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[thegront]

I came to this forum is search of a an answer to a simple question: How does the position of the sun at sunset change during the year in terms of compass heading? Assume an unobstructed view of the horizon and being at about latitude 49 degrees north.

Thanks in advance for the help.

[stargazer]

The Sun changes position due to our rotation. remember we move 15 degrees every hour. If you were to keep track of the Sun each night you will see that the sun changes its position. Its only a few degrees a night. Try it and youwill see how it moves.


Becky

[Chicago Astronomer - Astro Joe]

Gront,

Thank you for registering as a member of the Chicago Astronomer and for your first post. Your inquiry is not only a basic fundamental question, but causes pause in all of us...as we need to think about the mechanics of solar progression.

It was noticed since earliest times that the Sun rose and fell at different points along the horizon at different times of the year. This is due to the Earth being tilted at 23 1/2 degrees on it's axis and along with our oval orbit, causes this apparent phenomenon.

In the Northern Hemisphere where we are at, the Sun either rises more to the North in the Summer or more toward the South in the winter.

The more North the sun rises, the higher and longer it is in our sky, and ergo...longer days of summer. Just the opposite is true during the winter months...lower Sun in the South equals shorter days. And as we travel along our ecliptic path around the Sun, the Sun also travels along our horizon in direct proportions.

At 49 degrees North, it places you at around the Washington State latitude where the sun get's even lower in the sky than it does here in Chicago, (42 degrees).

I always found it quite interesting that in our coldest months in the northern hemisphere, the Earth's north pole is facing closer to the Sun, than it is during the hot summer months.

I enjoyed responding to your inquiry, as it makes me rethink about why my heating bills are increasing right about now.

Blame it on the Tilt.

[stargazer]

I forgot to mention that I have been drawing out the sunspots now since before Astrofest in Sept. I used to be able to set up my scope right in font of the house in front of the car. Now when I go out there to do the drawing I have to go across the street. With no protection from the crazy drivers here. I think I have like 60 drawings of the Sun. I started it for the cert but found out it was fun so I stayed with it. I try to go out every day that I can. Try doing the sunspot drawing and you will see how the sun moves everyday.

Becky

[Al Degutis]

The Ecliptic, the path of the Sun, caught my attention this year now that I'm living in a rural area. As I drive through country roads, passing open farm fields, I've noticed the sunrises and sunsets a lot more, especially its position. I spent sometime looking at the ecliptic using my Pocket Stars PDA astronomy software (a good value at $20; same price for the PC version) and was shocked that I never realized how much of a shift from Northeast to Southeast the sun rises throughout the year.

Although Joe provided a very good visual illustrations, here's another way to look at it:

The following is based on my latitude of 42.33.
Using North on the compass as 0 degree azimuth, East as 90 degrees azimuth, South as 180 degrees azimuth:

• This morning (11/15/2004) the Sun rose at around 117 degrees azimuth which is basically southeast on the compass
  
• Yet 5 months ago (6/15/2004) it rose at 60 degrees azimuth which would be close to northeast on the compass
  
• On December 21, 2004 it will rise at 117.90 degrees azimuth

Unfortunately you can't just add 2 degrees to these numbers to get the approximate azimuth for your latitude. Even though 119 degrees (117+2) works for today it wouldn't for June 15th when the Sun rose around 53 degrees by you.

Hope this helped.

Pocket Stars software: www.nomadelectronics.com/

[Chicago Astronomer - Astro Joe]

Al,

What Al states is quite true and accurate. And with an ordinary magnetic compass, quite fun to track the sun a few days apart. If I had unobstructed horizon, I would place a stake into the ground each day, and follow the sun along it's travel.

Was that the program you were using during the Star Party, and showed me on your PDA? Quite cool! With a program like that, it certainly makes charting the sun easy. When I grow up, I wanna get one just like that. I see that they also have it for cell phones too!

What I dig about the site you mention, is that "Spock" highly recommends the software...

LMAO ;D

and Beck's...

Are you inside a race track oval? I know that most people shouldn't be behind the wheel, but their driving habits, (or lack of), interfere with your studies that much? What about going to the back of the house?

The furtherment of astronomy will not be curtailed by crazed drivers!

[Centaur]

Joe --

That was a fine explanation, especially with the graphical presentation.

However, you said, "I always found it quite interesting that in our coldest months in the northern hemisphere, the Earth's north pole is facing closer to the Sun, than it is during the hot summer months."

Actually, the Earth's north pole is tilted away from the Sun and the south pole is tilted toward the Sun at the time of the December Solstice. I believe you actually meant to make reference to the fact that the entire Earth is nearest to the Sun in January (perihelion) and farthest away in July (aphelion).

-- Curt

[Chicago Astronomer - Astro Joe]

Now Curt...

You are so correct...do you have a mind reading machine? I'm going to start to wear my aluminum hat again!

Yes, that is exactly what I ment...D'oh!

As a kid and with a child's mentality, I was puzzled on why it was colder when the earth was closer.

Thanks for the back-up!

No more answering posts while watching tv.

[NatureDevil]

The guys who originally built Stonehedge figured out the same things that we are talking about here without the use of pocket PC's and computer software.

Really makes you appreciate those bastards. I wrote a song about the ancients and their brilliance, and the effects we see today from it, called "What You Leave Behind."

NatureDevil

[Centaur]

thegront --

Welcome to the forum.

Joe did a great job helping you with his graphics. Someone noted the effect of the daily rotation of the Earth. Within the context of your question, it is actually the annual revolution of the Earth around the Sun in association with the Earth's axial tilt that produces the changes. The Sun appears to move about one degree per day against the starry background.

For those at all locations, the Sun rises near due east and sets near due west at the the time of both equinoxes. For an observer at 49 North, at the time of the Summer Solstice the Sun will rise/set about 39 degrees north of the east/west point. At local true noon it will appear near an altitude or 64 degrees. At the time of the Winter Solstice, the Sun will rise/set about 36 degrees south of the east/west point. At local true noon it will appear near an altitude of 18 degrees.

-- Curt

[thegront]

Thanks to all of you for the thorough, easy, and fun responses. I now have a clear picture of how that lucky old sun appears to behave relative to us.

[Chicago Astronomer - Astro Joe]

Gront,

An apparently simple question like the Sun's movement is in fact quite complicated and example of understanding basic celestial mechanics. At times, we all need to slow down about string theory, quantum physics and x-ray emissions, and behold the beauty of simple rotation and it's perceptive effect.

What's cool here is that we attempt to fill in all of the spaces together with good data and have fun with it.

No Extra Charge.