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Circling in a plane at sunset, you can see the sun (and bask in its light) for much longer than if you were on the ground below. It’s the same for the atmosphere. Light rays from below the horizon strike the upper atmosphere. The light is refracted (bent) as it passes through air molecules, as well as scattered every which way. The softly illuminated sky creates the twilight, an hour or so of afterglow before night sets in.
In fact, there are actually four categories of twilight. During the evening, it all starts with sunset itself, ending when the Sun has just dipped below the horizon. That’s “sunset twilight.”
Next comes “civil twilight.” During civil twilight it is still light enough to carry on most outdoor activities, like playing tag on the lawn or watering a garden. Big shapes are still visible during this early twilight, even without street lamps or porch lights lit. You may see a few bright stars or planets in the sky. In the continental U.S., civil twilight lasts for about 30 to 60 minutes, depending on the time of the year (evening twilight is longest in the summer) and the location. It ends when the sun is about 6 degrees below the horizon.
Then there’s “nautical twilight.” During nautical twilight, the sky is dark enough that all the brighter stars are visible. However, someone at sea could still sea the horizon well enough to navigate by star altitudes. By the end of nautical twilight, the Sun has sunk to 12 degrees below the horizon, and the horizon is no longer visible at sea.
Finally, there’s “astronomical twilight.” More and more stars can be seen, but the sky is still too light for an astronomer to do any serious work. When the sun has dipped to 18 degrees below the horizon, twilight
Originally posted by jeichelberg
reply to post by DisIllusioned PatRiot
I can appreciate dusk and some glow; however, dusk round these parts does not usually linger a half-hour...and I thought Sunset meant Sunset...
(Q) Why is it in current events? (A) Because it happened today...