twilight

Yesterday, I looked up the time for sunrise for Monday morning. In the process, I remembered that there are a lot of cool things to know about sunset, sunrise, and twilight. So if you got excited about reading about the pop culture series, that’s not what I’m writing about. Rough, I know, but keep reading to learn about original twilight.

Did you know that actually, scientifically speaking, “twilight” can refer to the period of time right before sunrise as well as the time right after sunset? According to several things I’ve read, there is what is called morning twilight and evening twilight.

There are also technically three different types of sunrises and three types of sunsets. Civil twilight, nautical twilight, and astronomical twilight. So if you’re talking to some smart jerk and ask him when sunrise/sunset is, you can now be prepared to specify when he asks. One of my favorite authors, Vincent Bugliosi, mentioned the types of sunrises in one of his books, And the Sea Will Tell. When I get a chance, I’ll dig up how he explained it (’cause he did it well) and add that to this post also. But here’s what I’ve got so far.
According to Wikipedia, coupled with knowledge from two other sites it is:

–  Night, if the sun is more than 18 degrees below the horizon

–  Astronomical twilight, the sun is between 12 and 18 degrees below the horizon

Nautical twilight, when the sun is between 6 and 12 degrees below the horizon

Civil twilight, the sun is 6 or less degrees below the horizon

Day, when the sun is above the horizon

So from what I can surmise, the story of light in a single day goes like this. It’s night. The comes astronomical twilight, when the sun is between 12 and 18 degrees below the horizon. It’s still pretty dark. When the sun is between 12 and 6 degrees below the horizon, objects are becoming distinguishable, it’s nautical twilight. At 6 degrees below the horizon, it’s civil twilight, and it’s light enough to do things outside without the aid of artificial lights.

Sunrise is defined as the moment where the sun becomes visible on the horizon. It appears that dawn refers to the whole transition from dark to sunrise. And twilight, since it can be sued for both morning and night, is the period of time where it’s light out, even if it’s before the sun has risen or after the sun has set.

So then reverse the process, I guess, to count down to sunset. It’s called evening twilight. The sun disappears from sight, which is sunset. Then you go back through the steps, civil, nautical, astronomical twilights, and then night.

Sources:
http://en.wikipedia.org/wiki/Dawn
http://en.wikipedia.org/wiki/Twilight
http://aa.usno.navy.mil/faq/docs/RST_defs.php
http://www.timeanddate.com/worldclock/aboutastronomy.html

Advertisements

4 Comments

Filed under Breaking news, Everyday

4 responses to “twilight

  1. Anna

    Very interesting! And with your new water color set, you should paint the three twilights 🙂 I think it would be a neat series!

  2. tcm.

    Will this get published? Or must I be a member for this sort of thing to occur? Hmm…I shouldn’t mind, I think, to be a member. This looks like an interesting site to learn from…

    But yes. I agree with Miss Anna, that you should definitely paint them. (Exact, of course, with the true degree difference).

    Can you post pictures?
    <

  3. baggervais

    See, isn’t science worth knowing?

  4. Pingback: Top Posts « Philosophizings from the Flat

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s