There are three stages of twilight: civil, nautical, and astronomical.

Civil twilight is the period between sunset and the time at which the center of the Sun's disk is 6 degrees below the horizon. I assume it is called "civil twilight" because at the end of civil twilight it is difficult or impossible to work outside without artificial lights. You'll probably notice street lights near your home coming on at the end of civil twilight rather than right after sunset. Depending on your latitude civil twilight ends a little less than half an hour after your local sunset. (The Sun moves 15 degrees per hour along the ecliptic, but if you live at higher northern or southern latitudes the ecliptic is highly inclined.)

Nautical twilight is the period between sunset and the time at which the Sun is 12 degrees below the horizon. At 12 degrees, it becomes difficult to find the horizon, which means you can no longer use a sextant to take your bearings (important when you're trying to navigate at sea). This is a little more than 45 minutes after sunset.

Astronomical twilight as Webster says runs from sunset until the Sun is 18 degrees below the local horizon. After this point, there will be essentially no scattered sunlight contributing to airglow, meaning you'll have a truly "dark" sky (or as dark as it will get at least). At research observatories, observations usually begin in earnest after astronomical twilight, since scattered sunlight just contributes to noise in your observations. (Aside: astronomers often image the nearly uniform twilight sky to make "flat fields," to test the CCD imaging camera response as a function of position on the chip.) Astronomical twilight ends about an hour and fifteen minutes after sunset.

Same thing goes for morning twilight, just replace "sunset" with "sunrise" and run things backwards.

The most inspiring member of X-Nation 2099, part of the 2099 series published by Marvel Comics. She and the rest of her team of young mutants (Caravan, Clarion, December, Metalsmith, Nostromo, Uproar, Willow, and Wulff) gathered in Halo City, Nevada.

She projects a "sphere of influence" a few feet around her body in which the laws of reality are at her command. Considering her powers, she was understandably self-centered, until she developed deeper feelings for Metalsmith, who was almost immediately attracted to her and quickly joined X-Nation.

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(The argument has been made that Twilight's powers are analogous to how decisions are made by anarchists. Those decisions that most affect a person should be made by that person. When a decision affects many people, the amount of influence each person has over the decision should be based on how much the decision would affect that person... and the rest of society, the community, is there to help make sure such decision-making guidelines are followed.)

Like many teenage girls, I had a less than healthy obsession with vampires. There's something sensual about vampire novels--I'm sure you know what I'm talking about. My fascination began with books like Anne Rice's Interview with a Vampire and Bram Stoker's Dracula. While I read the novels and had lots of typical daydreams of some day being "bitten," I never went so far as to role play or anything more. Eventually I moved on to other things and I thought I was over that phase in my life.

That is, until Friday, when a student let me borrow her copy of Twilight, by Stephenie Meyer. I knew this book was a new favorite among my female students, which ordinarily means I'd hate the book. But, heaven help me, I judged a book by its cover. The sleek, black jacket portrays two pale arms holding the reddest of apples. If I'd turned it over and read the synopsis, a cliché wrapped in platitudes, I probably would've handed it back to her without a second thought. I didn't, though, and I couldn't be happier about that.

The story seems standard enough: new girl in a small town school notices a group of classmates that all seem different, beautiful, and sophisticated. Bella soon discovers they are vampires and falls dangerously in love with Edward, the group's leader. Yes, this book is mostly young romance, with hints of action and mystery. The author makes a strong effort to target a young teen audience, I'd say 13-16. She stays away from all the usual inappropriate topics: drugs, alcohol, sex. Bella eats balanced meals and does all her homework; no one in the book so much as curses. For all that, this book is actually very sexy.

Bella and Edward's relationship is enigmatic at first. It appears he hates her, but as the book goes on we soon find out why. The way Meyer describes the attraction and chemistry between them made my breath catch more than once. She did a masterful job of building the suspense of Bella and Edward's relationship, the climax of which is one of the most erotic kisses I've ever read about. The fact that she achieves this goal without ever lifting a shirt or mentioning genitalia is no small feat.

I would highly recommend this book to anyone looking for a quick and easy read. It's a terrific book for teens; although the writing itself is standard, it'll keep their attention without introducing undesirable behaviors or content that's too mature. Moreover, it's the first in The Twilight Saga, a series Meyer continues to write. Series books typically keep their fans reading, a huge plus when considering the average teen reader. I haven't picked up the second book yet, but I'm dying to know what happens. Yeah, this phase is definitely not over.

Twi"light` (?), n. [OE. twilight, AS. twi- (see Twice) + leoht light; hence the sense of doubtful or half light; cf. LG. twelecht, G. zwielicht. See Light.]

1.

The light perceived before the rising, and after the setting, of the sun, or when the sun is less than 18° below the horizon, occasioned by the illumination of the earth's atmosphere by the direct rays of the sun and their reflection on the earth.

2.

faint light; a dubious or uncertain medium through which anything is viewed.

As when the sun . . . from behind the moon, In dim eclipse. disastrous twilight sheds. Milton.

The twilight of probability. Locke.

 

© Webster 1913.

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Twi"light`, a.

1.

Seen or done by twilight.

Milton.

2.

Imperfectly illuminated; shaded; obscure.

O'er the twilight groves and dusky caves. Pope.

 

© Webster 1913.