Where did Earth’s water come from? It’s a fundamental scientific question that has never been answered. In fact, NASA reports that we can only observe and understand 5% of the universe — with a whopping 95% remaining a complete mystery because of unobservable dark matter and dark energy. But recent research led by Michigan State University sheds new light on one phenomenon: dark comets.

Darryl Seligman, a postdoctoral fellow in the College of Natural Science’s top-ranked Department of Physics and Astronomy, is the lead author on a paper that uncovers seven new dark comets in our solar system. With this discovery, he and the research team have doubled the population of known dark comets and are the first to identify two distinct types based on differences observed in orbit and size. 

“One of the most important reasons why we study small bodies, like asteroids and comets, is because they tell us about how material is transported around the solar system,” said Seligman. “Dark comets are a new class of near-Earth objects that may contain water, so they’re a new potential source for delivering materials to Earth which were necessary for the development of life. The more we can learn about them, the better we can understand their role in our planet’s origin.”

Seligman’s research, published in the latest issue of the Proceedings of the National Academy of Sciences, not only uncovers seven new dark comets, but also compares the total known population to identify two distinct types.