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A circular molecule spotted on Saturn’s moon Titan may help form precursors to life. This compound hasn’t been seen in the atmosphere of any planet or moon before.

The molecule is called cyclopropenylidene and is made up of three carbon atoms in a ring with two hydrogen atoms attached. Conor Nixon at NASA’s Goddard Space Flight Center in Maryland and his colleagues spotted it floating in Titan’s thick atmosphere using the Atacama Large Millimeter/submillimeter Array in Chile.

Finding this molecule on Titan was a surprise. It is extremely reactive – if it bumps into any other particles, it tends to be quick to chemically react with them to form new compounds. Because of this, it had previously only ever been seen in tenuous clouds of gas and dust in interstellar space. Somehow, it lasts in the upper layers of Titan’s skies.

Ring-shaped molecules like this tend to act as the building blocks of molecules necessary for life, such as DNA and RNA. “This is a really small building block, but you can build bigger and bigger things with it,” says Nixon. “I don’t think anyone necessarily believes that there’s microbes on Titan, but the fact that we can form complex molecules like this on Titan could help tell us things like how life got started on Earth.”

Conditions on Titan now may be similar to those on Earth early in the planet’s history, when the air was dominated by methane instead of oxygen. Studying its potential for life could help us learn about the beginnings of life here as well.

Titan has the biggest variety of molecules on any moon or planet we have investigated, says Nixon. ”It’s sort of this happy hunting ground for new things,” he says. “Molecules like this are almost an early warning sign that there’s more exciting chemistry to be found.”

Right now, we can only look for that from Earth, but the Dragonfly spacecraft, planned to launch in 2027, will examine Titan’s surface up close.

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