moon of the planet Saturn, and the second-largest moon in the solar system. Its diameter is 5,150 kilometers. Titan was discovered in 1655 by Dutch astronomer Christiaan Huygens. In the 1950’s, another Dutch astronomer, Gerard Kuiper, discovered that Titan has an atmosphere. Space probes like Voyager 1, Voyager 2 and Cassini have studied Titan in much detail. Still, ground-based observatories like ALMA can still make important discoveries about the chemistry going on in the atmosphere of this unique moon. 

Who? 

ALMA observations of Titan were carried out between February and May 2014. The data were stored in the ALMA archive. They have now been studied in detail by a team of astronomers led by Maureen Palmer of NASA’s Goddard Space Flight Center in Greenbelt, Maryland (USA). Maureen and her colleagues published their discovery in the magazine Science Advances. They hope to use ALMA in the future to find other complex molecules in Titan’s atmosphere.

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