General Question

Yellowdog's avatar

At the Spring and Autumnal solstices, are the sunrises perfectly eastward and the sunsets perfectly westward, night and day equal, all over the world?

Asked by Yellowdog (6780points) 2 weeks ago

I know that the days get more long the further north you go as we progress toward summer, until you get white nights and eventually 24 hour sunlight at and beyond the arctic circle.

Daylight Savings time and the lengthening of days in the Spring are making me think about all this.

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7 Answers

Zissou's avatar

You mean the sun rises at exactly true E on the compass, and sets at true W? No. Day and night equal, all over the world? Yes.

Edit: I guess I was mistaken about the first part.

Yellowdog's avatar

Thanks. And I meant equinoxes, not solstices. Thanks.

Caravanfan's avatar

No on the first and yes on the second
Think of your other question on the south or north pole. Standing there on the equinox you would see the sun at the horizon circling you for 360 degrees.

LostInParadise's avatar

During the equinoxes, the sun appears directly overhead at noon along the equator and the sunrise and sunset will appear directly eastward and westward respectively. If you live within 23 degrees latitude of the equator, the same will hold true for one day of the year. For everyone else, the sun will always appear a little southward or northward.

Zissou's avatar

@Caravanfan @LostInParadise Thanks. I thought it was something like that, but when I checked my answer on that Stanford link, it was vague on that part of it.

Yellowdog's avatar

Pardon my stubbornity. I always hate it when people ( me, myself in this case) are too dense to accept perfectly good answers when they themselves asked a question. Why ASK if you disagree with the answers given.

But it still seems to me that everywhere East and West exist AT ALL, that the sun would rise in the exact east and set in the west on the equinox.

I know that when the sun first re-appears it would have to be a little short sunrise in the South, howbeit.

Even at the North Pole at the equinox, the sun would be BELOW the horizon UNTIL the Spring equinox and gradually would rise ABOVE the horizon at the spring equinox, going in circles following the horizon, and by midsummer reaching its highest arc. Then spiral down again as we pass midsummer and go below the horizon at the autumnal equinox., first disappearing in the south—gradually the place of sunset would move westward and rise eastward.

But since the sun is far away and not orbiting the Earth as the moon does, we’d still see a perfectly eastward sunrise and westward sunset at the spring and fall equinoxes, respectively. The sun would stay in the south but close to the horizon between that perfectly East and perfectly West point where it rises and sets below that Southern horizon,

I’m going to have to work this through until my brain is completely familiar with how it works.

LostInParadise's avatar

If you track the sun, you will see that it makes an arc in the southern portion of the sky. People talk about the advantage of having a southern exposure. I can say this because I know you live in the Northern Hemisphere more than 23 degrees latitude from the equator. In the winter the sun travels at a lower angle in the sky than in the summer. The sun never appears directly overhead, even during the summer solstice. All of this is reversed for those who live in the Southern Hemisphere below 23 degrees south. There is no way for the sun to suddenly face due east or due west.

I need to make a correction to what I said in the previous post. People within 23 degrees of the equator, except for those on the extreme ends, will have the sun pass directly overhead twice a year, an equal number of days before one equinox and after the other.

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