The phenomenon of an atmospheric aurora (known as aurora borealis in the northern hemisphere and aurora australis in the southern hemisphere) occurs as a result of charged particles emitted by the sun interacting with the Earth's magnetic field. The magnetic field funnels the charged particles towards the polar regions of the earth. At some point, the flow of particles hits the atmosphere, where the particles interact with the molecules of the gases which make up the atmosphere and add to those molecules' energy. Those molecules subsequently release the added energy in the form of light, which is observed as an aurora.
Where in the atmosphere the aurora occurs is related to the quantity and energy of the particles being emitted by the sun. Under normal circumstances, this occurs in high latitudes relatively close to the poles. In less common circumstances of more intense solar activity such as a a solar flare or coronal mass ejection (CME), the charged particles are traveling faster and get diverted less by the Earth's magnetic field, so auroras will occur at lower latitudes. This comic indicates both the rarity with which this would occur and the impact it would have on people.
Polar latitudes: Normal; auroras typically can be seen in these high latitudes.
Subpolar latitudes: (e.g., southern Canada/northern US, most of northern Europe, northern half of Asia, and numerous small islands in the southern hemisphere) Happens frequently enough to be unconcerned but uncommon enough to be notable and interesting. About a week before the publication of this comic, on Wednesday, November 20, 2019, aurora activity was visible in the northern United States and southern Canada.
Subtropical/Tropical latitudes: Charged particles of sufficient energy to cause auroras at this latitude are very rare and have happened on only a few occasions in recorded history, and not during the space age. A particularly strong one was the solar storm of 1859, which caused failure of telegraph systems all over Europe and North America and in some cases gave telegraph operators electric shocks. An event of that magnitude today would likely interfere with the functioning of electronic systems in orbit, possibly to the point of disabling them entirely, and would cause widespread damage to our now highly electrified world.
Equatorial latitudes: Auroras have never been recorded here, so all scientific inquiry into what the effect would be on the Earth in general, and on life itself, is purely theoretical. Were this to actually occur, those theories could be proven or disproven based on actual observations (presuming all observers have not been incapacitated or otherwise occupied by the complete breakdown of all electrical and electronic systems as the charged particles induce electric currents in conducting objects). An event powerful enough to have auroras at equatorial latitudes would be extremely energetic and would probably cause very high levels of damage on Earth.
The title text comments on what would happen if auroras were seen in the equatorial band. arXiv.org is an electronic database of unreviewed, pre-print research papers. The astro-ph.SR sublist is a list of papers in the "Solar and Stellar Astrophysics" topic. So if auroras were seen in the middlemost band, there would be many requests to upload electronic publications on the subject, as well as actual electrical interference to the servers of the website. Randall may have been consulting this server for research on the comic, prompting this specific observation.
- [A drawing of a circle with six dashed lines dividing it into 7 segments with different width. Those at equal distance above and below the broadest middle segments have the same width. Each segment has a label. Above the circle there is a caption:]
- What it means if you see an aurora, by latitude.
- [The labels of the seven segments:]
- Cool and exciting
- Someone should go check on our satellites
- A bunch of open questions in solar-terrestrial physics are about to be answered
- Someone should go check on our satellites
- Cool and exciting
add a comment! ⋅ add a topic (use sparingly)! ⋅ refresh comments!
Hey guys. As you can tell by the edit logs, I'm removing a spam comment that was made in bad faith. I'm new here so please let me know what the actual procedure is for, ya know, spam deletion and logging.
Have an outstanding day, --OtterlyAmazin (talk) 03:46, 26 November 2019 (UTC)
- Great you removed this text. I guess if this account keeps doing such things it should be banned. Sadly we seem to have lost all contact to any admin of the page...? So I'm not sure how we could do anything. --Kynde (talk) 08:01, 26 November 2019 (UTC)
- Wow, yeah, that looks obnoxious, good job clearing it out, thanks! NiceGuy1 (talk) 04:39, 5 January 2020 (UTC)
Nobody talks about the visible shadow of the two lower texts? You can clearly see a layer of grey letters, not identical to the topmost layer, benath. 22.214.171.124 05:57, 26 November 2019 (UTC)
- I have no idea what you are talking about. I see no shadows on neither xkcd or the image uploaded here? Maybe it is your device that is making the shadows... --Kynde (talk) 08:01, 26 November 2019 (UTC)
- On the words Satelite and Exciting in the southern hemisphere it is most visible (but also on others) that there are greyish letters right next to the black ones, kinda like shadows. Maybe Randall copy pasted and changed it. Similar things of remains of erased parts have been visible before. (If someone thinks it is important, I can try to look it up, but I am not exactly sure where it was) --Lupo (talk) 08:38, 26 November 2019 (UTC)
- You're right. It's most visible on the right side of the loop in the 'S' at the end of 'Satellites' in the southern hemisphere, but you can also see it on the lower tip of 'C' and the upper tip of 'G' in 'Exciting'. However, I downloaded the image and used an image editor to up the contrast, and it turns out the grey letters are the exact same as the black ones, just in slightly different places and shapes. Presumably Randal didn't like his first attempt at lettering the comic and erased it and rewrote it. 126.96.36.199 05:58, 27 November 2019 (UTC)
- I see it most in "exciting", on the C and G. My theory: He wrote it manually, but didn't like it, or didn't like that it didn’t match the Northern Hemisphere version, used an erase tool that actually blends to the background colour, and Copied / Pasted it. Can anybody use a paint tool to see if the current version is now an exact match? NiceGuy1 (talk) 04:39, 5 January 2020 (UTC)
- That is known as "mustard". This term originated in the OTT, of course188.8.131.52 16:34, 27 November 2019 (UTC)
- What does this comment even mean? I have no idea what "OTT" means and what the term "mustard" refers to in either the comic or any previous comments! Can the OP or anyone else shed some light on it? Ianrbibtitlht (talk) 17:48, 27 November 2019 (UTC)
- The OTT (short for the One True Thread) is the unofficial nickname for the xkcd fora thread for Time (also known over there as the One True Comic (OTT for short). Mustard arose when some mistakes in colouration were made during Time's run that appeared as outlines is a faintly mustard-like colour. Hope that's of any help. 184.108.40.206 15:41, 28 November 2019 (UTC)
- Since this seems like it was meant to be a reply to the "shadow" comment above, I increased the indentation to show that better and hopefully clarify better. Thanks Mr/Ms 162.158, I was at a loss too. :) NiceGuy1 (talk) 04:45, 5 January 2020 (UTC)
Do we have any indication how much energy we're talking to see the aurora at the equator? or how that would physically work? 220.127.116.11 08:17, 26 November 2019 (UTC)
There has been an equatorial aurora exactly once in human history. Starfish Prime was an orbital nuclear detonation that, among other things, disabled multiple satellites and created a temporary artificial aurora 16° north. That is also likely what the sub-tropical band is referring to. 18.104.22.168 09:12, 26 November 2019 (UTC)
What should "Subpolar latitudes" include for the southern hemisphere? Southern Africa? Southern Australia? Since I'm in the northern hemisphere, I don't know what's appropriate for the other half of the world. Ianrbibtitlht (talk) 22:46, 26 November 2019 (UTC)
- Most of the subpolar latitudes of the southern hemisphere are ocean. Southern Australia is still subtropical. The southernmost parts of Chile and Argentina (Terra del Fuego) would qualify.
- umm, it is actually possible to see the aurora australis from the southern parts of Australia. https://www.abc.net.au/news/2019-06-14/aurora-australia-watching-and-photographing-the-southern-lights/11197868 and the southern parts of Australia, whilst capable of getting very warm in summer, are definitely not subtropicalBoatster (talk) 10:32, 2 December 2019 (UTC)
In Principal Skinner's kitchen: You are about to enjoy delicious steamed hams. ―TobyBartels (talk) 13:00, 5 December 2019 (UTC)
Saturn's out of place H3+ Aurorae and Ring Decay
Wondering if this might have been inspired by James O’Donoghue discovery of decay of Saturn's rings.
“I thought it could be some new band of aurora which had never been seen before or something entirely new. Those were the two options now, and both were amazing.”
Read more: https://www.smithsonianmag.com/science-nature/saturns-rings-are-slowly-disappearing-180972856/#dL7Me0SVImIcFSRq.99
The loss or reorientation of the magnetic field of the earth would probably result in frequent equatorial auroras.
22.214.171.124 11:59, 26 January 2020 (UTC)