Quote :

"Astronomy Show | Hide November 6, 2007 Rise Set Actual Time 7:00 AM EST 5:36 PM EST Civil Twilight 6:34 AM EST 6:02 PM EST Nautical Twilight 6:04 AM EST 6:32 PM EST Astronomical Twilight 5:34 AM EST 7:02 PM EST Moon 3:59 AM EST 3:46 PM EST Length Of Visible Light: 11h 28m Length of Day 10h 35m Tomorrow will be 1m 49s shorter."

What does Civil, Nautical, and Astronomical Twilight mean?

Which tells me when the sun is actually rising, when will I be able to see... Also I'm going to be down in the Nantahala Gorge... so any guess how much that will affect dawn?

11/6/2007 1:08:29 PM

http://en.wikipedia.org/wiki/Twilight#Definitions

11/6/2007 1:09:53 PM

Basically during civil twilight even though the sun has "set" it is still light out enough to do day time tasks like read a book (although the dimness would probably give you eye strain), throw a football, find something you dropped on the ground etc w/o artificial lighting.

Nautical Twilight is when it is too dark out to be able to perform tasks outside or to see much w/o artificial lighting. However, a glow exists in the distance from where the sun is rising/ just set. You can start seeing the stars at this point thus the origins of the name nautical from when the sailors of the old days could start using the stars for navigation purposes.

Astronomical Twilight Is non-distinguishable for 99% of civilians and only effects astronomers attempting to look up at the stars at this point their is still minor interference from refracted sunlight preventing full resolution.

Mathematical Definition

Civil- Sun < 6 degrees below horizon
Nautical- Sun is > 6 degrees but < than 12 degrees below horizon
Astronomical- Sun is >12 degrees but < than 18 degrees below the horizon

11/6/2007 2:28:49 PM

thxu

[no homo]

11/6/2007 3:06:21 PM