explain xkcd - User contributions [en]

3096: Check Engine

2025-06-01T10:35:31Z

162.158.158.169: Why would 'they' be a un-introduced group when the astronomers are previously mentioned, thus making far more sense in context?

{{comic
| number = 3096
| date = May 30, 2025
| title = Check Engine
| image = check_engine_2x.png
| imagesize = 331x383px
| noexpand = true
| titletext = They say it's probably safe to keep orbiting for a while, but if it stays on or starts flashing we might have to call someone.
}}

==Explanation==
{{incomplete|This page was created by THE SOLAR PIT CREW. Don't remove this notice too soon.}}
{{w|Sunspot|Sunspots}} are temporary, relatively small, darker (because cooler) regions on the surface of Earth's Sun. The number of sunspots that can be observed varies over an approximately 11-year cycle. The current cycle is {{w|Solar_cycle_25|the 25th since reckoning began in 1755}}. Solar Cycle 25, which began in December 2019 and is expected to peak around mid-2025, has been more active than anticipated, raising some concerns about the impacts of recent solar flares and associated space weather events.

The joke in this comic is that the sunspot array shown has taken the form of a "{{w|Check engine light}}", found on the instrument panel of most automobiles. The illumination of this light means that the automobile's onboard computer has detected an engine malfunction, which should be checked out by an experienced mechanic. For such a signal to appear among the nuclear fires and plasma of the sun would most certainly be of concern to astronomers.

Many drivers will barely notice a Check Engine light, and may hope that they ''never'' have cause to see it appear except maybe briefly during the turning of the ignition key as one of the bulb-checks. If it lights persistently before or during driving, it could mean a costly problem. Or at least the inconvenience of paying someone to investigate the problem, and then to solve some broken sensor issue. For the sake of practicality, not all warning lights are so self-explanatory as the version shown in the comic, and as a vehicle gets gets older, with various faults becoming more likely to occur, it's not uncommon for an owner to have to refer to the manual to discover what a newly persistent glyph on their dashboard actually entails, or at least what they can do about it.

As we don't appear to be cycling the Sun's ignition process (i.e., it hasn't recently stalled, which would be a worry in itself) the showing of the light/dark-patch would probably be very concerning, and hopefully someone at least has the owner's manual in order to run through any initial troubleshooting, before perhaps a more extensive check is made at the local solar-repair shop to clear the error. Given the rotating nature of the star, and Earth's orbit, one might also wonder how long this, or any other additional warnings, might be shown before it becomes visible to {{w|Solar viewer|suitably equipped}} viewers of the Sun.

The title text says that "they" (presumably the astronomers) advise that it's probably safe for Earth to continue to orbit the Sun unless and until there is a change in the nature of the "check engine light" sunspot array. Such a change, on an instrument panel, signals that the matter needs immediate attention, lest something dramatic and expensive occur, such as an [https://www.reddit.com/r/explainlikeimfive/comments/l8j0ip/eli5_what_is_a_seized_engine/ engine seizure], which can be spectacular and is irreparable. The solar equivalent of an engine seizure would be a {{w|Nova|nova}}, which would definitely be of concern to astronomers (and everyone else), and for which the prospect of "calling [[673: The Sun | someone]]" that can do anything useful (a cosmic tow truck to pull Earth to a safe distance?) seems remote.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[A pattern in the form of a "check engine" light (as displayed on a car's instrument panel) is shown on the surface of the Sun, in the bottom right quarter. The pattern has a pictogram of a motor on the top and the text "Check Engine" below it, both in orange inside a black square, matching the orange color of the Sun.]

:[Caption below the panel:]
:This new sunspot cluster has raised concern among astronomers

{{comic discussion}}<noinclude>
[[Category:Comics with color]]
[[Category:Astronomy]]

Talk:3041: Unit Circle

2025-01-23T14:24:04Z

162.158.158.169:

First [[Special:Contributions/162.158.175.72|162.158.175.72]] 23:00, 22 January 2025 (UTC)

This would actually be so helpful for my geometry class right now '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 23:06, 22 January 2025 (UTC)
:Are you saying you have problem with abstract thinking? Why should matter if the unit circle had radius 1 yard, 1 foot, 1 meter or 1 lightsecond? -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:12, 22 January 2025 (UTC)
::I don’t like having things defined as “x” and like to have exact measurements. The diagram just looks cleaner to me that way '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 23:38, 22 January 2025 (UTC)
:::There's nothing stopping you from considering non-dimensional lengths to be whatever unit you want. If you just write in, for example, "cm" after any linear dimensions, and corresponding units for areas and volumes, that's fine.[[Special:Contributions/162.158.158.169|162.158.158.169]] 14:24, 23 January 2025 (UTC)
::I prefer units of light-nanoseconds or the metric version parnsecs (don't think about it too hard :P) {{unsigned|SammyChips}} SammyChips 23:58, 22 January 2025 (UTC)
:::I like [[3038|square acrminutes per steradian]] '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 02:38, 23 January 2025 (UTC)
:::Please sign off with <code><nowiki>~~~~</nowiki></code>, or change your signature to include a link to either your talk page or user page. Thank you! '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 01:25, 23 January 2025 (UTC)
:::SammyChips, if that is supposed to be Parallax nano-seconds, you should understand that that is probably more like a Giga-Parsec. The parsec is the distance at which an object appears to move one second of arc when the Earth moves halfway around its orbit. (though I'm not sure which orientation.) [[User:Divad27182|Divad27182]] ([[User talk:Divad27182|talk]]) 03:34, 23 January 2025 (UTC)
:::My Millennium Falcon gets 14 parsecs to the Kessel Run, and that’s the way I likes it! [[Special:Contributions/172.68.186.34|172.68.186.34]] 06:26, 23 January 2025 (UTC)
:::I'm going to take all these desires for weird units with a barn-megaparsec of nackle. [[Special:Contributions/172.69.195.160|172.69.195.160]] 07:00, 23 January 2025 (UTC)
:yo Tori, [https://www.youtube.com/watch?v=VEJWE6cpqw0 ''this''] might help you with geometry too ;) [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 11:14, 23 January 2025 (UTC)

Are "they" also searching for {{w|Doubling the cube|Apollo's doubled altar}}? [[User:Divad27182|Divad27182]] ([[User talk:Divad27182|talk]]) 03:22, 23 January 2025 (UTC)

I guess the correct wording is that $\pi$ is a trancendent number. Some irrational numbers e.g. $\sqrt{2}$ can be constructed by compass and ruler. {{unsigned ip|172.68.185.165|07:12, 23 January 2025}}
:To be more precise, constructable irrational numbers are those that can be obtained through taking square roots, even repeatedly. Transcendental numbers are out, but so are things like cube roots. Note also that the fact that there are no "absolute units" of length is a quirk of Euclidean geometry -- in, say, hyperbolic world, a unit circle like this could actually work. [[Special:Contributions/172.68.213.153|172.68.213.153]] 09:10, 23 January 2025 (UTC)

Talk:3041: Unit Circle

2025-01-23T14:23:30Z

162.158.158.169:

First [[Special:Contributions/162.158.175.72|162.158.175.72]] 23:00, 22 January 2025 (UTC)

This would actually be so helpful for my geometry class right now '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 23:06, 22 January 2025 (UTC)
:Are you saying you have problem with abstract thinking? Why should matter if the unit circle had radius 1 yard, 1 foot, 1 meter or 1 lightsecond? -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:12, 22 January 2025 (UTC)
::I don’t like having things defined as “x” and like to have exact measurements. The diagram just looks cleaner to me that way '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 23:38, 22 January 2025 (UTC)
:::There's nothing stopping you from considering non-dimensional lengths to be whatever unit you want. If you just write in, for example, "cm" after any linear dimensions, and corresponding units for areas and volumes, that's fine.
::I prefer units of light-nanoseconds or the metric version parnsecs (don't think about it too hard :P) {{unsigned|SammyChips}} SammyChips 23:58, 22 January 2025 (UTC)
:::I like [[3038|square acrminutes per steradian]] '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 02:38, 23 January 2025 (UTC)
:::Please sign off with <code><nowiki>~~~~</nowiki></code>, or change your signature to include a link to either your talk page or user page. Thank you! '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 01:25, 23 January 2025 (UTC)
:::SammyChips, if that is supposed to be Parallax nano-seconds, you should understand that that is probably more like a Giga-Parsec. The parsec is the distance at which an object appears to move one second of arc when the Earth moves halfway around its orbit. (though I'm not sure which orientation.) [[User:Divad27182|Divad27182]] ([[User talk:Divad27182|talk]]) 03:34, 23 January 2025 (UTC)
:::My Millennium Falcon gets 14 parsecs to the Kessel Run, and that’s the way I likes it! [[Special:Contributions/172.68.186.34|172.68.186.34]] 06:26, 23 January 2025 (UTC)
:::I'm going to take all these desires for weird units with a barn-megaparsec of nackle. [[Special:Contributions/172.69.195.160|172.69.195.160]] 07:00, 23 January 2025 (UTC)
:yo Tori, [https://www.youtube.com/watch?v=VEJWE6cpqw0 ''this''] might help you with geometry too ;) [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 11:14, 23 January 2025 (UTC)

Are "they" also searching for {{w|Doubling the cube|Apollo's doubled altar}}? [[User:Divad27182|Divad27182]] ([[User talk:Divad27182|talk]]) 03:22, 23 January 2025 (UTC)

I guess the correct wording is that $\pi$ is a trancendent number. Some irrational numbers e.g. $\sqrt{2}$ can be constructed by compass and ruler. {{unsigned ip|172.68.185.165|07:12, 23 January 2025}}
:To be more precise, constructable irrational numbers are those that can be obtained through taking square roots, even repeatedly. Transcendental numbers are out, but so are things like cube roots. Note also that the fact that there are no "absolute units" of length is a quirk of Euclidean geometry -- in, say, hyperbolic world, a unit circle like this could actually work. [[Special:Contributions/172.68.213.153|172.68.213.153]] 09:10, 23 January 2025 (UTC)