1964: Spatial Orientation

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Spatial Orientation

Title text: Here, if you know the number of days until the vernal equinox, I can point you to the theater using my pocket Stonehenge.

Explanation

This explanation may be incomplete or incorrect: The table needs extending to include each thing Cueball lists. If someone could clarify on the stonehenge... Also, link (more?) comics related to Cueball/Randall overthinking things. - Please change this comment when editing this page. Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks.

Location in space is always relative, as we cannot observe empty space itself and find an "absolute" location. There is so much going on in space, planets orbits and rotations etc. that it can be very hard to define an "absolute" location.

Frame of reference	Explanation
The Earth (rotation)	Cueball starts by stating that as he is facing west, the Earth's spin will be carrying him backwards.
The Earth (orbit)	Cueball then seemingly corrects himself in his head, having accounted for the fact that the Earth is also revolving around the sun.

Cueball internally attempts to orient himself amidst the galatic chaos but is confused and has to restart. It is then revealed to the reader, that some passersby were only trying to ask Cueball for directions to the theater, and he was just grossly overthinking it. (A recurring theme in xkcd. See: #222: Small Talk, #439: Thinking Ahead, #1643: Degrees). One can imagine Cueball having his mind in astrophysics so much that he needs to calculate the angle of the road relative to the plane of the galaxy to determine which way a destination is in conversational terms.

In the title text, Cueball mentions he has a pocket Stonehenge. During the equinoxes the sun lines up with the actual Stonehenge's pillars. Assuming you were at the actual monument, armed with the date you could calculate the cardinal directions based on the sun's location relative to the pillars.

Transcript

This transcript is incomplete. Please help editing it! Thanks.

[Cueball appears to be tilted on a flat surface.]

Cueball (thinking): I'm facing West so the Earth's spin is carrying me backward. But our orbit is carrying me forward around the Sun.

The Sun is passing over my left shoulder. I'm at 39ºN, so I'm tilted. But wait, Earth's axis is tilted by 23º. Do I add or subtract that to get the tilt of the Solar System?

Ok, I see the Moon. It follows the Sun's path, but is it moving toward it or away? I know it orbits counterclockwise from the North...

My head hurts. Let me start over.

Off-screen voice #1: He's just standing there. Hey, do you know which way the theater is or not?

Off-screen voice #2: Let's ask someone else.

[Caption below:]

I spend way too much time trying to work out my orientation relative to other stuff in the universe.

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Discussion

Dunno where to put this, but Captcha is giving a deprecation notice and asking to move to reCaptcha... Miguel Piedrafita 17:46, 7 March 2018 (UTC)

Someone better make a pocket stonehenge now. Linker (talk) 17:42, 7 March 2018 (UTC)

Aren't all those pocket whatsits running on silicon close enough?

Gene Wirchenko [email protected]

http://www.stonehengewatch.com/ Wonder if Randall saw this before the comic...Linker (talk) 14:16, 8 March 2018 (UTC)

http://www.iankitching.me.uk/humour/hippo/henge.html - the pocket Stonehenge made me think of this! If you want the audio, listen to the first track of https://www.youtube.com/watch?v=usdf8UHL0vU . 172.68.174.52 16:41, 8 March 2018 (UTC)

I would be remiss if I didn't mention that this comic was published two weeks before the vernal equinox 162.158.62.45 19:20, 7 March 2018 (UTC)

I started to nerd snipe myself as I tried to figure out that latitude/earth tilt thing. I have come to the conclusion that it depends on the time of year. He would be 39 degrees on the equinoxes, 16 degrees on the summer solstice, and 52 degrees on the winter solstice. I assume this is in relation to the solar system, but I know pretty much nothing about astrophysics, and I probably worded it all wrong in the first place.172.69.70.137 20:54, 7 March 2018 (UTC)

I guess it mainly depends on the hour of the day: for example, at 12:00 solar time of the spring equinox day, the tilt would be 16 degrees ; but because of the Earth rotation, 12 hours later, it would be at 52 degrees (or 128 degrees)... 172.68.46.143

Is there a category for overly thinking things? If not, should we create one? Herobrine (talk) 23:21, 7 March 2018 (UTC)

I don't think there is a category, but there is a word; "nerd-sniping" 108.162.216.208 01:12, 8 March 2018 (UTC)

Do you think #1917 would be relevant for this? 162.158.126.76 12:03, 8 March 2018 (UTC)

Yeah, someone (not me) should make one for it...Linker (talk) 14:13, 8 March 2018 (UTC)

A couple of weeks ago

I was doing this to figure out my relative motion to the plane of the galactic (without the latitude with respect to the moon part, and lying in bed so I wouldn't fall over).Cutech (talk) 08:10, 11 March 2018 (UTC)

Perhaps Cueball needs to go live with the Kuuk Thaayorre people of Cape York in Northern Queensland. These folks don't use egocentric directions, but use cardinal dirctions for everything: "There's an ant on your southeast leg"... A good discussion is found at < https://www.edge.org/conversation/how-does-our-language-shape-the-way-we-think >. 172.68.2.64 12:06, 8 March 2018 (UTC)

Hey, when you outright delete someone's contribution, it would be great if you'd include an explanation of the edit to help support the ego of the person who wrote it =) 172.68.54.148 12:16, 8 March 2018 (UTC)

The description asserts that Cueball was overthinking his attempt to direct the out of frame person to the theatre, but that really depends on where the theatre is. If the theatre is not on Earth Cueball's reasoning could be considered relatively simplistic. 162.158.154.43 15:54, 8 March 2018 (UTC)

Suppose we want to know what the angle is between Cueball and the solar plane on the day of the spring equinox, at the time when it is solar noon at the point on the equator directly south of Cueball. We can call this point on the equator A and call Cueball’s position C. By definition, the plane of the Earth’s orbit around the sun (which we are considering to be the same as the plane of the solar system) passes through the center of the Earth. It also, at this time, passes through point A. Now, there must be some point B that is the point on Earth’s surface that is closest to Cueball while lying on the solar plane. This point is NOT necessarily point A, which is the point on Earth’s surface that is the closest to Cueball while lying on the equatorial plane.

The angle between Cueball and the solar plane should basically equal the number of degrees between Cueball and point B. We can get a rough approximation for this using the Pythagorean theorem. The Pythagorean theorem is NOT valid on the surface of a sphere when dealing with large distances relative to the size of the sphere. That is, just because the shortest arc along the surface of the sphere from point A to point B on the sphere forms a right angle with the path from B to C at B, does NOT mean you can square the great circle distance from A to B and add it to the square of the great circle distance from B to C to get the great circle distance from A to C. Nonetheless, we can use the Pythagorean theorem to get a very rough approximation.

The “line segment” (actually an arc) along Earth’s surface between A and B lies along the solar plane, since A and B are both on the solar plane. Since shortest distances are found using a perpendicular, the arc from B to C is perpendicular to this. So, A, B, and C form a sort of right triangle on the surface of the Earth. The angle between AB and AC is equal to the Earth’s orbital tilt of about 23 degrees. The distance AC is 39 degrees (that is, 39/360 of the Earth’s circumference). Since AC is the hypotenuse, the cosine of 23.4 degrees must equal BC over AC, so BC equals cos(23.4 degrees) times 39. This yields 35.8 degrees, an approximation for the angle between Cueball and the solar plane. 108.162.216.190 22:30, 10 March 2018 (UTC)

So, is the angle that Cueball is standing in the comic relative to the orientation of my monitor realistic for the angle that he's standing relative to Earth's orbital plane as described or not? davidgro (talk) 01:12, 27 March 2018 (UTC)

Okay, this explanation is ridiculously long, and explains like everything, how is it still incomplete? You can add the tag again if you want, but I think it's complete. Herobrine (talk) 07:02, 8 April 2018 (UTC)

Would it be worth mentioning that 39 degrees north latitude is roughly Washington, DC?