3207: Bad Map Projection: Zero Declination

2026-02-17T16:36:56Z

2A00:23C8:F529:1301:C8AE:DBC6:E488:D2C4: /* Explanation */ wrong word

{{comic
| number = 3207
| date = February 13, 2026
| title = Bad Map Projection: Zero Declination
| image = bad_map_projection_zero_declination.png
| imagesize = 740x544px
| noexpand = true
| titletext = 'The zero line in WMM2025 passes through a lot of population centers; I wonder what year the largest share of the population lived in a zone of less than 5° of declination,' he thought, derailing all other tasks for the rest of the day.
}}

==Explanation==
{{incomplete|This page was created recently by a misaligned map. Don't remove this notice too soon.}}
This is the tenth comic in the [[:Category:Bad Map Projections|Bad Map Projections]] series, displaying Bad Map Projection #216: Zero Declination.

While the Earth's magnetic field is broadly aligned North-South, the actual alignment of the magnetic field varies over time and position. The difference between True North (the axis of Earth's rotation) and Magnetic North (the direction a compass will point) will vary depending on your position, and is known as the {{w|Magnetic Declination}} of that point.

The comic shows a map that has been distorted based on the Magnetic Declination so that Magnetic North for every point is pointed toward the top of the map. If this were reality, then Magnetic North would always be aligned with True North, or in other words, there would be Zero Declination at all points.

The red arrows indicate the distortions from the starting map required to make Magnetic North be at the top.

In the title text, "WMM2025" refers to the 2025 version of the {{w|World Magnetic Model}}, a representation of the Earth's magnetic field. You can see it [https://web.archive.org/web/20260212034745/https://www.ncei.noaa.gov/sites/default/files/inline-images/D.jpg here]. The "zero line" is in green, which shows where in the world magnetic declination is 0°. [[Randall]] has presumably wasted a day trying to figure out what year has had the most population living in an area of less than 5° declination by searching through previous WMM maps. He appears to have not found the answer, but luckily explainxkcd user Ahogue [[356|finished the job]] and made a [https://awhogue.github.io/zero-declination/output/ beautiful interactive map] to let you see that the answer is 2000!

You can see magnetic declination [https://www.ncei.noaa.gov/maps/historical-declination/ historical data here].

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}

{{comic discussion}}<noinclude>

[[Category:Comics with red annotations]]
[[Category:Bad Map Projections]]
[[Category:Comics with color]]

3208: SNEWS

2026-02-17T16:35:20Z

2A00:23C8:F529:1301:C8AE:DBC6:E488:D2C4: /* Explanation */ wrong word

{{comic
| number = 3208
| date = February 16, 2026
| title = SNEWS
| image = snews_2x.png
| imagesize = 740x321px
| noexpand = true
| titletext = People say setting of fireworks indoors is dangerous, but I looked at their energy release and it's like 10^-40 foe; totally negligible.
}}

==Explanation==
{{incomplete|This page was created by a Type Ia firework display that Ponytail set off. Don't remove this notice too soon.}}
[[Ponytail]] is showing [[Hairy]] her bedroom. Hairy asks about the large device on the ceiling, and Ponytail explains that it is part of the {{w|SNEWS}} (SuperNova Early Warning System). This detects {{w|neutrino|neutrinos}} (tiny particles that travel near the speed of light, rarely interacting with matter) to give pre-notice of supernovae, as neutrinos are produced in large quantities during the collapse of the star core, which occurs hours before the main photon production. She explains this gives astronomers warning, allowing them to observe the event with telescopes and other instruments.

Ponytail employs hyperbole, because even if they were all interested in supernovae, not every astronomer or observatory will be immediately situated to view a particular point in the sky. For example, they may need to wait for the Earth's rotation, causing the phenomenon to "rise" in the east. Others may be located at unfavorable latitudes where the object will never appear above the Earth's horizon. And, it may take some time before the supernova reaches an apparent magnitude that is visible during the daytime.

Hairy then asks regarding the nature of the visible equipment mounted on the ceiling, which has several protruding barrels. His first assumption is that it is either detector as part of the SNEWS, or some kind of telescope to be used in the event the SNEWS goes off. Ponytail explains that the device it is in fact a fireworks launcher, for the purposes of waking her up so she can witness the supernova herself. This is a '''very''' bad idea for a multitude of reasons. Reckless use of fireworks is already known for causing significant property damage and personal injury even when used outdoors; launching fireworks inside the house means causing an explosion in a confined area, guaranteeing that it will hit the building, maximizing the opportunity for the conflagration to ignite something flammable on the structure, and containing and therefore amplifying the sound of the burst (which can already deafen people who are too close).

Some people don't easily wake up to a simple alarm clock, especially if it is in reach and has a "snooze" function where a button will silence the alarm for several minutes before it beeps again. Note the similar sounds of "snooze" and SNEWS may be part of the joke.

Since historical supernovae have been visible from 6 months to nearly 2 years, it would be unlikely that Ponytail sleeps through a new one in its entirety, although there would still be significant cachet for any astronomer lucky enough to be able to legitmately say that they had seen the 'first light' at the earliest opportunity. It would also be difficult for her to ''not'' sleep through part of the supernova, for the same reason.

Understandably, Hairy {{tvtropes|ScrewThisImOuttaHere|leaves to sleep at his own house}}.

The comic title "SNEWS" is an acronym from the beginning of the strip: SuperNova Early Warning System. It is also a play on "news"

The title text is a play on the tremendous amount of energy released by a supernova. The {{w|Foe (unit)|foe}} is an unofficial unit of energy equal to 10^44 Joule (but named directly from initials in the original quantity of "ten to the fifty-one ergs", involving a {{w|Erg|pre-SI}} measurement of energy), which is approximately on the order of the usual amount of energy released by a supernova. In comparison, human-scale amounts of energy — even relatively significant ones such as firework detonations — are negligible. This ignores the fact that energy releases that are "negligible in comparison to a supernova" can still be easily fatal to humans; even the largest man-made nuclear explosion is approximately ''twenty-seven'' orders of magnitude less than the baseline 'foe' value. The described "10-40 foe" is equal to 10 kJ, the energy released by the complete combustion of about 0.6 g of table sugar (sucrose), or the decomposition of about 6 g of nitrocellulose.

==Transcript==
{{incomplete transcript|Don't remove this notice too soon.}}
:[Ponytail is walking into her room. The room has a bed, a set of drawers and a large sci-fi device mounted on the ceiling. Hairy is standing in the room, pointing up at the device.]
:Hairy: What's that device?
:Ponytail: Part of the supernova early warning system.
:Ponytail: There hasn't been a Milky Way supernova in over a century.
:Ponytail: Astronomers don't want to miss the next one.

:[Close up of Ponytail, now sitting on the end of the bed]
:Ponytail: 20 years ago, we set up a supernova alert system using neutrino detectors.
:Ponytail: It should give us a few hours' advance notice.

:[In a frame-less panel the view zooms back out, showing Ponytail and Hairy.]
:Ponytail: If it ever goes off, every astronomer on earth will scramble to point their equipment at the sky.
:Hairy: Oh, OK. So is that a detector? Or some kind of telescope?

:[The panel moves to the right, showing Hairy walking away. Ponytail is still on the end of the bed, raising a clenched fist for dramatic effect.]
:Ponytail: Fireworks launcher.
:Ponytail: I '''''refuse''''' to sleep through a supernova.
:Hairy: I think I'll spend the night at my place instead.

==Trivia==
The word "off" is misspelled as "of" in the title text.

{{comic discussion}}<noinclude>

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Astronomy]]

explain xkcd - User contributions [en]

3207: Bad Map Projection: Zero Declination

3208: SNEWS