What makes sunrise and sunset times?
Jan. 18th, 2010 04:29 pmOh, don't give me "earth's rotation" and "angle of the sun", I know that! But...
Look, I googled to find what time sunset was in NYC, found out that today it's 4:55. Sunrise was at 7:17 Okay, fine.
But in Anchorage it's sunrise at 9:52, but sunset only at 4:27. The sun rises two hours later there, but it only sets about thirty minutes earlier? I'd always assumed it was constant - if it rises an hour later, it sets an hour earlier, that sort of thing. And over in Honalulu the sun rose at 7:12 (barely earlier than here in NYC) but it doesn't set until 6:12. Maybe my problem is in viewing my own city as the default, and if I viewed these times as varying from the equator (or the North Pole) they'd make sense? I understand that summer and winter are more dramatic closer to the poles, and less dramatic close to the equator, but... like I said, I thought you took from both sides of noon more or less evenly wherever you were.
Look, I googled to find what time sunset was in NYC, found out that today it's 4:55. Sunrise was at 7:17 Okay, fine.
But in Anchorage it's sunrise at 9:52, but sunset only at 4:27. The sun rises two hours later there, but it only sets about thirty minutes earlier? I'd always assumed it was constant - if it rises an hour later, it sets an hour earlier, that sort of thing. And over in Honalulu the sun rose at 7:12 (barely earlier than here in NYC) but it doesn't set until 6:12. Maybe my problem is in viewing my own city as the default, and if I viewed these times as varying from the equator (or the North Pole) they'd make sense? I understand that summer and winter are more dramatic closer to the poles, and less dramatic close to the equator, but... like I said, I thought you took from both sides of noon more or less evenly wherever you were.
What is a day?
Date: 2010-01-19 05:01 am (UTC)A day is not really 24 hours. It is actually a bit longer. Just like the Earth's rotation around the sun is not a true 365 days. We have to round things out to whole numbers for our feeble minds to comprehend or end up frustrated trying to figure out the exact time of day.
That extra day every four years compensates for a lot.
On a side note, I am not a LiveJournal user and haven't taken the time to figure out what an OpenID is so I just leave my posts in the default position. But if you must have a name for this occasional reader.
A Smith
Another side note, ever wonder why there are two words in those sign in verification things at the bottom of the reply section? I know, just wondering if a curious person like yourself has ever thought about it.
Re: What is a day?
Date: 2010-01-19 05:04 am (UTC)Open ID is a... um... thingy set up by LJ so that if you use one of a variety of blogging services (or just like to post with a verified identity at blogs you read) you can use the same username everywhere and people know it's *you* and not somebody cannily pretending to *be* you.
To tell the truth, it's easy enough to see if you're being faked by most trolls, because most trolls are stupid in a few very important ways, but it's always nice to have a name to peg on to somebody. I can't explain it, but true anonymice are creepy. (And often spam, but that's beside the point.)
You think the discrepancy between the clock day/year and the actual length of the day/year is part of this?
Re: What is a day?
Date: 2010-01-20 05:10 pm (UTC)It gets even worst when you hear about how shockwaves from large volcanic eruptions, earthquakes and even atomic bombs have apparently shifted the planets axis.
Oh, and with those two word verification things... One word is a known word, a control word if you will, while the other is a word scanned in from a book that the computer cannot read properly because the print or page has been disrupted by creases, stains, etc... So the guy who created this verification system is also in charge of scanning in all these books for archiving, and instead of trying to fix all the unintelligible words with a small group of people he has enlisted all of us who use his verification system to help him one word at a time, assuming the human brain is able to read and understand what these distorted words are better than a computer.
I just thought you would get a kick knowing that everyone who replies to your postings is helping to restore a lost piece of literature, thus, you with every one of your postings is saving a book. How cool is that?
Re: What is a day?
Date: 2010-01-20 05:22 pm (UTC)No, the moon is on the order of one light *second* away. 8 minutes is about right for earth–sun.
a calendar and clock systems which we correct for every four years.
The calendar we correct every four years; the clocks we correct irregularly, with leap seconds. (For a while, leap seconds were inserted about every 18 months, but then there was a pretty long "dry spell".)
everyone who replies to your postings is helping to restore a lost piece of literature
Those CAPTCHAs are just shown to anonymous commenters; users with a LiveJournal account aren't shown one. (At least, this is my guess; it could also be that I don't see one because I'm on her friends list, but it seems more likely to turn on CAPTCHAs only for anonymous comments, not for all non-friend comments.)
Re: What is a day?
Date: 2010-01-22 05:20 am (UTC)Re: What is a day?
Date: 2010-01-22 05:47 am (UTC)Re: What is a day?
Date: 2010-01-22 05:51 am (UTC)Re: What is a day?
Date: 2010-01-22 05:51 am (UTC)Re: What is a day?
Date: 2010-01-22 05:54 am (UTC)Re: What is a day?
Date: 2010-01-22 05:58 am (UTC)