Fallout from an ancient asteroid collision still rains on Earth

astronomy.com ^ | Tuesday, January 24, 2017 | Nathaniel Scharping

[BenLurkin]

At the moment, we seem to experiencing a fairly heavy rain of rocky meteorites called ordinary chondrites, which are distinguished by the presence of drop-like structures embedded in their bodies. Chondrites are further divided into three classes: H, L and LL, each thought to correspond to a different impact event long ago. We’re currently seeing a disproportionate number of H and L-type chondrites hit the Earth, but, it wasn’t always so.

Looking at a slice of time around a million years before the event, the researchers took a census of the meteorites that intersected the Earth’s orbit, and found that the cosmic rain looked very different back then.

Instead of the L- and H-chondrites that we see today, a different kind of meteorite, called achondrites, made up nearly half of the micrometeorite impacts in the Ordovician. Anywhere from 10 to 29 percent of these were a type of achondrite that likely resulted from a massive collision on Vesta, the second-largest asteroid in the solar system at over 300 miles in diameter.

Achondrites are meteorites that appear to have been melted and reformed at some point in their lives, such as on Vesta, where molten lava flows likely reshaped the surface at some point early in its life. Today, achondrites are considered rare, say the researchers.

In addition, there were many more LL-chondrites and fewer H-chondrites during the Ordovician. While the origins of these meteorites remain unclear, they likely result from periodic collisions among asteroids and other objects in the solar system, as well as gravitational perturbations from planets that alter the path of the millions of asteroids and other objects floating around the solar system.

[Paladin2]

Hunh. Chicken Little WAS right....

[soycd]

In an orbital world, what came around goes around.

[Ciaphas Cain]

Whether you hold to a strict creationist conviction or the scientific theory about accretion, it is nonetheless remarkable that our Earth continues to accumulate mass. Including some amount of water per day from bits of ice that get captured by gravity and become part of the atmosphere.

Of course there is climate change. The cosmos sees to that. No human intervention required.

[NutCrackerBoy]

Interesting article to contemplate, but ...

[We’re] doing space exploration with geological methods, essentially. -Philipp Heck, the curator of meteorites for the Field Museum and lead author of the paper.

That seems an exaggeration. We get to learn something about collisions in the solar system that have occurred at different times. What then? The materials from the collisions are made up of just ho-hum stuff. We classify what type of asteroid got bumped at this time or that time.

[CardCarryingMember.VastRightWC]

Exxon’s fault. Greenhouse gases are poking holes in the atmosphere that allow these asteroids to enter and kill people. Women, children & LGBTQ are the most vulnerable.

[PIF]

Then again were he still alive Tom Van Flandern would have disagreed ... see also Exploded Planet Hypothesis 2000.