Wikipedia:Reference desk/Archives/Science/2021 November 11

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November 11

Atmospheric escape from moons; what effects of their host planet's gravity?

So there is a lot of scientific literature on atmospheric escape (the process by which atmospheres of planets slowly evaporate into space) and the role radiation, gravity etc. play but I can't find anything specific about moons. The thing I wonder about is whether being a moon rather than a planet would change the escape process; after all the escaping atmosphere would have to overcome not just the gravity of the moon but also that of the planet. Jo-Jo Eumerus (talk) 16:44, 11 November 2021 (UTC)

There's definitely literature on atmospheric escape from moons such as Titan: you can see some discussion in atmosphere of Titan and the references there. The presence of the planet can be important, for example in the Galilean moons [1], [2], where the Jovian magnetosphere contributes to sputtering. From the abstracts they describe some portion leaving the Jovian system and another portion contributing to the Jovian magnetosphere. --Amble (talk) 17:27, 11 November 2021 (UTC)

• ec The article on Io (moon) says that Jupiter's "magnetosphere of Jupiter sweeps up gases and dust from Io's thin atmosphere at a rate of 1 tonne per second" and "end up in various neutral (non-ionized) clouds and radiation belts in Jupiter's magnetosphere and, in some cases, are eventually ejected from the Jovian system". Perhaps some gets drawn down into Jupiter too. Abductive (reasoning) 17:33, 11 November 2021 (UTC)

That's for the magnetosphere; does Jupiter's gravity also play a role? This is an old paper speculating about the effect of Saturn's gravity on Titam.JoJo Eumerus mobile (main talk) 17:40, 11 November 2021 (UTC)

That's interesting. I hadn't heard about the idea of recapture by Titan. --Amble (talk) 17:47, 11 November 2021 (UTC)

To answer this question you need to compare the vertical extent of the atmosphere to Hill radius of the satellite in the gravity field of the planet. Ruslik_Zero 20:39, 11 November 2021 (UTC)

Gunk buildup on computer mouse

Why mouse is particularly prone to gunk buildup (on the top and sides) compared to some other frequently used items, such as pens, cup handles, kitchen utensils, etc? Does it have something to do with material the mouse is made from? 212.180.235.46 (talk) 17:57, 11 November 2021 (UTC)

I'd guess it has to do with differences in use. You keep your hands in near constant contact with a mouse for hours on end, day after day, and don't necessarily wash your hands before each use. You definitely don't clean your mouse between every use, and may go days or weeks or longer without cleaning it. You keep your hands on the mouse even as your palms get sweaty. Now, compare that to the other items you listed. You only use a pen in brief spurts while writing. You only hold the cup handle for brief moments while taking a sip, and you probably wash your cup between every beverage. You only hold kitchen utensils for the brief moments of usage, i.e. knife and fork while cutting steak, but that doesn't last for hours on end. You then wash them between meals. Many/most (hopefully) also wash their hands before starting a meal. --OuroborosCobra (talk) 19:25, 11 November 2021 (UTC)

Storage and dust might also be factors, as the other items listed are not stored in ways that so enable the accumulation of dust (which could mix with sweat to form the 'gunk'). PaleCloudedWhite (talk) 20:52, 11 November 2021 (UTC)

I suppose the main ingredient is accumulated sebum mixed with dead skin cells and fine dust. The surface of a mouse should not be slippery and is often somewhat matt (non-glossy), which may facilitate the adhesion of sebum – in addition to the factors already mentioned.  --Lambiam 21:24, 11 November 2021 (UTC)

If it's salty there's dried sweat too. I don't feel like tasting. Sagittarian Milky Way (talk) 23:09, 11 November 2021 (UTC)

That would be WP:ORIGINAL RESEARCH :-) Alansplodge (talk) 11:52, 12 November 2021 (UTC)

As a chemist, I must encourage everyone to NEVER TASTE THE SCIENCE :-D --OuroborosCobra (talk) 20:46, 12 November 2021 (UTC)

Well, some geologists, archaeologist, and paleontologists might disagree with you.--Khajidha (talk) 15:59, 18 November 2021 (UTC)

What's the basis of your premise? ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:04, 13 November 2021 (UTC)

Sets of chemical elements

This may seem a funny question at first glance, but is it, in fact, rather a coincidence that the number of categories in the most common classification of element sets in the periodic system is exactly ten, or were these sets deliberately designed in a manner to amount to the round figure of ten? (Cf. Names for sets of chemical elements, however, listing twelve IUPAC-recommended classes with a pertinent citation, which lacks a corresponding reference entry, though.)--Hildeoc (talk) 22:22, 11 November 2021 (UTC)

Some of the 12 overlap. Sagittarian Milky Way (talk) 22:51, 11 November 2021 (UTC)

While it's true that 10 is a nice round number in the decimal system, a coincidence requires two (or more) events or occurrences. I don't think that the number of categories in the periodic table can be classed as a remarkable concurrence in and of itself. nagualdesign 23:09, 11 November 2021 (UTC)

There are other ways to cut up the periodic table too. Could be by group (column) eg group 12 element, or by period (row) eg period 6. Yet another way to classify could be solid, liquid or gas. In geochemistry they can be grouped as lithophile, siderophile, chalcophile etc in the Goldschmidt classification. The classification has to be useful, grouping similar things together. Graeme Bartlett (talk) 10:47, 12 November 2021 (UTC)

@Nagualdesign: Thanks for your interest. Well, the two occurrences could be described as the fact that (1) the number of sets amounts to ten as the "round" number per se, and that (2) these sets, in return, include all elements of the periodic system – i.e. both occurrences signifying completeness, with the former using a very common numeric representation of completeness / perfection …--Hildeoc (talk) 22:49, 13 November 2021 (UTC)

I'm not sure what you mean by "a very common numeric representation of completeness / perfection". As I'm sure you're aware, the decimal system owes its origins to the simple fact that humans have 10 fingers (including the thumbs) to count with. So if your question could be reworded as "Is it a coincidence that this particular way of grouping chemical elements uses the same number of categories as humans have fingers?" then yes, that's obviously very much a coincidence, much as anything else that just so happens to number 10 is a 'coincidence'. There's really nothing special about the number 10, and as Graeme pointed out, there are other ways of classifying elements. nagualdesign 22:54, 14 November 2021 (UTC)