NASA has revealed the discovery of seven additional “dark comets,” doubling the known total to 14. These enigmatic objects, which blur the line between asteroids and comets, challenge long-held assumptions about near-Earth objects (NEOs) and may hold clues to the origins of Earth’s water and life.
NASA discovers seven new dark comets
A new study published in the Proceedings of the National Academy of Sciences identifies two distinct groups of dark comets based on their size, reflectivity (albedo), and orbital paths. Outer dark comets reside in the outer solar system and are larger, often hundreds of meters across, with highly elliptical orbits resembling Jupiter-family comets. Inner dark comets, on the other hand, are found in the inner solar system near planets like Earth, Venus, and Mars. These are smaller, often tens of meters wide, and travel in nearly circular orbits. This distinction suggests a diverse origin and evolutionary path for these objects within our solar system.
What are dark comets?
Dark comets are a recently defined category of NEOs. While they resemble asteroids in appearance—devoid of the bright coma characteristic of traditional comets—they exhibit behaviors more akin to comets, such as sudden accelerations. This behavior suggests they might be emitting jets of gas, although no visible evidence of such activity, like a tail, has been detected. These objects are also unusually dark, much like the interstellar visitor 1I/‘Oumuamua, which passed through the solar system in 2017.
Mystery behind dark comets and their unique traits
The first dark comet, identified in 2016, was asteroid 2003 RM. Its trajectory revealed unexplained deviations, typically associated with comets emitting gas. However, the object displayed no visible tail or outgassing, earning it the nickname “The Asteroid that Wanted to be a Comet.” The mystery deepened in 2017 with the discovery of ‘Oumuamua. This interstellar visitor exhibited comet-like acceleration despite resembling an asteroid in appearance. Together, these discoveries led scientists to consider a new category of celestial bodies: dark comets.
Dark comets and the origins of life on Earth
Dark comets may play a critical role in Earth’s history. Some researchers theorize that these objects could have delivered water and organic materials essential for life during the planet’s early formation. A 2023 study suggested that between 0.5% and 60% of all NEOs might be dark comets originating from the asteroid belt between Mars and Jupiter. Their icy composition aligns with theories that comets, rather than asteroids, were the primary carriers of water to the inner solar system.
Challenges of studying dark comets
Tracking and analyzing dark comets is no easy feat. Their low albedo makes them difficult to detect using traditional telescopes, and their unusual accelerations challenge existing models of orbital mechanics. “Dark comets are a new potential source for having delivered the materials to Earth that were necessary for the development of life,” said Darryl Seligman, lead author of the recent study. “The more we can learn about them, the better we can understand their role in our planet’s origin.”
Dark comets and their role in unraveling planetary mysteries
Dark comets remain one of the most intriguing mysteries in planetary science. With each new discovery, researchers uncover more about their behavior, origins, and potential impact on Earth’s history. However, these findings also raise new questions about their formation, structure, and role in the solar system’s evolution. The ongoing study of dark comets is not just about understanding these celestial bodies—it’s about unlocking the secrets of our own planet’s beginnings and securing a clearer view of the dynamic, ever-changing universe we inhabit.
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