It's always darkest before the dawn.
It's always darkest before the dawn.
Are you just making stuff up from your own head or has somebody actually told you that this is true? Either way, you're totally and completely wrong. Sunset is the time when the sun has gone down below the horizon, and the sun is bright enough that we can still see the light coming from it for a while even after it's set low enough that you can't see the actual sun. That has nothing to do with the speed of light. It takes light about 8 minutes to get from the sun down to earth, but that also means that we see the sun itself as being where it was 8 minutes ago rather than where it actually is now. Once we see the sun go down below the horizon, the speed of light doesn't affect how long it stays light in any way at all.
Alphatroll wrote:
It's however long it takes the light to reach us after the sun disappears.
Whatver the speed of light is relative to the actual distance the sun is away from Earth.
When the sun is gone, the light is still getting here for a while.
Alphatroll wrote:
It's however long it takes the light to reach us after the sun disappears.
Whatver the speed of light is relative to the actual distance the sun is away from Earth.
When the sun is gone, the light is still getting here for a while.
The speed of darkness thread got deleted but the revolutionary theory I came up with there applies here too.
In particular, the only light that has been studied is observed light, because it has to be observed to be studied. So for light to follow the laws of physics, i.e. jump from the sun to the Earth, there has to be someone observing it.
At night, everyone goes to sleep, and the Earth turns and points away from the sun, so that there is nobody observing it anymore. So the light stops jumping from the sun to the Earth and pushing the dark out of its way. This allows the dark to return to its normal state, which is everywhere, surrounding everything. It is essentially "dark matter," the stuff scientists are finding out almost the entire universe consists of.
So to answer the OP's question, the dark matter returns instantly as soon as the light stops. This would happen exactly at sunset if people on the ground were the only ones looking, but there are also birds flying around in the air that can see below the horizon, so it stays light a while longer. How long depends on how high the birds are flying.
Sailors at sea can also view the sun slightly longer because of the transparent water, which is "nautical twilight." And cosmonauts in low Earth orbit can see it even longer for "astronomical twilight."
"revolutionary theory"
That right there is LetsRun.com gold.
Here on google maps for dusk time.
Well I feel you ask a damn good question that needs an answer at the particular time it is needed. Good question!
original hmmmm? wrote:
I recognize my writing style and creating this thread 4+ years ago. It's always interesting seeing one of my threads from years back occasionally be bumped back up to the top.
It takes 8 minutes for the light to reach earth traveling 186,000 miles per second
varies based on lattitude and longitude and what not
The time you can no longer see is called civil twilight. A good rule of thumb though is 15 mins on trails, 30 on the road. 15 on road when its cloudy and 5-10 on trails when its cloudy.
What I find impressive is the geometrical distribution of bright- and darkness around the equinoxes, it's almost quadratic: I visualized it with some rather crude formula at
(right now we are at the 4:40 mark and getting back to "sine-wavey").
PyEphem is a really good Python package for these calculations and will use proper formulas.
That may be the funniest thing I have ever read! Well done.
That may be the funniest thing I have ever read! Well done.
Did you mean so say where the Moon is in its rotation around the Earth? As far as I know, the Sun doesn't rotate around anything. :-)
Ummmmm the sun doesn't rotate around the Earth. Earth *revolves* around the sun and I would hope you know that if your are in a grade higher than 4th and 5th grade because I learned this in 4th grade
ffff wrote:
It depends where the Sun is in it's rotation around the Earth.
30 minutes where I live. It's not that hard to figure out.. Just time it one night yourself.
www.timeanddate.comshould tell you for your city
Thanks! That's a terrific website. It shows ALL the twilight times, Civil, Nautical, & Astronomical and the time it becomes Night. Astronomical twilight is always more than an hour (to an hour and a half) after Sunset, so it's a lot more than 30 minutes from Sunset to dark. Two hours until full Night.
I ought to incorporate that the distant chance that you are running in a tree lined crevasse when the sun sets, it will appear to get dull a lot quicker. I get what proportion of time it needs to get weak and not perceiving how expedient it can get weak in express conditions is something that can freeze you.