Is it possible to determine what daytime the Chicxulub impactor striked the Earth 66 mya? Was it day or night, what was the current phase of the Moon etc.? Can sediments, rhytmites or something else hold this information?

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    $\begingroup$ @JamesKilfiger - The questioner isn't asking on about the specific time on a specific date that the Chicxulub impactor hit the Earth. He or she is asking if there's any way to know the time of day (without knowing the date), or time of month (without knowing the season or year). There's a big difference. The answer is "most likely no" as opposed to "there's no way tell". $\endgroup$ – David Hammen Mar 7 '16 at 22:39
  • $\begingroup$ if you ask what "time of day" (what TZ??) did an asteroid strike the earth, is that basically like asking if it hit from the "outside" of Earth orbit (so, in to a dark bit of Earth at that moment) or the "inside" (so, in to a light bit of Earth at that moment). In fact, are both of those things even possible? Can an asteroid strike from either the "out" or "in" side of Earth orbit?? $\endgroup$ – Fattie Jul 5 '16 at 12:37
  • $\begingroup$ @JoeBlow Yes, notice how the asteroids pictured here have orbits intersecting Earth's, and thus can approach Earth from inside its orbit. $\endgroup$ – called2voyage Aug 5 '16 at 13:06
  • $\begingroup$ It's unkown and there is no current data for that. It most probably landed on the leading edge of the earth as it orbits the sun, something like 80 percent of shooting stars are concentrated on the early morning side of the planet, a bit like Chelyabinsk meteor from 2013 that hit russia in the early morning. It's quite likely that the Asteroid that killed the dino's hit between 1AM and 1PM, and also quite likely that it hit from 4 to 10AM. I don't know how that fares for big meteorites, it's data from the major shooting star monitoring project that has 10,000+ statistics. $\endgroup$ – com.prehensible Jul 21 '18 at 17:44
  • $\begingroup$ The scientific value of knowing which time of day the impact arrived would be a lot less than other studies of the impact. It's totally random, although the earth does tend to escape bolides one one time of day and collect them on the other. $\endgroup$ – com.prehensible Sep 24 '18 at 7:00

Given that the uncertainty in deltaT, the difference between the uniform dynamical time needed to predict the positions of the Sun and the Moon and civil (solar) time was already 4.5 hours by year -4000 (https://eclipse.gsfc.nasa.gov/SEcat5/uncertainty.html), then I would say by 65 million years ago we would have no idea of which way the Earth was facing at the time. Unless the dinosaurs left eclipse records that would let us calibrate the much faster spinning Earth back then, we would have no means to work out what time of day the impact happened.


There are various graphs that illustrate this kind of angle of incidence for average meteors. enter image description here

That's the best scientific indicator that we have regarding daytime: it was significantly more likely to occur either side of dawn.

Specific scientific evidence would have to come in the form of biochemical markers from fossils, which is possible but practically impossible. One of the few fossils from the KT boundary was found 13cm below it, a Ceratopsian dinosaur horn, about a year previous, and we'd need multiple fossils from the same day.

Difficult to recover data from a 10 billion Hiroshima explosions that happened 65,500,000 years ago.


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