explain xkcd - User contributions [en]

Talk:3182: Telescope Types

2025-12-18T23:58:44Z

Deebster: fix link

no vampire jokes 🥀 ([[1791]]) [[User:TheTrainsKid|TheTrainsKid]] ([[User talk:TheTrainsKid|talk]]) 00:08, 18 December 2025 (UTC)

Got down some preliminary descriptions of each telescope type used [[Special:Contributions/185.132.133.218|185.132.133.218]] 01:44, 18 December 2025 (UTC)

insert that one mickey mouse meme with the caption "what a fucking narcissist"
[[User:Yaokuan ITB|Yaokuan ITB]] ([[User talk:Yaokuan ITB|talk]]) 02:33, 18 December 2025 (UTC)

abnormally low joke-to-real ratio for this format of comic! [[Special:Contributions/2601:241:8002:3E0:C0A2:9DA:ED39:D13F|2601:241:8002:3E0:C0A2:9DA:ED39:D13F]] 03:21, 18 December 2025 (UTC)
:I noticed that... I think this might've originally been 'look at all these cool telescope types', but then he realized he had to put some sort of joke somewhere. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 03:27, 18 December 2025 (UTC)

Can someone make a category for The Core (2003)? It's been mentioned often enough. [[Special:Contributions/83.245.251.49|83.245.251.49]] 09:22, 18 December 2025 (UTC)
:Can you list 4 more comics then I will make the category. I think that is about the limit for when to make a new category. I know there are a few more but is it only 2-3more? --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:00, 18 December 2025 (UTC)
::All I can think of is [[673: The Sun]]. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 15:09, 18 December 2025 (UTC)
:::Also mentioned in the title text of [[2858: Thanksgiving Arguments]]. --[[Special:Contributions/208.59.176.206|208.59.176.206]] 15:24, 18 December 2025 (UTC)
:: The [[:Category: The Core|The Core]] category was already created, nearly two years ago. This comic is the 7th reference --[[User:Deebster|Deebster]] ([[User talk:Deebster|talk]]) 23:54, 18 December 2025 (UTC)

> This would not […] end well for the drinker.

Would it though? ''Drinking'' elemental mercury, while not great on nutritional value, should be mostly safe (and I'm using that word quite loosely). The most danger would be while drinking and expelling it, when there's a danger of inhaling mercury vapors, right? --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 10:29, 18 December 2025 (UTC)

... Agreed. Elemental mercury is dangerous when inhaled, not when drinked. https://en.wikipedia.org/wiki/Mercury_poisoning [[Special:Contributions/109.81.171.81|109.81.171.81]] 21:12, 18 December 2025 (UTC)

It wouldn't take much work to make the "Real?" column all contain only "yes" [[Special:Contributions/136.32.133.124|136.32.133.124]] 12:05, 18 December 2025 (UTC)

As all others are refractors or reflectors, can cardboard tube be considered a diffractor? As it is the only thing that it does.--[[User:Trimutius|Trimutius]] ([[User talk:Trimutius|talk]]) 15:43, 18 December 2025 (UTC)

> Children may sometimes use tubes [...]

It's not just children. I've seen "viewing tubes" in at least a couple of places, hard-mounted metal tubes that point at particular points of interest. I'm not finding any good references, but here's a photo showing some at the top of a nearby mountain: https://maps.app.goo.gl/wwnYJ1zEQEXzjyJS8 [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 18:07, 18 December 2025 (UTC)

Talk:3182: Telescope Types

2025-12-18T23:54:07Z

Deebster: comment on The Core category

no vampire jokes 🥀 ([[1791]]) [[User:TheTrainsKid|TheTrainsKid]] ([[User talk:TheTrainsKid|talk]]) 00:08, 18 December 2025 (UTC)

Got down some preliminary descriptions of each telescope type used [[Special:Contributions/185.132.133.218|185.132.133.218]] 01:44, 18 December 2025 (UTC)

insert that one mickey mouse meme with the caption "what a fucking narcissist"
[[User:Yaokuan ITB|Yaokuan ITB]] ([[User talk:Yaokuan ITB|talk]]) 02:33, 18 December 2025 (UTC)

abnormally low joke-to-real ratio for this format of comic! [[Special:Contributions/2601:241:8002:3E0:C0A2:9DA:ED39:D13F|2601:241:8002:3E0:C0A2:9DA:ED39:D13F]] 03:21, 18 December 2025 (UTC)
:I noticed that... I think this might've originally been 'look at all these cool telescope types', but then he realized he had to put some sort of joke somewhere. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 03:27, 18 December 2025 (UTC)

Can someone make a category for The Core (2003)? It's been mentioned often enough. [[Special:Contributions/83.245.251.49|83.245.251.49]] 09:22, 18 December 2025 (UTC)
:Can you list 4 more comics then I will make the category. I think that is about the limit for when to make a new category. I know there are a few more but is it only 2-3more? --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:00, 18 December 2025 (UTC)
::All I can think of is [[673: The Sun]]. --'''''[[User:DollarStoreBa'al|DollarStoreBa'al]][[User Talk:DollarStoreBa'al|Converse]] 15:09, 18 December 2025 (UTC)
:::Also mentioned in the title text of [[2858: Thanksgiving Arguments]]. --[[Special:Contributions/208.59.176.206|208.59.176.206]] 15:24, 18 December 2025 (UTC)
:: [The Core] category was already created, nearly two years ago. This comic is the 7th reference --[[User:Deebster|Deebster]] ([[User talk:Deebster|talk]]) 23:54, 18 December 2025 (UTC)

> This would not […] end well for the drinker.

Would it though? ''Drinking'' elemental mercury, while not great on nutritional value, should be mostly safe (and I'm using that word quite loosely). The most danger would be while drinking and expelling it, when there's a danger of inhaling mercury vapors, right? --[[User:Coconut Galaxy|Coconut Galaxy]] ([[User talk:Coconut Galaxy|talk]]) 10:29, 18 December 2025 (UTC)

... Agreed. Elemental mercury is dangerous when inhaled, not when drinked. https://en.wikipedia.org/wiki/Mercury_poisoning [[Special:Contributions/109.81.171.81|109.81.171.81]] 21:12, 18 December 2025 (UTC)

It wouldn't take much work to make the "Real?" column all contain only "yes" [[Special:Contributions/136.32.133.124|136.32.133.124]] 12:05, 18 December 2025 (UTC)

As all others are refractors or reflectors, can cardboard tube be considered a diffractor? As it is the only thing that it does.--[[User:Trimutius|Trimutius]] ([[User talk:Trimutius|talk]]) 15:43, 18 December 2025 (UTC)

> Children may sometimes use tubes [...]

It's not just children. I've seen "viewing tubes" in at least a couple of places, hard-mounted metal tubes that point at particular points of interest. I'm not finding any good references, but here's a photo showing some at the top of a nearby mountain: https://maps.app.goo.gl/wwnYJ1zEQEXzjyJS8 [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 18:07, 18 December 2025 (UTC)

3108: Laser Danger

2025-06-29T10:45:50Z

Deebster: /* Transcript */ Finalise transcript

{{comic
| number = 3108
| date = June 27, 2025
| title = Laser Danger
| image = laser_danger_2x.png
| imagesize = 684x272px
| noexpand = true
| titletext = To combat the threat, many airlines are installing wing-mounted spray bottles.
}}

==Explanation==
{{incomplete|This page was created TO DISTRACT A GIANT KITTEN. Don't remove this notice too soon.}}
Shining a laser at a plane is a federal crime in the United States, and similarly proscribed in many other locations. A sufficiently powerful laser can disorient, distract and/or blind the pilot operating the aircraft. This can prove particularly dangerous to the safety of the aircraft and its occupants during takeoff and landing, when planes are likely to have altitudes and orientations particularly susceptible to laser interference, and are phases that are already hazardous periods of flight. This 'use' of lasers was previously discussed in [[3030: Lasering Incidents]].

Megan humorously claims that there's another reason why lasering a plane is illegal: to avoid provoking cats into leaping at them. Cats are known to [[729: Laser Pointer|chase and jump onto]] the dots created by laser pointers. Cats also prey on birds, with estimates of 1.3 to 3.7 billion birds killed each year. Of course, a cat would be unable to jump to the height of a flying plane{{Citation needed}}. If the cat were able to reach the plane, it would find itself hilariously outsized, though colliding with the plane midair could cause damage akin to a bird strike (e.g. shattered windshield or engine failure).

The title text alludes to the fact that cats do not like getting wet, and one of the methods people use to discourage cats from a place (or activity) that is unwanted is to use spray bottles to wet their fur. The spray bottle might also emit a hissing sound, which cats associate with other cats threatening them. The "wing mounted spray bottles" on aircraft could be a reference to fuel dump tubes, which spray out fuel to lighten the aircraft, commonly used before emergency landings (especially soon after take-off, when a nearly full load of fuel is now more trouble than it should have been). To combat against actual physical threats to aircraft in real life, El Al (The Israeli national airline) and government aircraft {{w|Air Force One|used by heads of state}} often have various {{w|Flare (countermeasure)|countermeasures}} installed.

==Transcript==
: Megan: Shining laser pointers at planes is a federal crime. It's incredibly dangerous.
: Cueball: Oh, because it can blind the pilot?
: Megan: That's one reason...

: [A plane is shown, with a green laser pointer aimed at it.]

: [The laser disappears. A cat, approximately the same size as the plane, pounces on the plane and sends it tumbling.]

{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Aviation]]
[[Category:Cats]]
[[Category:Comics with color]]

3093: Drafting

2025-05-24T01:46:00Z

Deebster: revert vandalism

{{comic
| number = 3093
| date = May 23, 2025
| title = Drafting
| image = drafting_2x.png
| imagesize = 317x518px
| noexpand = true
| titletext = A 5% efficiency gain at the cost of a 99% efficiency loss
}}

==Explanation==
{{incomplete|This page was created by a bot that should not have tried this. The explanation is still a DRAFT. Don't remove this notice too soon.}}
This is another one of [[Randall|Randall's]] [[:Category: Tips|Tips]], this time an Aerospace tip.

{{w|Drafting (aerodynamics)|Drafting}} is an aerodynamic technique where one moving object follows another one closely to reduce drag by using the first objects {{w|slipstream}}. It is used in various sports, most prominently {{w|cycling}}.

The comic explores the idea of using drafting for rockets and states that while it theoretically works, it isn't really recommended.

The title text gives more details on this, claiming that there is an efficiency gain of 5% through drafting via the general mechanism, it also comes with a 99% loss, likely because a drafting rocket would almost certainly be annihilated by the leading rocket.

Generally, this could be understood because land transportation is based on traction (pulling yourself along a surface via friction). At higher speeds (above 60km/h), the dominant force becomes wind drag. {{w|Energy-efficient driving}} at these higher speeds can be improved by drafting behind another vehicle. This doesn't apply to rockets because they do not move themselves via friction but rather via Newton's third law (throwing stuff backwards). This means that the front rocket would just push the back rocket against its own thrust (among other bad effects).

==Transcript==
:[A rocket with two boosters is launching going towards the top right corner. It has a two-stage core and two boosters, and they produce three flames from their exhaust and beneath these flames is a large exhaust plume fanning out behind the rocket most of the way towards the bottom of the panel. A smaller rocket is following the first rocket. It is very close to the first rocket, so most of the smaller rocket is inside the exhaust plume from the larger rocket. The smaller rocket does not have boosters, but still produces three smaller flames from its exhaust. Beneath these flames the smaller rocket also leaves a large but slimmer exhaust plume that exits the panel at the bottom left corner.]

:[Caption below the panel:]
:Aerospace tip: Although the technique reduces atmospheric drag for many types of vehicles, you should '''''never''''' try to improve rocket launch efficiency through drafting.

{{comic discussion}}<noinclude>

[[Category:Tips]]
[[Category:Rockets]]