# Thread: Physical Astronomy Quiz - Which direction is the Sun at midnight?

1. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

I assume we're ignoring daylight savings time. But the Sun is not actually overhead (or as close to overhead as it gets at your location -- i.e., at the meridian) at noon and underfoot at midnight. Because the Earth follows an elliptical path, from the Sun's viewpoint the Earth is moving faster (in angular speed) at some times of the year and slower at others. That means the time when the Sun is overhead or underfoot is a bit off of noon and midnight (and hence will appear somewhat to the east or west).

But I think for purposes of a quiz for the general public it is safe to ignore this sort of thing. For those appreciably north of 23.5 degree latitude, the Sun would lie to the south at noon and to the north at midnight. I assume that was the answer you were looking for?

2. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

I used a computer to show me where the sun is, i think you'll need at least some help from other sources to make the question practical/interesting.basicly if the sun is high in the sky north at midday then where must it be at midnight on the other side of the earth from where you are, south ?

If the sun is nw in the sky at midday,then where should it be at midnight, se ? i think that might be a suitable idea of an answer/question in relation to where objects are in a 24/hr night day period.

3. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

I'd like to show students moon phases and ask them questions why the moon does that, and maybe could show them relation where the moon is at with the earth and the reflecting light from the sun to the moon.i think that could be a nice planetary model with questions/answers. could someone put that in a simple math equation ?

I think maths and astronomy should mix in schools,heck with accounting.

4. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

If one were standing on the South Pole today, the Sun would always be above the horizon an to the North.

Scott

5. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

Originally Posted by MG1692
If you live close to the equator. The sun in Feb will be still east of the meridian.
Ah! Are you talking about the Equation of Time: the Sun does not actually reach zenith at clock noon every day? I had not really accounted for that level of analysis - but this strikes me as a nice entry point to that complex subject.

Thanks for pointing that out!

Also, I think I get what you are highlighting about being at the Equator. In fact, I think that if you could look directly through the Earth to the Sun at midnight, you might call the direction "down" rather than give it a cardinal name.

Really great feedback MG1692! I'll be refining the question based on this discussion.

6. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

Originally Posted by Voyageur
Who is this question intended for? You say "the general population," but that is a pretty broad category of learner/thinker! Some of the general population believe that the Earth is flat...
That is true. I suppose my target audience is 5-8th grade (10-14 years old). Plus the educated, rational adults who belong to the kids.

Originally Posted by Voyageur
Open-ended questions are a great way to stimulate curiosity and thinking, but the acceptable degree of ambiguity depends on the age of the learner. if the question is too ambiguous, that's just frustrating for young learners who may not yet have the cognitive skills to reason at that level. Using the Piagetian model, a child at the concrete operational stage is probably only capable of answering the question exactly as initially worded, "If YOU..." and will only consider his or her own location on Earth at that time. He or she won't initially consider it in the abstract. In fact, I think you'd find that even some early college-aged students would have trouble approaching the question in its most ambiguous form without some prompting.
Great point Voyageur! Given the age group, I think I will anchor the question to "Based on where you are now..."

Originally Posted by Voyageur
But even with a literal interpretation, how will students visualize this exact location? Do they have a well-developed mental model of the Earth's rotation and orbit? It would be interesting to ask even this simple question, "Why is it colder in winter than in summer?" I'll bet you'd get a lot of people--adults, not just kids-- saying that it's colder in winter because the Earth is much farther from the Sun in winter than in summer.
Yes, the intent of this question is to help figure out how well-developed the "Earth rotation and orbit mental model" is and if they can use it to reason about the various motions and positions that go into determining the answer.

I like the socratic dialog approach - I've used it to good effect in a few presentations.

Originally Posted by Voyageur
If I were going to explore your question with young students, I would want to have a globe and something to represent the Sun. Once I had a good discussion of the answer for the literal here and now, I'd prompt students to think beyond that to consider how observers on other parts of Earth would respond. I can envision having a lot of fun with it, e.g. "OK, but what if you are a polar bear in its natural habitat?" A koala? A three-toed sloth?"

Anyway, I always get carried away with science education stuff!
Thanks for the feedback about providing the proper context and building up the foundation first. That will definitely help ground this mind expanding exercise.

Much appreciated.

7. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

Originally Posted by Mark Moyer
I assume we're ignoring daylight savings time. But the Sun is not actually overhead (or as close to overhead as it gets at your location -- i.e., at the meridian) at noon and underfoot at midnight. Because the Earth follows an elliptical path, from the Sun's viewpoint the Earth is moving faster (in angular speed) at some times of the year and slower at others. That means the time when the Sun is overhead or underfoot is a bit off of noon and midnight (and hence will appear somewhat to the east or west).

But I think for purposes of a quiz for the general public it is safe to ignore this sort of thing. For those appreciably north of 23.5 degree latitude, the Sun would lie to the south at noon and to the north at midnight. I assume that was the answer you were looking for?
Yes! Ignoring daylight savings. (I'd better put that in the set up for the question). I think the equation of time is a deep subject that touches on so many aspects of physical astronomy that it deserves its own quiz.

Yes, that was the intended "general population" answer... I am in the northern hemisphere so I would see the Sun in the south at noon, north at midnight.

Thank you for the feedback Mark!
Last edited by StarInAStar; 02-14-2018 at 10:44 PM.

8. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

Originally Posted by StarInAStar
Ah! Are you talking about the Equation of Time: the Sun does not actually reach zenith at clock noon every day? I had not really accounted for that level of analysis - but this strikes me as a nice entry point to that complex subject.
Correct. The Sun will reach the zenith at the mid point of the length of day, not by the clock. So if you have a 10 hour day or a 14 hour day. The Sun will be at the the zenith after 5 hours or 7 hours respectively.

In the southern hemisphere this was pretty important back in the day when trying to use an equatorial telescope. Because we have no bright pole star the only way you could get a decent south celestial bearing was to hammer a stick in the ground. Find out the time of the Sun reaches the meridian and then measure the direction of the shadow being cast.

You can use the same trick for observing Venus in daylight. Find what time Venus crosses the Meridian. Look due south or North (depending on the hemisphere) and you cant help but see it

9. ## The Following User Says Thank You to MG1692 For This Useful Post:

StarInAStar (02-14-2018)

10. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

Originally Posted by MG1692
You can use the same trick for observing Venus in daylight. Find what time Venus crosses the Meridian. Look due south or North (depending on the hemisphere) and you cant help but see it
Now that is a cool trick I have to try!

11. ## Re: Physical Astronomy Quiz - Which direction is the Sun at midnight?

Originally Posted by yobbo89
I used a computer to show me where the sun is.
yobbo89! I followed your lead here and fired up stellarium (a real gift to humanity) and placed myself at the equator and ran through some simulations jumping time by day and week.

I have to agree that the question as posed is not quite "practical." The goal is to stir the imagination and provide a thinking platform for the gross physical motions. I think the motions and positions of sky objects at the equator and in the polar circles is not really suitable subject matter for a "general population" question. Those interesting wobbles at the equator however, are good thought provoking stuff for an advancing astronomer at the high school or college level.

Here is my reconstructed question based on everyone's feedback (the detail is overwhelming the question so I am looking for a way to trim it out):

Let's assume that your location on the Earth is somewhere between the Tropics and the Arctic/Antarctic circles (Tropic of Cancer to Arctic circle/Tropic of Capricorn to Antarctic Circle). From where you are now if - at the exact moment the night is half over - you could view the Sun through the Earth, which cardinal direction would you be facing? East, West, North, or South?

The phrasing seems awkward... does anyone have any suggestions for tightening that up?

Thank you everyone!
Last edited by StarInAStar; 02-15-2018 at 02:03 AM.

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