It’s been one of the great mysteries of the last half century: how a meteoroid crashed through the surface of the moon.
But one of our most famous discoveries, the meteorite that created the crater of the diamond moon, may never be found.
The asteroid impactor, dubbed Chicxulub, broke apart and spewed out a series of fragments, some as small as one-tenth the size of a pea, into space.
It was just one of a huge number of asteroids that hit the moon in the last century and a half, killing millions of dinosaurs, and sending rocks and fragments into space that have stayed with us.
What exactly happened?
How does the asteroid impact change our understanding of the early days of the planet?
In short, the asteroid impacted the moon at a very low altitude, a few hundred kilometres above the surface.
“You’ve got to remember that the moon is a huge ocean, so the asteroid did not break up into a million pieces,” says John Grisham, a paleontologist at the University of Queensland in Brisbane.
“Its just a bit of rock and ice, so you don’t see a lot of debris.”
Instead, the moon was hit by the impact at high speed, and the fragments came flying out at the speed of light.
“That’s how fast it moved,” says Grishamp.
“It’s just a tiny speck that got pushed into space.”
There was a lot going on, says Grisamp.
The meteoroid was travelling very fast, and there was debris going in all directions.
The impact site was so close to the surface that the meteoroid would have broken apart, he says.
“If you were flying at that speed, you’d have a pretty good chance of hitting the Moon, and you would probably kill the dinosaurs, too.”
There were several different possibilities for the impact site, says Michael J. Brown, a professor of astronomy at the Massachusetts Institute of Technology in Cambridge, Massachusetts.
Some fragments could have been scattered all over the surface, and some fragments could even have hit the surface at a higher velocity.
Some of the fragments would have hit at a depth of around 5km.
“A lot of the debris would have gotten sucked into the crater,” Brown says.
This could have caused a huge crater, where a meteor could have landed.
It could also have caused the meteor to be torn apart into smaller fragments, leaving a crater that was not visible.
It’s not known exactly how large the crater was, but there are some theories.
It would have been so large that the impactors impact was the only way for the fragments to hit the Earth.
Some people think that if there was a big crater, it would have torn the moon apart, and it would then have blown away the moon into space, as a result of its gravity, according to Brown.
“And that’s how it would end,” he says, because of the gravity, “because the meteor would have ripped the moon back up.”
Some experts think that the crater could have contained a lake of water, which could have allowed the meteoroids to hit it.
The crater’s size and the way it was shaped are among the best indications of how far the meteor hit, says Brown.
The other possibility is that the fragment was going to hit near the moon’s surface, where it could have broken up and landed on the surface below, as it would break up under the moonlight.
This would have resulted in the meteor crashing into the surface and sending fragments into the deep ocean below, where they could then impact the Earth, Brown says, although he points out that this scenario is not necessarily a good one.
Brown thinks that if the meteor struck the Moon at a velocity of about 200km per second, and was flying at an altitude of about 100 kilometres, the impactor would have reached the Moon within five minutes.
“There is no question in my mind that the comet that fell through the atmosphere of the Earth in 1815 would have had to have had a velocity between 200 and 300km per hour to have been able to impact the Moon,” he explains.
The fragments may have been small, but they would have crushed up the moon before they hit the ground.
The size of the crater is one of those things that you don.t necessarily want to speculate about, says Scott C. Smith, a geophysicist at the US Geological Survey in Salt Lake City.
“The size of this crater is something that you want to focus on, because if you were looking at the size and shape of the impact crater, you would have a lot more confidence that this would have happened,” he adds.
But the impact might have been as large as it is now, and if so, it could be even more massive than previously thought.
“In the past, when people had the idea that the size was small, you could get away with saying that the Moon is a little bit larger than we thought,” says