# Dawn and dusk across America

FMF
Science 23 May '09 08:05
1. FMF
Main Poster
23 May '09 08:05
Are the east coast and west coast of the USA both in darkness at the same time for a certain period of time every day?

How long does this 'overlap' last?

How much does it vary according to latitude and time of year?

Approximately what is the maximum number of Americans that might normally be expected to be asleep (because it's "night" for them) at any one time?
2. 23 May '09 10:071 edit
Originally posted by FMF
Are the east coast and west coast of the USA both in darkness at the same time for a certain period of time every day?

How long does this 'overlap' last?

How much does it vary according to latitude and time of year?

Approximately what is the maximum number of Americans that might normally be expected to be asleep (because it's "night" for them) at any one time?
…Are the east coast and west coast of the USA both in darkness at the same time for a certain period of time every day?
..…

Yes, it is called night time.
Is that question a misprint? -I just find it hard to imagine that this is what you really meant to ask.
3. AThousandYoung
West Coast Rioter
23 May '09 10:20
Originally posted by FMF
Are the east coast and west coast of the USA both in darkness at the same time for a certain period of time every day?

How long does this 'overlap' last?

How much does it vary according to latitude and time of year?

Approximately what is the maximum number of Americans that might normally be expected to be asleep (because it's "night" for them) at any one time?
When it's 9pm in New York it's 5pm in Los Angeles. Assuming about eight hours of darkness per night, it would seem that for four hours the entire country is experiencing night (or at least the continental US). This might be from 9pm to 1am PST, or 1am to 5am EST.
4. FMF
Main Poster
23 May '09 11:07
Originally posted by Andrew Hamilton
[b]…Are the east coast and west coast of the USA both in darkness at the same time for a certain period of time every day?
..…

Yes, it is called night time.
Is that question a misprint? -I just find it hard to imagine that this is what you really meant to ask.[/b]
I thought it was a 6 hour time difference.
5. FMF
Main Poster
23 May '09 11:09
Originally posted by AThousandYoung
When it's 9pm in New York it's 5pm in Los Angeles. Assuming about eight hours of darkness per night, it would seem that for four hours the entire country is experiencing night (or at least the continental US). This might be from 9pm to 1am PST, or 1am to 5am EST.
How are these timings affected by latitude?
6. 23 May '09 12:22
Originally posted by AThousandYoung
When it's 9pm in New York it's 5pm in Los Angeles. Assuming about eight hours of darkness per night, it would seem that for four hours the entire country is experiencing night (or at least the continental US). This might be from 9pm to 1am PST, or 1am to 5am EST.
The difference is only 3 hours. Or do NY and LA have different summer time standards?
7. 23 May '09 12:23
Originally posted by FMF
How are these timings affected by latitude?
8. 23 May '09 13:30
Originally posted by FMF
How are these timings affected by latitude?
Latitude affects the length of the night. At this time of the year, it doesn't get dark at all in the northernmost parts of the US.
9. FMF
Main Poster
23 May '09 14:12
Originally posted by Nordlys
Latitude affects the length of the night. At this time of the year, it doesn't get dark at all in the northernmost parts of the US.
Yes. That's why I asked 'How are these timings affected by latitude?'

Do you mean Alaska? Or do you mean Oregon and Maine?

How long is day/night in Florida and dooes it change much with the seasons?
10. 23 May '09 20:45
This web site kind of shows what you are talking about.

http://spaceflight.nasa.gov/realdata/tracking/index.html

Also, you can get times and dates when the space station is going over your town. We got to see it here last night, it is pretty amazing and brighter than I thought it would be.
11. 24 May '09 07:46
Originally posted by FMF
Are the east coast and west coast of the USA both in darkness at the same time for a certain period of time every day?

How long does this 'overlap' last?

How much does it vary according to latitude and time of year?

Approximately what is the maximum number of Americans that might normally be expected to be asleep (because it's "night" for them) at any one time?
I suggest you use a model globe depicting the earth and its continents, and aim a light source to it. This will be the Earth and the Sun. Then put the globe into a light rotation, and you'll see what happens with the shadow.

I live at a latitude of 57 degrees north. Here we can easily see how the summer nights and winter days will be short. In our ancient religion we worship the midsummer day, and the midwinter day. The spring solstice means a lot for us. Up north in Sweden at mid summer, the sun is up the whold night, and at the mid winter it's not possible to see it at all, there is no daylight then.

All this can be shown by your globe and an artificial sun.
12. 24 May '09 17:08
There are 4 time zones from coast to coast: Eastern, Central, Mountain and Pacific. But you do have to take into consideration Daylight Savings Time as some states use it and others do not. Assuming that the states in question all use Daylight Savings Time, then amount of over lap will be the number of hours of darkness minus 3.
13. 28 May '09 17:49
Originally posted by Eladar
There are 4 time zones from coast to coast: Eastern, Central, Mountain and Pacific. But you do have to take into consideration Daylight Savings Time as some states use it and others do not. Assuming that the states in question all use Daylight Savings Time, then amount of over lap will be the number of hours of darkness minus 3.
Actually, use of Daylight Savings Time will have no effect on the amount of darkness overlap between places. It only affects what their clocks say when it happens.
14. 29 May '09 14:57
That's true. I was thinking about simply subtracting the actual time differences. If there should be three hours difference, but there is only 2 due to Day Light Savings Time, then you can't simply subtract the two times at the same moment.