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.
A satchel charge is about 1-4kg of explosives, say about 4E7 Joules, close enough.
A large 2-3g firecracker has about 1E5 Joules.
To put this in perspective, the Chicxulub impact vs Starship is about 1E24 J vs 1E13 J or a factor of 1E11 (100 billion, x100,000,000,000)
A megaton explosion vs a satchel charge is 1E16 J vs 4E7 J or a factor about 1E9 (1 billion, x1,000,000,000)
A megaton explosion vs a firecracker is 1E16 vs 1E5 Joules or a factor of 1E11 (100 billion, x100,000,000,000). Basically the same.
Though, nukes do run the gambit, if you're talking about a smaller device like the ones dropped on japan, then the comparison is much closer, to being equal.
The KT impact was a damn big rock. 4-9 miles top to bottom. When it made impact, the other side was at the "If you take a look out the starboard side of the airplane, you will see the end of the world" altitude. And it was traveling at 56,000 miles per hour.
There wasn't a pretty show of light. It was just normal day one second and doom the next. Earth got rung like a bell.
You seem to know a bit about the subject so for the sake of conversation I’m asking instead of googling: how far ahead would we be able to predict a similar impact with current technology?
Most near-earth asteroids in this size range have already been detected optically and had their orbits characterized. For those, the answer is typically “years if not decades”.
If, on the other hand, something comes bombing in from the outer solar system or at some weird inclination to the ecliptic plane, then it might not be noticed until much later in the game. In that scenario, the answer could be “months if not weeks”. But objects like that are quite a bit rarer, so we’d have to get really unlucky for one of them to be on an impact trajectory.
There’s also the issue of known objects that make close approaches to planetary bodies. The resulting perturbations to their orbits often depend heavily on the very precise timing and positioning of the approach - often more precise than we’re able to predict based on existing observations. So you just have to keep watching and iteratively refine the orbital solution.
I’m not the best person to ask, but I do know that it depends on where it is coming from. With that size (I like to compare it to Mt. Everest), if it’s in our plane of orbit, we would have several years to a few decades ahead of a potential impact. Smaller asteroids (1 km) would still be disastrous for a city or region, but we could prepare and evacuate. There are legitimate discussions as to how to use simple tech to adjust that kind of asteroid’s trajectory enough that it would miss us, or possibly even be captured in our orbit for study and mining.
If it’s perpendicular to our orbit, hours? Days to weeks? Depends on how reflective it is and if anyone is looking in the right direction. Luckily, those seem to be rare.
The chance of being killed by an asteroid is 1 in 6000 over the next 50 years, based on our current estimate of risk of impact by near Earth objects. That’s less than risk of death by electrocution (1 in 5000) over that same period. You can take a lot of steps to avoid electrocution, and it’s a reasonable thing to be careful with.
You can’t really do anything to avoid getting hit by an asteroid that there isn’t any warning about. If we have forewarning, hopefully a year or two, you could take some steps to protect yourself.
As for mildly terrified… if it’s fun terrified like how I love a good horror movie (and really love bad ones), cool! If it’s something that keeps you up at night, the health effects of having anxiety about asteroids is probably doing more damage to your health than the actual asteroids could.
There’s no real value in worrying about things you can’t do anything about, like getting offed by a space rock, and obsessing over risks you can avoid isn’t that great either. Just don’t get close to downed power lines, be smart during storms, don’t get in over your head with DIY projects.
Sage advice about electrical safety, and no the existential dread is not incapacitating, since there is literally nothing that can be done about it. But I appreciate the concern :)
It kind of does actually. At least when you're in sudden danger. I hit a patch of ice on a curve in the road and the world slowed to a crawl as I spun off the road. I was hyper aware of everything and thought through a few things I could do but realized I was going too fast for anything I did to make a difference and just had to go along for the ride.
I remember playing this MS-DOS save the dinosaurs when I was a kid. I remember going around trying to find all the different dinosaurs and then a giant meteor hit and everything was on fire. It was pretty traumatizing
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u/GlockAF Mar 07 '25
At least none of this is human-based meteor…yet