Sun still sinking south ?

[Jim Carlock]

Anyone else notice that the sun is still sinking south ?

I was thinking that the sun reached it's highest point in July and would start moving the other way in the sky. In June, the sun moved across the sky in a more northerly plane. In May it was even further north. In September the plane it's skewing along on is still moving south. I'm noticing this because I'm watching the shadows of the overhang of the roof and the shadows are indicating the sun is still moving in a southerly direction.

What's wrong with my thinking? I was thinking it would reach it's peak in July or maybe August (when it reached it's highest point) and then the shadows would start moving in the other direction. The side of the house that I'm watching the shadows on is the south side. I'm in Tampa, FL, and for some reason it's stuck in my head that the sun should start to travel a plane that is more northerly each day.

[Jim Carlock]

I was wrong in the way I was thinking. I found a site explaining the vernal equinox as being the a day when the length of night is equal to the length of day. And it occurs around March 21st every year. The summer solstice happens around June 22nd each year. For some reason I was thinking along the lines that August being the hottest days of the year represented the month that the longest day of the year occured. I'm starting to think now that August is hottest because the summer gradually warms the ground and the rise in temp is felt because of the heat already being in the ground. I'm not sure this is correct and proper thinking, but the more I think about it... I think the temp is low enough to not start slowing its rise in temp each day.

So the way it looks, it'll be about September 21st or 22nd where the sun will start making it's northerly track again. That represents the autumnal equinox. On this day the day will be equal in length to the night.

Thanks Jackie.

[Scott Anderson]

...

[J. Kolenovsky]

Scott Anderson got it right. See his reply.

J

Jim Carlock wrote:

[Jim Carlock]

Boy, I'm way off in thinking that the sun travels along the equator and the position of the earth is what is changing. I've got to rethink everything and start reading more stuff on this topic. It's been ages since I've looked into this... Well here goes...

For some reason I was under the impression that the earth rotated on an axis and that as the earth rotated around the sun, that the equator represented the closest part of the earth to the sun. This means that North Pole represents one point of the axis and the South Pole represents the the other point of the axis. The axis does not noticeably change, but I'm thinking that it does change and would be noticeable if you could live 1000 or maybe 10,000 years.

Okay, my question is this... if you live on the equator, are the days and nights equal every day of the year?

the sun is always directly above the equator, and the equator represents the closest portion of the earth to the sun, how does the sun cross the equator? You lost me with your statement. I think you meant to say something else.

link above indicates that the longest day of the year falls on or about June 22 (at least for the northern hemisphere). It should be December 22 for the southern hemisphere. So with Dec 22 being the longest day for the southern hemisphere and Dec 22 being the shortest day for the northern hemisphere... does any of this matter on the equator, being that on the equator, you'd get 12 hours of day and 12 hours of night each and every day of the year, because you'd be on the closest spot on earth to the sun, each and every day of the year, not taking mountains and depressions into consideration.

Being that the earth rotates on an axis, the autumnal equinox I think is going to vary slightly for every every position away from the equator? I think that's the lattitude.

There is a great link here that talks about how the distance of the earth from the sun never goes past 3% or 4% and states that the earth is more circular in orbit than elliptical. I used to think that the distance from the sun is what caused seasons when I was a kid. That's not true. The link below indicates that the earth is farthest from the sun on or about July 4th. Very interesting coincidence!

for the comment, I think I know what you're trying to say, but you are just not saying it correctly. ;-)

[Gardñ]

the earth revolves around the sun once per year (imagine a circle around the sun). the earth also rotates on it's axis (the Poles) once per day. [fast] But this axis is not perpendicular to the 'circle' of earth's orbit around the sun. so...

visualize that the circular around the sun is "horizontal". lets choose our vantage along this circle so that the earth's axis is now tilted at one extreme when we see the earth at the leftmost position on this circle. And lets say that teh north pole is tilted toward the sun. (therefore teh south pole is tilted away from teh sun)

visualize those fast daily revolutoins. notice that teh top of the earth (north) is predominantly exposed to sunlight. It's summer. :-)

eventaully, 6 months later, the earth is on the oppostie side of it's orbit (but it's axis ALWAYS remains tilted exactly same angle) So now the south pole sees a lot of sunlight. and so, it's winter

the equator. visualize your self at one dot on the equator. say you're on the nightitnme side of earth. as earth rotates to give you dawn, you swing around and i think you see the sun from your south. you should see it from the south all day.

6 mo later you should see the sun from the north (all day)

[Scott Anderson]

Yes, days and nights are always the same (almost) on the equator. But the sun is not always directly overhead on the equator. It's only directly overhead on the spring and autumn equinoxes. Any other time it appears to be swinging north and south between the tropics.

Technically, the earth and sun really aren't tilting north and south each year. The earth rotates at an angle relative to the plane of it's orbit. The poles don't rotate around the sun, rather they stay pointed in the same direction, no matter where the earth is in it's orbit. In June, the north pole is pointed a little bit towards the sun and it's the northern hemisphere that gets longer days. In December, the Earth has gone 180 degrees around it's orbit, but because the poles don't rotate, they are still pointed in the same direction and now the south pole is pointed towards the sun and it's the southern hemisphere that gets longer days. From the point of view of an observer on the earth, this causes the path of the sun to swing north and south over the course of the year as the planet swings around it's orbit. There's an illustration of this here:

an explanation here:

...

[Salty Thumb]

"Jim Carlock" wrote in news:svQZc.7263$Of3.7205 @tornado.tampabay.rr.com:

The earth does rotate on an axis, and the axis does wobble a bit (I think the wobble is called precession or procession or something like that). The band perpendicular to the axis of rotation and intersecting the earth's center is the equator. Meanwhile the earth is orbiting the sun. The orbital plane is tilted something like 23.5 degrees from the plane of the equator or rotational plane. The orbital plane is also known as the plane of the ecliptic.

close in duration at the equator. Atmospheric effects aside, for the sake of argument say a day is exactly 24 hours. This means the earth makes a

360 degree rotation in 24 hours. However, at same time, the earth is moving in an elliptical orbit that isn't parallel to the plane of rotation.

I don't think the first two are true, but I'm too tired to think about it. The sun crosses the equator because the plane of the eclipitic is not parallel to the earth's rotational plane.

You get your equinoxes when the plane of the ecliptic intersects the rotational plane, i.e. when the difference is 0 degrees. At the points where the earth is at +/- 23.5 degrees you get your solistices.

At the "astronomical" distances involved, saying the orbit is nearly circular is only useful for lay people with nothing to quibble about. At any rate if you are talking about the 'closest point', and you're saying the orbit is circular, then all points are relatively equidistant.

Congress decided "man it's too hot for this, let's declare independence and get out of here." Conspiratorically, it makes sense, Ben Franklin and TJ more likely than not knowing about such things picked the day the earth was farthest away to declare being farthest away from England, i.e. independent.

[gregpresley]

[J. Kolenovsky]

Scott, thank you for the 2 excellent links explaining this. Especially

as a visual one.

J =

[J. Del Col]

So you slept through astronomy 101?

J. Del Col

[Jim Carlock]

Thanks... I see where my line of thinking was slightly off.

I will still argue that the sun does not move over the equator. :-)

I can see where my line of thinking was wrong about the equator being the closest point. I just can't pinpoint or explain it right at the moment. I'm currently not seeing the equator as being a plane perpendicular to the axis of rotation.

I do see the northern hemisphere getting closer to the sun during the summer, thus producing summer in June/July/Aug.

I see the southern hemisphere getting closer to the sun during our winter months.

So I'm imagining the earth's spin now, on a 23 degree axis... but I ask myself 23 degrees from what, and I'm I start to form a plane that involves the earths yearly revolving. And the 23 degrees must be in relation to that plane, and simplifying it to exclude minor nuisances where the earth wobbles off of that plane. I'm not sure that this is correct, but it's what I'm working off of right at the moment...

But this is leading along the lines that direct east is visible when you are on the equator and you watch the sun start to rise. That would be east. West being the point at which the sun sets on the equator. Anywhere else in the northern or southern hemispheres, the direction of rising and setting is not directly east, but would be southeasterly if it's summer and you're in the northern hemisphere and then northeasterly in the winter for the same location... My imagination starts to fail... but I think that's more proper than saying that the sun moves over the equator... providing it's correct.

It's not the sun that is moving over the equator, it's the plane of the equator, which is created by the spin of the earth that is shifting in relation to the sun... ???

Now moving along in this line of thinking... there are seasons when you are in the northern hemisphere and there are seasons when you are in the southern hemisphere... but if you are on the equator, there are no seasons. :-) I think that is correct. Taking out all the extraneous variables, it would be correct to state that days are equal in length to the nights on the equator at any given instant of the year. And I'm drawing the equator in this manner. Salty Thumb explained the equator as being perpendicular to the axis that the earth rotates upon. I'm having problems seeing it in this fashion and it's easier for me to view it by thinking of it in relation to the lengths of day and night being equal. And while there is a vernal equinox and an autumnal equinox where the length of the day is the same as the length of the night (and this only happens if you are NOT on the equator), those represent the exceptions to the rule about the equator. Because for two days of the year, there is that exception to the rule about the equators position. So if you change the rule to read that the equator is drawn if the previous day was equal in length to the previous night's duration, there you will get a more substantial equation for drawing the equator. I could be wrong but my beautiful world will be destroyed if I am .

And I keep asking myself what is the signifigance of the length of the days being equal to length of the nights all year long... and what initially jumps into my head is that the earth is closest to the sun at that point, and a few things run through my head... where I throw that idea out and several other ideas run through my head... along the lines that if that position on the earth is closest to the sun at let's say 12o'clock high noon at that position on the earth... this could account for the longer days in the northern hemisphere. It's throwing my head through some loops though... LOL

I've thought too much on it and I have to get some other stuff done... it's been a pleasure thinking about it and I've got a much better grasp on why the sun is sinking south.

Thanks to everyone! And I will argue with Scott (et al) that the sun is not the thing moving that is causing the sun to sink south. ;-) I can see where it can be thought of as such in an abstract kind of way, and I now know where my a couple of my ideas were a little off... and perhaps some of them still are... I have to stop thinking about for now though.

[Spud Demon]

"Jim Carlock" writes in article dated Fri, 03 Sep 2004 02:18:00 GMT:

It isn't. The Earth revolves around an axis that goes through the Sun. The Earth rotates around a a different axis that goes through the north and south poles. If these 2 axes were parallel, the Sun would appear to be always above the equator, but they aren't. They differ by about 23 degrees.

It's not the distance to the sun that's important but the angle that the light hits the earth. The closer you get to perpendicular, the more light per unit area you get. Even though the equator gets only 12 hours of daylight, on the equinox it is more intense than on the solistice.

The distance from the equator is proportional to the latitude, but the equinox is a single moment that happens twice a year.

about when I read the subject -- is where the sun sets. If you're north of the tropic of cancer, the sun will appear to be south of you at high noon every day. But not at sunset! During the summer, the sun can set in the northwest. The pathological case of this is if you're on the Arctic circle on June 21, the sun appears to bump the horizon (set and then rise) at midnight. And it bumps it in a spot due north of you!

-- spud_demon -at- thundermaker.net The above may not (yet) represent the opinions of my employer.

[Warren]

Wait a minute. Are you guys saying that Earth isn't flat?

[Gardñ]

"Jim Carlock" in news:0C%Zc.7359$Of3.4509 @tornado.tampabay.rr.com:

get a ball. put a 'belt' of masking tape around it. emulate th motion of the earth.

[Gardñ]

"gregpresley" in news: [e-mail]:

but republicans are sure that hilary did it.

[J. Davidson]

[omi]

[Bob Chipeska]

Astronomy 101? This is junior high stuff. Sorry, but why are seasons a mystery to adults? I mean really. I can see a primitive tribe in the Amazon not understanding this, but educated adults?

[J. Del Col]

The natives of Amazonia would be far more in tune with the seasons than the "educated" adults. They might not understand why things happened, but they could tell you exactly when they would.

J. Del Col