Recent research suggests that the hazards presented to Earth by enigmatic objects known as "dark comets" may be higher than previously believed.
These almost undetectable, fast-rotating asteroids are probably from the far side of the solar system and are roving close to Earth. They are a significant risk, but they may also supply water and other volatile materials.
Comets are typically distinguished from asteroids by their origin in the farthest regions of the solar system, where extremely low temperatures cause molecules such as water to freeze. Their orbits are occasionally disturbed by massive planets' gravitational pull, which pushes them towards the inner solar system. Comets break apart due to the heat of the sun, revealing their distinctive tails.
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Asteroids, typically found between Mars and Jupiter, are rockier and can survive longer in the sun's glare. However, they too can fall into unstable orbits, coming close to Earth.
A newly identified type of space rock, dark comets, behaves like both asteroids and comets. According to a paper accepted by the journal *Icarus*, astronomers have investigated their origins. Dark comets, only tens of kilometers across, show no visible outgassing, but they exhibit "nongravitational" acceleration, suggesting other forces are altering their orbits.
The researchers propose that dark comets are outgassing at an undetectable level, causing their acceleration. Their rapid spin indicates they are internally strong and likely originated from larger fragmented objects. Dark comets probably come from the main asteroid belt between Mars and Jupiter, disturbed by Saturn's gravitational interactions.
Their unpredictable orbits and properties make dark comets especially dangerous. To protect Earth, further detailed studies are needed to detect and predict their movements.
