I am curious (with reasons) about what will happen after an asteroid (called Valhalla 2! Valhalla 1 had collided with the Moon!) collides with Earth.

Initially, Valhalla 2 is a major fragment that split from Valhalla 1 just before the collision with the moon, with a core diameter of 70 km outrageous, Valhalla 1 collided with southern China at 62.8 kilometers per second (I know that's much faster than the fastest possible object approaching Earth in our solar system, but the halla came from outside the solar system in a hyperbolic orbit) And at an angle of 30.

Valhalla 2 crashed on land, far from any vast sea surface (surprise: I mean the ocean!), Valhalla had a density of about 3 grams per cubic centimeter, which suggests a small amount of water.

My question is: what will the climate and weather be like after the Ragnarok impact event, how long will the collision winter last (that is, if wildfires don't cause a greenhouse effect!)?

(Note: My question is in no way related to humans, I think Ragnarok occurs about a million years from the last human extinction, Just imagine that humans are out of the equation.)

  • $\begingroup$ Oh, woops, I see what I did wrong. Still pretty devastating even with the correct figures - but doesn't provide direct atmospheric changes over time, some data about ejecta to work with though I guess. $\endgroup$ Nov 14, 2021 at 11:02
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    $\begingroup$ This makes the dinosaur killer look like a toy. No idea how long the impact winter will last, though. $\endgroup$ Nov 15, 2021 at 2:18

1 Answer 1


The key here is that southern China has a lot of carbonate rocks and no major gypsum deposits, that means that the 71,000km3 direct impact zone will produce a lot of CO2 but very little in the way of sulfurous gases that absorb solar radiation in the upper atmosphere. Impact winter will likely be very short, being caused almost entirely by the dust and rock vapour thrown up, that will mix with the clouds and rain out over the course of a few years. Once surface insolation levels return to normal there will be a strong greenhouse effect that may last for centuries; this coupled with high atmospheric CO2 has the potential to boost planet growth rates worldwide. The plants will need the boost too; most of the vegetation within 5200km of the point of impact, an area of ~108 million km2, will be burned by the initial blast and many more, especially in the tropics, won't survive the cold years.


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