# ­xkcd thread **URL:** \ **Category:** Cafe Society\ **Tags:** comic-strips\ **Created:** [May 28, 2020, 12:57am UTC](https://boards.straightdope.com/t/xkcd-thread/854574 "2020-05-28T00:57:03Z")\ **Posts on this page:** 20\ **Page:** 261
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [November 26, 2025, 8:37pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5203 "2025-11-26T20:37:12Z")
> **[Satellite Imagery](https://xkcd.com/3173/)** [![](https://imgs.xkcd.com/comics/satellite_imagery.png) ](https://imgs.xkcd.com/comics/satellite_imagery.png) “Every weekend I take an ATV out into the desert and spend a day tracing a faint “(C) GOOGLE 2009” watermark across the landscape.” ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 26, 2025, 8:41pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5204 "2025-11-26T20:41:03Z")
Be better if it was (C) GOOGLE 1995. _Really_ f\*\*\* with their heads! ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [November 29, 2025, 1:19am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5205 "2025-11-29T01:19:20Z")
> **[Bridge Clearance](https://xkcd.com/3174/)** [![](https://imgs.xkcd.com/comics/bridge_clearance.png) ](https://imgs.xkcd.com/comics/bridge_clearance.png) “A lot of the highway department’s budget goes to adjusting the sign whenever the moon passes directly overhead.” ---
**Author:** ![Ponderoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponderoid/32/19221_2.png) [@Ponderoid](https://boards.straightdope.com/u/Ponderoid)\ **Post date:** [November 29, 2025, 2:40am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5206 "2025-11-29T02:40:56Z")
> [@dtilque](#): > > whenever the moon passes directly overhead. So, this spot is no further than 28.5 degrees from the equator. And given the sign is in English with 'murrican units, that pretty much limits the location to somewhere in deep south Texas or Florida, I think. Oh, and Hawaii. Any American bases in that range? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 29, 2025, 3:56am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5207 "2025-11-29T03:56:17Z")
Huh? Locations less poleward than ~23 degrees have an 1AU ~= 8 lightminute obstruction a couple times per day. ---
**Author:** ![Ponderoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponderoid/32/19221_2.png) [@Ponderoid](https://boards.straightdope.com/u/Ponderoid)\ **Post date:** [November 29, 2025, 4:48am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5208 "2025-11-29T04:48:52Z")
Did you mean a couple times per year? Of course, there are lots of stars a lot closer than 46 billion light years that pass over every location on Earth once a day. And this reminds me of this older xkcd: [![](https://imgs.xkcd.com/comics/angular_size.png) ](https://imgs.xkcd.com/comics/angular_size.png) ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [November 29, 2025, 5:32am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5209 "2025-11-29T05:32:42Z")
> [@Ponderoid](#): > > Of course, there are lots of stars a lot closer than 46 billion light years that pass over every location on Earth once a day. Nope. They each pass over a very narrow strip of latitude once a day. ETA: On rereading, I realize you meant they will collectively pass over every location. Yeah pretty much, especially if you count the stars in other galaxies. There are some TNOs that have extreme inclinations, including a number that are in retrograde orbits. Some have orbits pretty close to perpendicular to the plane of the Solar System. Those will eventually pass over almost everywhere on Earth. Examples 2015 KZ120 has inclination of 84.49 degrees; 2016 FH13 has 93.57. There’s some others with similar inclinations. Source: [List of known trans-Neptunian objects](https://www.johnstonsarchive.net/astro/tnoslist.html) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 29, 2025, 2:01pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5210 "2025-11-29T14:01:58Z")
> [@Ponderoid](#): > > Of course, there are lots of stars a lot closer than 46 billion light years that pass over every location on Earth once a day. Not really. Note from your chart that even a star with a really large angular size only passes directly over an area about the size of a computer keyboard, and most stars are far, far smaller than that in the sky. Most places you could put a sign, no star would ever pass directly over them (though you’d have a lot of misses of less than a degree, but at stellar distances, that’s a big miss). ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [November 29, 2025, 2:16pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5211 "2025-11-29T14:16:45Z")
Mind. Blown. (I knew about the moon and sun, from eclipse maps…but the rest amazes me. Though I shouldn’t have been too surprised about Venus, having taught myself about its transit across the sun…) ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [November 29, 2025, 3:29pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5212 "2025-11-29T15:29:23Z")
Which reminds me of Olber’s paradox… ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 29, 2025, 3:35pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5213 "2025-11-29T15:35:08Z")
Isaac Asimov wrote an essay “Heaven On Earth”, where he translated angular diameter to sizes on Earth’s surface; or as he put it, if the Earth was transparent and you viewed the sky from the Earth’s center. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 29, 2025, 3:37pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5214 "2025-11-29T15:37:31Z")
Shouldn’t Venus and Mars be VERY variable in size depending on their opposition/ conjunction distances? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 29, 2025, 3:44pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5215 "2025-11-29T15:44:33Z")
Yep. The max vs min distance ratio for both planets is very roughly 6.5 to 1. Which would lead to the same amount of variability of the shading diameter projected onto the Earth. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 29, 2025, 3:45pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5216 "2025-11-29T15:45:48Z")
> [@Ponderoid](#): > > Did you mean a couple times per year? I have no idea what I meant. It was late, I was stupid. But yeah, “year” makes a lot more sense there. 🤦‍♂️ ---
**Author:** ![N9IWP](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/n9iwp/32/3154_2.png) [@N9IWP](https://boards.straightdope.com/u/N9IWP)\ **Post date:** [November 29, 2025, 3:59pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5217 "2025-11-29T15:59:45Z")
What about starlink and other satellites? Depending on you location they could be overhead. Some briefly, and some geosynchronous ones all the time for certain locales. Brian ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [November 29, 2025, 5:11pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5218 "2025-11-29T17:11:19Z")
All hogwash. The sky, sun, stars… are just projections shown to us flateathers. You sciency types just won’t acknowledge it. Even Munroe has been bought off by **BIG DOME**. ---
**Author:** ![Zakalwe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zakalwe/32/270_2.png) [@Zakalwe](https://boards.straightdope.com/u/Zakalwe)\ **Post date:** [November 29, 2025, 5:24pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5219 "2025-11-29T17:24:10Z")
> [@smithsb](#): > > Even Munroe has been bought off by You’re not supposed to talk about that. If you get disappeared, don’t say I didn’t warn you. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [November 29, 2025, 5:42pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5220 "2025-11-29T17:42:22Z")
> [@Chronos](#): > > Not really. Note from your chart that even a star with a really large angular size only passes directly over an area about the size of a computer keyboard, and most stars are far, far smaller than that in the sky. Most places you could put a sign, no star would ever pass directly over them (though you’d have a lot of misses of less than a degree, but at stellar distances, that’s a big miss). But there’s lots more stars than what even the best telescopes can see. Gaia has mapped something like 2 billion stars and that’s only about 1% of the stars in our galaxy. Well, OK the stars in our galaxy are concentrated in a relatively narrow band. There won’t be nearly as many in the rest of the sky. But there’s zillions of other galaxies out there and they aren’t concentrated. Consider the Hubble Deep Field and other deep field. Those show that even in areas of the sky that are seemingly bare, there’s lots of very distant galaies filling in those gaps. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [November 29, 2025, 6:01pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5221 "2025-11-29T18:01:29Z")
There needs to be a sign warning of low-flying aircraft under 40,000 feet. Maybe a lot lower! ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 29, 2025, 6:03pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5222 "2025-11-29T18:03:46Z")
At what point would the angular size correspond to a footprint smaller than the Planck length? ETA: my rough guesstimate based on the Planck length and the radius of the Earth is that something would have to be 1042 times as far away as it is wide to appear that small. Since there are fewer than 1016 meters in a light year, that would have to mean “very small and very far away”. [Previous page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=260) [Next page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=262)