NASA discovers seven mysterious 'dark comets' that might have brought life to Earth

This artist’s concept shows interstellar object 1I/2017 U1 (‘Oumuamua) after its discovery in 2017. While itself not a dark comet, ‘Oumuamua’s motion through the solar system has helped researchers better understand the nature of the 14 dark comets discovered so far. (Image: NASA)

Astronomers have uncovered seven new “dark comets,” doubling the total known. These enigmatic celestial bodies blur the line between asteroids and comets. The findings, published on Monday in the Proceedings of the National Academy of Sciences, reveal intriguing differences among these objects.

Tracing the Origins of Dark Comets
The first dark comet was identified less than two years ago. Shortly after, astronomers located six more, sparking curiosity about their behaviour. Unlike typical comets, dark comets lack visible tails but exhibit comet-like movements due to outgassing.

In 2016, asteroid 2003 RM baffled scientists when its orbit shifted unexpectedly. This deviation could not be explained by common asteroid forces, prompting further study. “We suspected outgassing might be causing the thrust,” said NASA’s Davide Farnocchia. “Yet it appeared just like an asteroid.”

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The mystery deepened in 2017 with the discovery of ‘Oumuamua, the first known interstellar object. It displayed similar traits, behaving like a comet while looking like an asteroid. These findings reinforced the idea that dark comets were more common than previously thought.

Two Types of Dark Comets Identified
With 14 dark comets now known, researchers have categorised them into two groups. Outer dark comets are large, with highly elliptical orbits, resembling Jupiter-family comets. Inner dark comets, however, are smaller and have nearly circular orbits within the inner solar system.

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“Analysing their albedo and orbits revealed distinct differences,” said Darryl Seligman, lead author of the study and a postdoctoral fellow at Michigan State University. These findings could hold clues to their formation and unique behaviours.

Exploring Their Role in Earth's Origins
The study raises fascinating questions about dark comets’ origins and potential significance. Could these objects have carried vital materials for life to Earth? Researchers hope future studies will shed light on their role in the solar system's evolution.

“Dark comets may hold secrets about life’s beginnings,” said Seligman. “The more we study them, the clearer their role becomes.”