Comets and asteroids were once easily distinguishable, but scientists have identified a new category of objects called “dark comets” that occupy the gray zone between the two. Dark comets are not made of ice like traditional comets, nor do they produce visible tails or outgassing, but their orbits reveal comet-like acceleration.
Researchers at Michigan State University discovered 14 dark comets, doubling the previous number of known objects in this category. The new findings indicate that these dark comets have two distinct types, with one type consisting of large, Jupiter-family comets and another type featuring smaller, more circular orbits.
The outer dark comets are thought to originate from the outer Solar System, but it’s unclear whether they were redirected by a close encounter with Jupiter. These objects may hold the key to understanding the delivery of water and other precursors of life to Earth.
Dr. Darryl Seligman, lead researcher on the study, stated that dark comets could be a new source of materials for life on Earth, including our planet’s water. The discovery of these mysterious objects has sparked excitement among scientists, who hope to uncover more about their role in the origin of our planet.
In contrast to active asteroids, which produce dust clouds around them, dark comets do not exhibit this behavior. However, their orbits suggest a comet-like acceleration, making them an important category for further study.
Source: https://www.iflscience.com/a-new-type-of-dark-comet-may-have-shaped-the-early-earth-77149