Saturn's Titan's Building Blocks May be Older Than the Sun

It turns out that Saturn's moon, Titan, may have building blocks that are older than the sun itself. Scientists have found evidence that nitrogen in the moon's atmosphere originated in conditions similar to the cold birthplace of the most ancient comets from the Oort cloud, revealing a bit more about the origins of both Saturn and Titan.

Nitrogen is the main ingredient in the atmospheres of both Earth and Titan, and Titan itself shares many similarities with Earth. Unlike our own planet, though, the moon is locked in a deep freeze.

In order to learn a bit more about Titan, the researchers examined its atmosphere. They found that the ratio of one isotope of nitrogen, nigrogen-14, to another isotope, nitrogen-15, was such that it was impossible for it to change significantly as it evolved over time. In fact, Titan's atmosphere contains so much nitrogen, that no process can significantly modify this tracer even given more than four billion years of solar system history. The small amount of change in this isotope allowed the scientists to compare Titan's original building blocks to other solar system objects.

Previously, scientists believed that it was possible that Titan's building blocks formed within the warm disk material that surrounded infant planet Saturn during its formation. Yet this latest evidence shows that this isn't the case. Instead, Titan's building blocks formed early in the solar system's history within the cold disk of gas and dusk that formed the sun.

The findings don't just have implications for Titan, though; it also has implications for Earth. It supports the view that ammonia ice from comets is actually not likely to be the primary source of Earth's nitrogen.

"Some have suggested that meteorites brought nitrogen to Earth, or that nitrogen was captured directly from the disk of gas that formed the sun," said Kathleen Mandt, one of the researchers, in a news release. "This is an interesting puzzle for future investigations."

The findings are published in the Astrophysical Journal Letters.