“Dark comets” are much more common than previously thought and may have delivered water to Earth … [+]
Where did water come from on Earth? About 71% of the Earth’s surface is oceans, which contain 97% of the Earth’s water. Human bodies are 55-60% water. Its origin is a missing link in scientists’ understanding of the history of our planet and life on it.
A new article published earlier this month in Icarus argues that a new category of space rocks called “dark comets” are much more common than previously thought and may have delivered water to Earth long ago. A newly defined type of near-Earth object — comets and asteroids whose sun orbits bring them close to Earth — dark comets are asteroids that accelerate suddenly, suggesting they may be releasing jets of gas, as comets do. They are a new class of objects somewhere between an asteroid and a comet.
Frozen bodies
The study, which examined seven dark comets, estimates that between 0.5 and 60% of all near-Earth objects may be dark comets from the asteroid belt. These dark comets appear to contain ice – something that asteroids do not – although there is evidence that ice exists on some asteroids in the main asteroid belt between Jupiter and Mars. “We think these objects came from the main belt of inner and/or outer asteroids, and the implication is that this is another mechanism for introducing some ice into the inner solar system,” said Aster Taylor, author main work and one. graduate student in astronomy at the University of Michigan. “There may be more ice in the main inner belt than we thought. There could be more objects like this out there.”
“Dark comets” are somewhere between an asteroid and a comet.
The asteroid belt
Whether Earth’s water came from dark comets is still being determined because the timelines make it difficult to find evidence. “Near-Earth objects don’t stay in their current orbits very long because the near-Earth environment is chaotic,” Taylor said. “They stay in the near-Earth environment for only about 10 million years.” The solar system is about 4.5 billion years old.
Research shows that the main belt of asteroids is the most likely source of near-Earth objects.
“We don’t know if these dark comets delivered water to Earth. We cannot say that. But we can say that there is still debate about how exactly the Earth’s water got here,” Taylor said. “The work we’ve done has shown that this is another route to get ice from somewhere in the rest of the solar system to Earth’s environment.”
The solar system has a major asteroid belt roughly between the orbits of Mars and Jupiter.
The Age of Water
Research in 2023 suggested that all water on Earth is older than the Sun. Scientists found at least 1,200 times the amount of water in all of Earth’s oceans around a very young star in the early stages of its evolution about 1,305 light-years from the solar system in the constellation Orion. This supports a theory that water comes from the interstellar medium, the gaseous and dusty regions of space between stars. It shows that the water in our solar system formed billions of years before the sun.
Separate research showed that the water on Earth did not come from meteorites – the debris from a comet, asteroid or meteoroid that hits the Earth’s surface – which were found to be among the driest extraterrestrial materials ever measured.
Another paper describing the discovery of salt crystals in samples of the asteroid Itokawa – brought to Earth in 2010 by Japan’s Hayabusa mission – supports the theory that all water on Earth’s surface originally came from asteroid impacts.
Take my books Stargazing in 2024, A stargazing program for beginnersAND When is the next eclipse?
I wish you clear skies and open eyes.