Is it possible to determine what daytime the Chicxulub impactor struck the Earth 66 Mya? Was it day or night, what was the current phase of the Moon, etc.? Can sediments, rhythmites or something else hold this information?
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3$\begingroup$ @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 HammenCommented Mar 7, 2016 at 22:39
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1$\begingroup$ 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?? $\endgroup$– FattieCommented Jul 5, 2016 at 12:37
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$\begingroup$ @JoeBlow Yes, notice how the asteroids pictured here have orbits intersecting Earth's, and thus can approach Earth from inside its orbit. $\endgroup$– called2voyage ♦Commented Aug 5, 2016 at 13:06
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1$\begingroup$ 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. $\endgroup$– bandybabboonCommented Jul 21, 2018 at 17:44
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1$\begingroup$ 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. $\endgroup$– bandybabboonCommented Sep 24, 2018 at 7:00
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2 Answers
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Various graphs illustrate the times and areas of the globe where meteorites are more likely to hit.
That's the best scientific indicator regarding daytime: it was significantly more likely to occur either side of dawn, just like a car travelling forwards hits moths, the dawn side of our planet is like the front side of a car collecting rocks.
Daytime markers from fossils are very rare. Currently, there are seasonal markers which demonstrate that the strike happened in springtime. They compared bones of freshwater fish from Tanis and from today and found that the growth rings of the fish correspond to springtime.ref
Difficult to recover data from a 10 billion Hiroshima explosions that happened 65,500,000 years ago.
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1$\begingroup$ Do you have a link/DOI for the source of that graph? $\endgroup$ Commented Mar 21, 2021 at 12:05
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$\begingroup$ Sorry I can't find the exact version of that image, but there are 5-6 different copies here: google.com/… $\endgroup$ Commented Mar 21, 2021 at 18:03
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$\begingroup$ Just curious to read more. Thanks. $\endgroup$ Commented Mar 21, 2021 at 18:11
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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.
answered Jul 21, 2018 at 4:38