Wikipedia:Reference desk/Archives/Science/2018 March 25

= March 25 =

What model of Atmos clock is this?
I am trying to figure out what the model number for this Atmos clock is. --Guy Macon (talk) 05:45, 25 March 2018 (UTC)


 * (...Sound of Crickets...) --Guy Macon (talk) 02:26, 26 March 2018 (UTC)
 * "Choip!" (Brooklyn cricket) ←Baseball Bugs What's up, Doc? carrots→ 04:43, 26 March 2018 (UTC)


 * It's an Atmos Classique Transparente Phases de Lune, part number starts with 580, perhaps? Abductive  (reasoning) 04:14, 26 March 2018 (UTC)

bug identification
I've seen quite a few specimens of this kind of insect over the course of the past month in Israel. They fly rather erratically (bouncing around) and are easy to swat when they've landed (unlike, for example, houseflies, which easily dart away). They are, I'd say, perhaps around five centimeters in diameter including the bent legs. What are they, please?&mdash;msh210&#x2120; 10:30, 25 March 2018 (UTC)
 * Almost certainly a Crane fly. Rojomoke (talk) 11:14, 25 March 2018 (UTC)
 * Many thanks.&mdash;msh210&#x2120; 12:18, 25 March 2018 (UTC)
 * Known to English children as "Daddy longlegs" (confusingly, a name also given to Opiliones or "harvestmen" who are even more well-endowed in the leg department). Alansplodge (talk) 16:23, 25 March 2018 (UTC)
 * And some children here in the states too. Then there's some Americans who use "daddy long legs" for the Pholcidae cellar spiders. So while best bet is to use the Latin, harvestmen/crane fly/cellar spider are common names that avoid the problems with daddy long legs. SemanticMantis (talk) 15:45, 27 March 2018 (UTC)
 * To complete the discussion of inter-related colloquial designations, crane flies are also often called 'mosquito hawks' in various North American locales, owing to a superficial similarity to mosquitoes and the thoroughly inaccurate (but still quite pervasive) belief that they hunt mosquitoes. However, as with the 'daddy long-legs' moniker, Tipulidae shares the name 'mosquito hawk' with several other species--most notably dragonflies, which actually do hunt mosquitoes.  Sheesh, past time to start educating our youth on binomens from an early age, huh? Snow let's rap 22:17, 28 March 2018 (UTC)
 * My great-grandfather was an entomologist in the 19th century. Part of his collection of specimens is stored in the Plymouth Museum; it includes tray after tray of carefully labelled crane fly wings, all similar but apparently from different species which can only be told apart by different patterns in the wing membranes. Alansplodge (talk) 10:06, 29 March 2018 (UTC)
 * Yes, that is true of a great many insects; sometimes wing cell morphology is one of the few easily-observable (well, easily-observable only in the relative sense, I suppose!) taxonomical features by which to distinguish between closely related species. In any event, talk about meticulous and painstaking work; we take modern tools so much for granted! Sno<b style="color: #b2dffe;">w</b> <b style="color: #d4143a">let's rap</b> 02:34, 30 March 2018 (UTC)

DST and sun
During the daylight saving time, when the clocks are advanced further (one hour forward, in particular), does it mean that the sun reaches zenith at 13:00 local time instead of theoretical 12:00, as shown by sundial? Thanks. 212.180.235.46 (talk) 15:25, 25 March 2018 (UTC)


 * No. Full width time zones have to be at least 30 minutes in error on at least one edge (often more since states, counties and countries don't end at exactly the right longitude and people like to shift them west for fake DST). And a modern clock has a very consistent pace compared to a sundial, it's only an average of what the sundial says. Sundials and local solar time can be up to 16 minutes wrong (more in some of the far future and past) which currently occurs in November, the same month DST ends in North America. The band where noon is 13:00 to the second is about 300 meters wide at European latitudes and could be kilometers away the next day. Sagittarian Milky Way (talk) 16:57, 25 March 2018 (UTC)
 * Yes, this is true that when you advance clocks by one hour the true solar noon happens later by one hour. Ruslik_ Zero 20:00, 25 March 2018 (UTC)


 * That's a most unfortunate way of putting it. The solar noon doesn't change, but the time we attribute to it advances because of the clock being advanced. This doesn't happen with a normal sundial, though it would be possible to swivel it around a central column to advance or retard it. Akld guy (talk) 22:30, 25 March 2018 (UTC)


 * Right, and as noted above, solar noon is often not at noon local time in the first place. For an extreme case, Time in China, the People's Republic of China uses only one time zone "officially", so in its west the official clock time is hours ahead of solar time. --47.146.60.177 (talk) 20:17, 25 March 2018 (UTC)


 * Further to earlier answers, the fact that the Earth's orbit around the Sun is not circular, but elliptical, means that the Earth's orbital speed varies over the year, resulting in actual or apparent noon (when the Sun actually appears on the meridian – i.e. due north or south depending on the hemisphere one is in) often being earlier or later that what is indicated by unvarying-rate clocks, which show the averaged mean solar time, by up to a quarter of an hour. The mathematical description of this is called the Equation of time, which article should explain this in detail. {The poster formerly known as 87.81.230.195} 2.218.14.51 (talk) 00:47, 26 March 2018 (UTC)