Puzzling planetoids: Scientists discover 7 new mysterious "dark comets"
By zoeysky // 2025-01-04
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  • Scientists have identified seven new "dark comets," celestial objects that blur the line between asteroids and comets, bringing the total known to 14. These objects, which resemble asteroids but move like comets, could provide insights into the origins of water on Earth and the development of life.
  • Dark comets lack the visible tails of traditional comets but exhibit non-gravitational acceleration, meaning their trajectories are influenced by forces other than gravity.
  • The newly discovered dark comets fall into two distinct groups: outer dark comets and inner dark comets.
  • Dark comets may contain water ice, even in the inner solar system, challenging the traditional "snow line" theory. Their potential reservoirs of ice suggest they could have played a role in delivering water to Earth, offering clues about the origins of life.
  • The search for dark comets is set to expand with advanced tools like the Vera C. Rubin Observatory, which is expected to uncover more of these objects starting in 2025.
According to a fascinating report published in the journal Proceedings of the National Academy of Sciences, scientists have discovered seven new dark comets. The groundbreaking discovery has astronomers buzzing with excitement because experts have identified seven new "dark comets," which are celestial objects that blur the line between asteroids and comets. This latest discovery brings the total number of known dark comets to 14, a significant milestone that has allowed researchers to begin unraveling their secrets. These enigmatic objects, which look like asteroids but move like comets, could hold vital clues about the origins of water on Earth and the development of life itself. The findings also revealed that dark comets fall into two distinct families: one residing in the outer solar system and another in the inner solar system. This discovery not only deepens the mystery of these objects but also opens up new avenues for understanding their role in the formation of our solar system and the delivery of essential materials to Earth.

What are dark comets?

Dark comets are a relatively new category of celestial objects that challenge the traditional understanding of comets and asteroids. Unlike typical comets, which are often described as "dirty snowballs" made of ice, dust and rock, dark comets lack the iconic tails that form when sunlight vaporizes their icy surfaces. Instead, they appear as faint points of light, much like asteroids. However, dark comets exhibit non-gravitational acceleration, meaning their trajectories are influenced by forces other than gravity. For regular comets, this extra push comes from the sublimation of ice into gas, which creates thrust and propels them forward. But dark comets show no visible signs of outgassing, leaving scientists puzzled about the source of their acceleration. The first hints of dark comets emerged in 2016 when researchers noticed that an object called 2003 RM was deviating slightly from its expected orbit. This anomaly couldn’t be explained by the usual forces acting on asteroids, such as the Yarkovsky effect, which describes how sunlight can subtly alter an asteroid’s path. Then, in 2017, the interstellar object Oumuamua added to the intrigue. Like 2003 RM, Oumuamua exhibited non-gravitational acceleration without any visible signs of outgassing, sparking widespread curiosity about these mysterious objects.

Two families of dark comets

The discovery of seven new dark comets has allowed scientists to categorize them into two distinct groups based on their location, size and orbital characteristics. Outer dark comets Outer dark comets reside in the outer solar system, beyond the orbit of Jupiter. They are larger, with diameters ranging from hundreds of meters to several kilometers, and follow highly elliptical orbits similar to those of traditional comets. Their orbital properties suggest that they may be related to Jupiter-family comets, which originate in the outer reaches of the solar system and settle into orbits influenced by Jupiter’s gravity. Inner dark comets Inner dark comets are found in the inner solar system and are much smaller, measuring just tens of meters across or less. They follow nearly circular orbits, similar to those of the planets, and are thought to have originated in the inner region of the asteroid belt. Despite their small size, these objects also exhibit non-gravitational acceleration, hinting at the presence of ice beneath their surfaces.

The mystery of ice's existence in the inner solar system

One of the most intriguing aspects of dark comets is the possibility that they contain water ice. When the solar system formed 4.5 billion years ago, an invisible boundary called the "snow line" separated regions where water could exist as ice from those where it remained in vapor or liquid form. The snow line is located just beyond the current orbit of Jupiter, meaning objects in the inner solar system were thought to be too warm to retain ice. Yet the inner dark comets’ non-gravitational acceleration suggests they must contain some form of volatile material, likely ice, to generate the thrust needed for their peculiar motion. This raises fascinating questions about how these objects acquired their ice and whether they played a role in delivering water to Earth. The discovery of dark comets has profound implications for the current understanding of Earth’s history. Scientists have long debated how water, a key ingredient for life, arrived on the planet. One leading theory is that icy comets and asteroids delivered water during the early stages of the solar system’s formation. Dark comets, with their potential reservoirs of ice, could be a new piece of this puzzle. Daryl Seligman, a physicist at Michigan State University and lead author of the new study, suggests that dark comets may have been a significant source of the materials necessary for life’s development. "The more we can learn about them, the better we can understand their role in our planet’s origin," he said.

The search for more dark comets

Finding dark comets is no easy task. Unlike their bright counterparts, they don’t produce dazzling tails that make them easy to spot. Instead, astronomers rely on the faint light they reflect from the sun, using powerful telescopes to detect their presence. The recent discovery of the seven new dark comets was made possible by the Dark Energy Camera (DECam) in Chile, which captures detailed images of the night sky. The search for dark comets is set to accelerate in the coming years. In 2025, the Vera C. Rubin Observatory, equipped with the largest digital camera ever built, will begin scanning the skies. This state-of-the-art facility is expected to uncover even more dark comets, potentially doubling or tripling the number of known objects in this category. (Related: NASA is hiding crucial details about asteroids that could THREATEN Earth, warns senior SETI Institute astronomer.) The discovery of dark comets is a reminder of how much humans still have to learn about the solar system. These mysterious objects challenge the existing classifications of comets and asteroids and offer tantalizing clues about the origins of water and life on Earth. As scientists continue to study dark comets, they may uncover answers to some of the most fundamental questions about the planet’s history. Whether these objects are remnants of the early solar system or interstellar visitors like Oumuamua, their secrets could reshape the understanding of the cosmos and humanity's place within it. For now, dark comets remain a cosmic enigma — one that promises to inspire curiosity and discovery for years to come. Visit Space.news for more stories about interesting discoveries in outer space. Watch the video below to learn about the difference between comets and asteroids. This video is from the Finding Genius Podcast channel on Brighteon.com.

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