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The Academics Thread


Pariah

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The problem with scale models of the solar system is the disparity between the sizes of objects in the distances between them. If the stars and planets are represented large enough to be seen, the distance between them is impractical, in most cases. On the other hand, if the distances are set up to any kind of reasonable scale, then the Sun and planets become microscopic in size.

 

This is really the only model I'm aware of that shows both the sizes of the objects and the distances between them to the correct scale:

 

If the Moon Were Only 1 Pixel

 

Warning: The descriptor "A tediously accurate scale model of the solar system" is spot on.

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Unfortunately, the scale is what makes clear things like why we don't have eclipses every month.  The planes of Earth's and Moon's orbits are tilted with respect to each other by only a few degrees, but the Moon and Earth are separated by more than 30 Earth diameters.  Getting things lined up closely enough so that the shadow of one falls on the other is ... difficult.  And, the Earth-Sun distance is about 107 Sun diameters.

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On the first day of our astronomy class this summer, the professor had us break into small groups and gave each group a 6-inch picture of the Earth and another picture of the Moon at the same scale, and then invited us to go out in the hall and put them the proper distance apart. It was interesting to see what people came up with, and how.

 

I suppose that's the first lesson we learned in that class: Compared to the distances between them, objects in the universe are really, really tiny.

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No, at some point stuff just stops working, if only because of accumulated radiation damage.  And stationary landers on Mars may get coated with dust.  Burial is unlikely (unless you're near one of the poles), though.

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In between taking care of the dietary and sanitary needs of two children today, I've spent most of the day unpacking the state physics core curriculum. It's been an interesting process. I have, or at least I'm starting to get, some idea of how I'm going to teach all of this in just over a month.

 

Once I'm done with the unpacking process, the next step is to look at the district curriculum map and see what it has to say about order and pacing. The order in the state physics core is fairly logical and intuitive (which, frankly, is a refreshing change after having dealt with the chemistry core curriculum for the last 9 years). With luck, that means the implementation at the district level will also be fairly logical and intuitive.

 

I suppose we'll see.

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16 hours ago, L. Marcus said:

"In space the difference between huge and tiny is, comparatively speaking, very small."

 

Don't make us have to leave you at the center of a dead planet buried alive.

 

"Hey Kirk, who was the guy who liked doing that to people?"

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On 7/12/2018 at 8:09 AM, Pariah said:

I suppose that's the first lesson we learned in that class: Compared to the distances between them, objects in the universe are really, really tiny.

 

That's true for stars in our part of the Galaxy.  Galaxies, on the other hand, are relatively close to each other in comparison to their sizes.

 

A back-of-the-envelope calculation is a good homework problem for this.  Use the ratio (distance between object and nearest neighbor of the same type) / (radius of typical object of that type); the students need to look up (or work out) estimates for those.  Candidates to compare are stars in the Solar Neighborhood, galaxies in a cluster, gas molecules at STP, electrons in an atom, and protons in a nucleus, and quarks in a proton.  I think stars are the most isolated things when looked at in this way, but it's been a while since I thought about it in this way.

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