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

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

Here is a Quiz I made to test a student's ability to reason about cardinal direction with respect to meridian and time. I would like some help testing how it plays out with expert astronomers. You all have years of sky observation so I want to know what you think before I try it out on a general population. I welcome any and all observation and feedback.

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If you could see the Sun at midnight - by looking through the Earth - which cardinal direction would you be facing?

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

What time of year?

What is the exact location of the observer?

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

Great questions MG1692!

Any time of year.

Exact location is up to you.

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

Originally Posted by StarInAStar
Great questions MG1692!

Any time of year.

Exact location is up to you.
Well unfortunately then your question becomes nonsensical. There are circumstances were the answer can be any of the cardinal points depending on location and time of year.

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

I think he's getting at the anti-Meridian - which is (I think) always north - based on the Meridian being to the south - in the north latitudes. But since the earth is between the observer and the Sun you can't see it as we're on the dark side of the earth. This only applies to observers in latitudes north of the Sun, of course. But since the earth is tilted on it's axis the actual latitude of the noon/midnight Meridian changes daily. (Which also happens to be why you can get an estimated position at the noon Meridian using celestial navigation.) I'd say that if you want a correct answer you definitely need to say something like "to an observer in Indianapolis..."

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

given my lat long,date, the sun is south

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

Originally Posted by MG1692
Well unfortunately then your question becomes nonsensical. There are circumstances were the answer can be any of the cardinal points depending on location and time of year.
Thanks for the comment! This is really helpful in refining the question to make it correct and fun.

I am curious about how could the answer be "any of the cardinal points" ...

Also, MG1692, could you elaborate on how the time of year would affect the answer.

The observer's position in either the northern or southern hemispheres would affect the answer and that's part of the quiz - it's kind of a trick question in that it forces you to realize the question is incomplete and establish your own position first in the answer.

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

I think he's getting at the anti-Meridian ... I'd say that if you want a correct answer you definitely need to say something like "to an observer in Indianapolis..."
Hi Star Dad! Thanks for sharing the "think through" with me. I am grateful for your help.

The main thing the quiz is supposed to do is encourage you to think geometrically about the physical relationships that produce sky motions and clock time.

So, it's not the anti meridian I was trying for (which is the opposite of the prime meridian) but the local meridian (the line through zenith from due south to due north).

I think you are right about the "to an observer in Indianapolis..." that it would make the question have exactly one answer. However, I like the ambiguity that the lack of definite position gives - especially for our friends who observe the southern hemisphere skies.

yobbo89 has offered a suitable approach - I think I'll modify the question so it defines the observer's location as "observing at midnight from where you are now...":
given my lat long,date, the sun is south

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

Originally Posted by StarInAStar
Thanks for the comment! This is really helpful in refining the question to make it correct and fun.

I am curious about how could the answer be "any of the cardinal points" ...

Also, MG1692, could you elaborate on how the time of year would affect the answer.

The observer's position in either the northern or southern hemispheres would affect the answer and that's part of the quiz - it's kind of a trick question in that it forces you to realize the question is incomplete and establish your own position first in the answer.
If you live close to the equator. The sun in Feb will be still east of the meridian. Which depending how pedantic you are being would make it west of the meridian to an observer at midnight.

If you live between the Tropic of Cancer and Capricorn the answer is similarly fluid. Again depending on the time of year.

Then as you move towards the Arctic circle, there are days (late Dec early Jan) when the sun is very low in the east. The reverse would be applicable in the south.

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

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...

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.

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.

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!

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