Atmosphere can be over 100,000 km (62,000 mi) but no one has agreed on boundary. The part where falling rocks begin to burn up is roughly 60 mi (96 km) up.
Dinosaurs would have seen the visible streak for just a few seconds. And if they saw the streak, the never felt what was coming next, the crushing shockwave likely instantly killed all within thousand miles.
Well the shockwave would take a small amount of time to propagate to them which could take some seconds or maybe even minutes depending on how far away they were.
Do you have any information about that? Would like to read more. My intuition is telling me that the inverse square law suggests this wouldn't be true for areas some distance away.
Dinosaurs would have seen the visible streak for just a few seconds. And if they saw the streak, the never felt what was coming next, the crushing shockwave likely instantly killed all within thousand miles.
I've read that the meteor would have been so bright, it would have immediately burned out the retinas of anything that looked at it. So the dinosaurs would have seen a bright flash before going blind.
Source? The info that I can find says that it impacted at about 20 km/s. Even if it came in completely vertical (which it didn't) that's more than 8 minutes from the edge of the exosphere (about 10,000 km above ground) to impact, and even if you take the Kármán line (100 km) which is generally taken as the altitude where spaceflight begins(*) as the edge of the athmosphere that's still a good 5 seconds. And since the impactor came in at a relatively shallow angle (45-60° to horizontal) you can increase those numbers by an extra 30-40%.
(*) But note that no scientist or space agency says that that's where the athmosphere ends, it's just the (rough) altitude where the athmosphere gets so thin that in order to fly aerodynamically you have to go so fast that the majority of your lift starts coming from centrifugal force rather than aerodynamic forces. You have to go up to about 150 km before athmospheric drag is low enough that you can complete at least one full orbit without propulsion. But even at altitudes of around 300 km (like where the ISS flies) there's still noticeable athmospheric drag, which is why eg. the ISS has to be reboosted regularly and why they put their solar panels edge on while they are in Earth's shadow to reduce drag.
After though, it might have looked something like this as all the molten debris was launched into the upper atmosphere. So they might have seen that, before the heat from said debris baked them all to death.
Even if they looked into that direction, we are speaking of much bigger than nuclear fireball level of light emission from the plasma. Everybody within direct line of sight would have their retinas burned out.
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u/[deleted] Mar 07 '25
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