I have binge watched a lot of documentaries and movies about meteors hitting the earth. The one pattern I have seen, even in the science-fact documentaries like Nova, is that the animations show meteors hitting the earth on the day side. By that, I mean at a near 90° angle in the center of the day zone. As if it were to hit the earth at high noon.

What seems unlikely to me is where the meteor hits. It seems intuitive to me that statistics would favor a meteor strike on the night side of the planet rather than the day side. Or, possibly from the transition between day and night if the meteor came in from the side.

Is my suspicion correct? Is it unlikely for a meteor to hit the earth on the day side and far more likely to hit the night side?

To clarify, I'm thinking of significant meteor strike, like the Chicxulub impact that killed off the dinosaurs. If something that massive came in from the day side, wouldn't it more likely to have been captured or redirected by the sun because of the sun's gravity?


Remember that the Earth, and the meteoroid, are both in orbit around the sun. As the meteoroid approaches Earth, it will also curve due to Earth's gravity. If you imagine the Earth to be stationary and the meteoroid to be moving in a straight line your intuition is likely to be wrong.

The result of the complex dynamics is that there is no time or direction from which it is impossible for a meteoroid to have come from. On average the direction of impact is 45 degrees, and the timing is somewhat more likely in the morning when the rotation of Earth combines with its movement through space. A direct impact at noon, from the apparent direction of the sun, is unlikely but possible.

When you look at lists of meteors, many are at night. Except the brightest fireballs, a meteor is much more noticeable at night.

Nasa hs a database of boloids: http://neo.jpl.nasa.gov/fireballs/ By combining the UT time with the latitude information it is possible to get an estimate of the local solar time of the fireball: Local solar time of boloids since 2007

This histogram of time of impact of about 250 fireballs since 2007 shows no particular decrease around midday. The documentary graphics may show an apparently fully lit earth, and a perpendicular impact as it is easier to recognise the Day side of the Earth, and it looks more dramatic.

  • $\begingroup$ Does that database discuss the relative likelihood of meteor strikes from the leading hemisphere (side of the Earth facing the direction of revolution around the sun) vs. trailing hemisphere? Sort of like the infamous "running thru raindrops" scenario. $\endgroup$ – Carl Witthoft Mar 20 '17 at 15:05
  • $\begingroup$ @CarlWitthoft I'd hoped to see something of that effect. However, that's not something that I see in the data. I haven't done the analysis, but it looks consistent with a uniform distribution to me. $\endgroup$ – James K Mar 20 '17 at 21:26
  • $\begingroup$ @Carl Witthoft: The plot shows local solar time, so 6 is approx. sunrise and should be the facing side. You would have to compare 0-12 with 12-24. $\endgroup$ – Grimaldi Mar 24 '17 at 21:39
  • $\begingroup$ @Carl Witthoft: From the graph I would estimate there are about 10 more in the first half than in the second half of the day. That's 10 more heads than tails out of 250. So is our coin biased in this dataset where p= 130/250 = 0.52? Not very conclusive, I would say with-out knowing, how much of an effect the movement should have (most things in the ecliptic plane move roughly in the same direction). $\endgroup$ – Grimaldi Mar 24 '17 at 22:00

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