explain xkcd - User contributions [en]

3253: Sunbeam

2026-06-02T10:52:47Z

82.132.239.195: /* Explanation */ Hedge the bets regarding *solar* hemisphere, and as best answer the questions asked about the comic location as I reasonably can. (Noting 'complaints' about over-verbosity, recently. But someone wants to know, so what else can I do?)

{{comic
| number = 3253
| date = June 1, 2026
| title = Sunbeam
| image = sunbeam_2x.png
| imagesize = 398x347px
| noexpand = true
| titletext = While weather control is typically thought of as a superpower, the unconscious ability of astronomers and astrophotographers to summon clouds is more properly classified as a curse.
}}

==Explanation==
{{incomplete|This page was created BY A TABLE SOON TO BE LIT BY THE SUN. Don't remove this notice too soon.}}

{{w|Astrophotography}} is the act of taking pictures of very distant objects. Common subjects of astrophotography include celestial bodies like planets and moons of the solar system, faraway galaxies, nebulae, spacecraft, or even {{w|Hubble Deep Field|empty patches of the sky}}.

In order to take such photos, one needs to know where these objects are in the sky. One major problem faced by Earth-based astrophotographers (most of them) is the fact that the Earth rotates. As the Earth rotates, it creates the illusion that the celestial objects being photographed are rotating through the night sky. Therefore, in order to get clear pictures of their subjects, astrophotographers must develop a strong understanding of how objects like a galaxy or the sun move through the sky, so that their cameras can compensate for this rotation and produce clear pictures.

This understanding of how objects move through the sky due to the Earth's rotation is the minor superpower referred to in the comic. As the sun is an example of an object in the sky, the intuition of astrophotographers allows them to predict where the sun will be in the future, and by extension, where the light flooding in through the window will be in the future. With this knowledge, Cueball, who assumingly has this minor superpower, can advise his friends to sit at the far table to avoid the light from the window hitting them. Though normally extra light may be considered desirable, such direct sunlight in this case would probably be considered problematic as there may be excessive heat and/or light. By contrast, the table currently beyond the beams of sunlight would be a perfectly acceptable place to sit and would remain so.

This ability is called a minor superpower because it's honestly not impactful. Regular people can often easily determine where the sun will fall through a window, making the claim of that being a 'superpower' questionable at best. And it's often useless, e.g., preventing people from being in a bad spot for their meal ostensibly because of sunlight usually has little bearing on how much they enjoy the meal. On the other hand, many people need to work in the shade for a plethora of good reasons, and some people occasionally need to work in sunlight. People who need to modulate the sunlight falling into their space, e.g. through large windows, often learn what times to adjust their blinds in a couple or three days at most.

This comic takes place north of the Sun's current ground-track (i.e. the line through the tropics which experience the Sun being directly overhead on any given day of the year, which changes over the course of the year due to the axial tilt of the Earth). In both hemispheres, the Sun can be found rising in the east in the morning, at its highest at around midday (exactly at true local midday, but must be adjusted for timezone issues such as the [[1799: Bad Map Projection: Time Zones|offset from the nominal local datum]] and [[:Category:Daylight saving time|DST]] effects), then setting in the west in the evening. (At least until you get close enough to the poles to experience no, or barely any, day or night according to the time of year.) Therefore, typically in the subtropical and temperate latitudes of the Northern Hemisphere, a shadow (and, by being framed by shadows, the light flooding in through windows) moves in a clockwise direction, from westerly, then north, then easterly. Similarly, shadows in the Southern Hemisphere move counter-clockwise, from a western direction, via south, eventually towards east. The light from the window in the comic is predicted to move from the center to the left, a clockwise rotation, consistent with the comic being set in the Northern Hemisphere, especially as this comic has been released almost in the middle of the time of the year where this scenario happens only to places north of the equator.

(The declinated angle of the Sun through the window is hard to measure, and without even knowing the time of day we cannot hope to further narrow down the true latitude of the l9cation and which direction the window faces. Although it is typical that, in temperate northern latitudes, major windows like the one shown are set to face as close to south as the orientation of buildings/rooms allow, to make the best use of daylight — particularly in the winter months. It is also a not unreasonable assumption that this meeting (or perhaps a meal) is occuring not long before/after noon, or even during it, with the Sun then approaching its zenith. Overall, it would be possible to see something very like this scene play out for [[Randall]] in his current home location, of around 42°N, at this time of year.)

The title text talks about another minor "superpower", that astrophotographers have, which makes clouds always seem to show up in front of the night sky. Because this "ability" is actually just coincidence,{{Citation needed}} that only appears causal to some, as well as that it interferes with their work, by ruining their photos, the title text more accurately classifies it as {{tvtropes|BlessedWithSuck|a curse}}, which is why the rest of the comic describes astrophotographers having only one "actual" superpower.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[Cueball, Megan, and White Hat are in a large dark room, presumably a restaurant, with two tables and a large window, with 4 panels and a topsection. The window is casting a large sunbeam between the two tables.]
:Cueball: Let's take the far table.
:Cueball: The closer one will be in the sun soon.
:[Caption below the panel:]
:Astrophotography gives you exactly one extremely minor superpower.
{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring White Hat]]
[[Category:Photography]]

Talk:3253: Sunbeam

2026-06-02T10:03:44Z

82.132.239.195:

did the transcript, but the explanation seems a bit daunting [[User:GreyFox|GreyFox]] ([[User talk:GreyFox|talk]]) 15:32, 1 June 2026 (UTC)
: You beat me to the punch! Very fast editing. And I agree, the explanation seems a little too out of reach for my knowledge base. Most likely explanation is that Astrophotography requires the knowledge of how the sun moves in relative to the Earth to take good photos, but that's just my guess. [[Special:Contributions/66.154.219.128|66.154.219.128]] 15:35, 1 June 2026 (UTC)
:: yeah, i tried to be fast; thanks for fixing the caption for me btw. searching astrophotography on wikipedia didnt really help much; lets wait for another more <s>nerdy</s> experienced user to get that done [[User:GreyFox|GreyFox]] ([[User talk:GreyFox|talk]]) 15:48, 1 June 2026 (UTC)
::: No problem. [[Special:Contributions/66.154.219.128|66.154.219.128]] 16:11, 1 June 2026 (UTC)

Can we deduce that the comic takes place in the northern hemisphere? {{unsigned|184.174.152.128|15:35, 1 June 2026}}
: That was my surface-level interpretation too, that this must be a Southern-facing window in the Northern hemisphere, since the East-West axis (the line that the light will travel along) is roughly parallel to the wall, and the light will pivot to the East (left) as the Sun moves West? [[User:SomeDee|SomeDee]] ([[User talk:SomeDee|talk]]) 15:52, 1 June 2026 (UTC)
:: Either that, or Cueball is wrong: on the southern hemisphere the sun still "moves" from east to west, but north of the observer. If this was the southern hemisphere, the sun beam would thus move towards the far table. [[Special:Contributions/2001:67C:2564:AB0C:1C57:EB42:6C3F:FD47|2001:67C:2564:AB0C:1C57:EB42:6C3F:FD47]] 16:02, 1 June 2026 (UTC)
::Could someone create a function which shows at which latitudes this scene could happen at which time of the day on which dates based on what we estimate the solar elevation angle shown to be. (Also assuming that Cueball is right)? Please? [[Special:Contributions/195.65.24.115|195.65.24.115]] 06:18, 2 June 2026 (UTC)

:: Barring reflections or other less-common situations, the window must indeed be in the northern hemisphere for Cueball to be correct. The window need not face directly south (unless the scene takes place precisely at the north pole). If it's at a sufficiently-high north latitude (e.g. that of the Boston area) the wall could face west or east and the nearer table could still get some sun a bit later. [[Special:Contributions/75.164.137.175|75.164.137.175]] 00:59, 2 June 2026 (UTC)

Yes, when I was in the southern hemisphere all my sense of where the Sun and stars should be moving to was totally off.
: Same, when I went to the Northern Hemisphere I was caught out when all the shadows started moving in the wrong direction [[User:MrCandela2|MrCandela2]] ([[User talk:MrCandela2|talk]]) 01:01, 2 June 2026 (UTC)

The sun could be reflecting off a nearby building, which would mess things up a bit. [[Special:Contributions/64.201.132.210|64.201.132.210]] 16:17, 1 June 2026 (UTC)
:Judging by the style of window, this is most likely near an older part of town or a more suburban area, where there are very few skyscrapers with reflective windows and a lot of wood and brick and mortar buildings, so I think that this is unlikely. [[Special:Contributions/66.154.219.128|66.154.219.128]] 16:31, 1 June 2026 (UTC)
::I was getting that old-downtown-church-vibe, which could easily be near a glass-plated skyscraper. [[Special:Contributions/64.201.132.210|64.201.132.210]] 20:23, 1 June 2026 (UTC)

Hang on, Randall got this wrong. Astrophotography (as defined by the Wikipedia page, the link is https://en.wikipedia.org/wiki/Astrophotography) is the act of taking pictures of the night sky... where there is no sun. An error on his part? [[Special:Contributions/66.154.219.128|66.154.219.128]] 16:21, 1 June 2026 (UTC)
: No, there's a transferrable skill between learning and predicting the movement of galaxies in the sky and predicting the movement of the sun in the sky. [[User:MrCandela2|MrCandela2]] ([[User talk:MrCandela2|talk]]) 01:01, 2 June 2026 (UTC)

Based on the title text, I'm guessing the joke is that because he said there will be sun, there will instead be clouds. His superpower is presumably summoning clouds. [[Special:Contributions/2607:FB91:17EC:E4FE:AD3:E858:6B10:E3E1|2607:FB91:17EC:E4FE:AD3:E858:6B10:E3E1]] 16:31, 1 June 2026 (UTC)

Wanted to say that you also learn how the sun moves as an astrophotographer, lots of planetary photography can happen during the day (Venus Mercury, strategic sun blocking) and need to take it into account, and there's also taking pictures of the sun with solar filters. So my interpretation of the joke was just genuinely pointing out the mini superpower of intuiting sun movement, rather than a joke about day versus night. [[Special:Contributions/142.114.245.145|142.114.245.145]] 16:36, 1 June 2026 (UTC)
: Hm, good point. Add that to the explanation if you can, I'm running out of the magic smoke that lets me edit pages. (motivation) [[Special:Contributions/66.154.219.128|66.154.219.128]] 16:38, 1 June 2026 (UTC)

I think the point is that someone who does astrophotography is intimately familiar with the motion of objects in the sky due to the rotation of the Earth, the sun is one such object that is visible during the day. Predicting its motion in the sky, due to the earth's rotation allows for the prediction of which table to sit at. The superpower is this predictive ability, which is normally not useful for all that much in modern life.

I don't think Randall messed this up. For example, the zodiac is defined as the Sun's path through the stars, even though the stars and the sun are not visible at the same time. Knowledge of how things move in the night sky is very related to how the Sun moves during the day.

To my mind, this comic is more closely related to the inherent calculations from within [[2463: Astrophotography]] (with the name of it being not a coincidence) than merely being good at photographing nebulae/etc. [[Special:Contributions/81.179.199.253|81.179.199.253]] 19:51, 1 June 2026 (UTC)

FWIW you don't need no Astrophotography to predict the sunny table. I see it on my dogs as they lay on the floor after lunch. --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 20:26, 1 June 2026 (UTC)
:Conclusion: your dogs know about astrophotography ;-) [[User:Martin|Martin]] ([[User talk:Martin|talk]]) 01:28, 2 June 2026 (UTC)

Is there something about the illustration that makes it clear which direction the sun is going to move? Or does the speaker in the comic require additional external knowledge about which direction the window is facing? -- [[Special:Contributions/108.18.36.182|108.18.36.182]] 22:21, 1 June 2026 (UTC)

:They only need to know that the sun travels east to west in the sky, and the approximate orientation of the window. (Without regard to the hemisphere or season; in re [https://www.explainxkcd.com/wiki/index.php?title=3253:_Sunbeam&diff=414125&oldid=414124].) [[Special:Contributions/2601:642:4C00:7984:B516:F866:A46E:3715|2601:642:4C00:7984:B516:F866:A46E:3715]] 00:10, 2 June 2026 (UTC)

If I'm not mistaken, the direction of the sun relative to the movement is not perfectly predicted by the hemisphere, but by the one of the two following possibilities: 1. the scene is north of the tropic of cancer, or 2. the person is north of the tropic of capricorn and south of the tropic of cancer at the time of year when the sun passes to their south. Note that if you stand just south of the equator during the northern hemisphere winter, the sun passes to the south, and thus, the scene would work in the southern hemispere. Equally,if you stand just north of the equator during the northern hemisphere summer, the sun will pass to the north, and the scene does not work. {{unsigned|Billdxdydz|05:46, 2 June 2026}}