If we look into the area in which the Earth orbits the Sun, we will find many rocks. Over 35,000 Near Earth Objects: Asteroids and comets sometimes Get in our corner It leaves the solar system before plummeting again.
There are likely many more out there, and a new study suggests that up to 60 percent of them could be intriguing objects known as “dark comets” — mysterious rocky bodies that once contained or still contain ice.
According to a team of astronomers led by Astor Taylor of the University of Michigan, this could provide important clues about where Earth got its water from when the solar system was still in its infancy.
“We don’t know if these dark comets delivered water to Earth. We can’t say that. But we can say that there is still debate about how Earth’s water got here.” Taylor explains.
“Our study shows that this is another pathway that could deliver ice to the Earth environment from elsewhere in the solar system.”
Rocks moving freely in the solar system can take many different forms. The most well-known are asteroids and comets. Asteroids are dry rocks, while comets are icy rocks that move closer to the Sun and start to release material when they heat up. (Meteors are rocks that enter a planet’s atmosphere, while meteorites are chunks that fall onto a planet’s surface.)
However, there are many variations within these two space rock categories. There is some overlap between them.Dark comets are thought to be a type of hybrid, but not much is known about them.
A vague “coma‘Or the gaseous atmosphere and the tail produced by sublimation of ice are not the only two features diagnostic of a comet. Another is its acceleration.
When a comet ejects material, that ejection gives the comet more momentum than would be expected if the rock was simply rock. asteroid The comet is only subjected to gravity, and this outgassing may cause the comet to rotate faster.
A dark comet is one that doesn’t have a visible coma or tail, but does have this additional non-gravitational acceleration when measured. Taylor and his colleagues studied seven known dark comets to get a better understanding of how many more dark comets lurk in near-Earth space.
The team estimates that between 0.5 and 60 percent of all near-Earth objects could be dark comets.
This is a pretty big gap and needs to be narrowed down, but the results so far suggest that there may be more frozen material in our solar system, not just around Earth, but also in the asteroid belt that orbits the sun. Mars and Jupiter.
“These objects are thought to come from the inner and/or outer main asteroid belt, suggesting that this is another mechanism for introducing ice into the inner solar system.” Taylor says.
“There may be more ice in the inner main belt than we thought. There may be other objects like this. This could be a significant portion of the closest population. We don’t really know, but these discoveries are raising many more questions.”
They explain that near-Earth objects don’t tend to linger around our home planet for very long, cosmically speaking: Gravity is so intense in the inner solar system that near-Earth objects only last around 10 million years.
The solar system was formed about 4.6 billion years ago, and since near-Earth objects are not depleted, the supply must be constantly replenished.
The team performed simulations to assign non-gravitational accelerations to different classes of objects in the solar system to see where dark comets originate from. They then ran them to see where they ended up. This suggests that most of the dark comets near Earth originate from the main asteroid belt.
But remember accelerated rotation? Comets can spin so fast that they disintegrate. By the centrifugal force of rotationComet fragments are also made up of ice and gas, and they rotate and move under non-gravitational acceleration, meaning you get a ton of rock for the price of one.
Of the seven dark comets analyzed by the research team, 2003RMappears to be a larger rock ejected from the main belt, while the other six are the product of centrifugal fragmentation of a larger rock that broke apart as it left the main belt and approached the Sun.
“Follow-up observations of dark comets from ground and space will allow us to measure their outgassing rates and compositions, potentially constraining their dynamical origins.” The researchers write in their paper:.
“Future survey missions may identify many more dark comets than are currently known, thereby improving our understanding of this evolutionary path and the populations from which it originated.”
This study Icarus.
