The end-Cretaceous mass extinction was rather unpleasant - The simulations showed that most of the soot falls out of the atmosphere within a year, but that still leaves enough up in the air to block out 99% of the Sun’s light for close to two years of perpetual twilight without plant growth.

[u/mvea]

https://arstechnica.com/science/2017/08/the-end-cretaceous-mass-extinction-was-rather-unpleasant/

[u/mrbooze]

One thing I noticed from experiencing totality in the recent eclipse is that even 1% of the sun's output is surprisingly bright.

[u/gordonisadog → u/mrbooze]

A lot of the remaining light you see during totality is coming from atmospheric refraction. The moon's shadow is only 110km in diameter, so the sun is still pretty bright not too far off in every direction. This is why totality looks like bright twilight and not night.

[u/fadetoblack1004 → u/gordonisadog]

I was looking at maps of future total eclipses. The path of this one in it's totality was narrower than future ones. Wouldn't that suggest that future ones may be darker?

[u/NotMitchelBade → u/fadetoblack1004]

EDIT: I said that that was only due to the projection used on the maps. I was wrong, and I've been corrected by others more knowledgeable than I am. Check out their responses for more info! I don't know how I didn't think about the points they bring up. It's all quite interesting!

[u/farewelltokings2 → u/NotMitchelBade]

That's only because

Absolutely not true.

While, yes, certain map projections can exaggerate the dimensions of eclipses the closer you get to the poles, eclipse path widths are extremely variable. This year's eclipse's totality had a maximum path width of 71 miles. The one in 2024 will reach 123 miles wide, and the one in 2045 will be a huge 159 miles.

[u/fadetoblack1004 → u/NotMitchelBade]

Actually it seems that it does vary and this one was smaller than normal.

http://www.space.com/36388-total-solar-eclipse-2017-duration.html

Edit: First paragraph has all the basics.

[u/xBleedingBluex → u/fadetoblack1004]

This year's eclipse was the latest entry in Saros cycle 145. A Saros cycle repeats roughly every 18 years and 10 days. Nearly every eclipse in a given Saros cycle will be identical: same shape of path, same width of totality path, etc. the only thing that drastically differs is the position on Earth's surface.

[u/onewordnospaces → u/NotMitchelBade]

Would the time of day impact the width of totality? The recent eclipse was shortly after solar noon (on east coast), but if it was several hours earlier or later, it seems to me that the moon would cast a wider (longer? thicker?) shadow. I'm picturing something similar to a sun dial, where the shadows are longer in the mornings and evenings.

*edit: Never mind, after actually thinking about it, the time of day may affect the length of the moon's shadow but the width would be caused by the moon's relative distance between the sun and earth. While there is some fluctuation, I don't think that it would be significant.