Wikipedia:Reference desk/Archives/Science/2022 June 21

= June 21 =

Lines in front of Moon
I took these photos of the Moon a few days ago. What are the thin lines in front of the Moon - contrails? clouds? (Ignore the UFO in the lower left.) Bubba73 You talkin' to me? 01:30, 21 June 2022 (UTC)


 * The times are Eastern Time on June 15. Bubba73 You talkin' to me? 15:34, 21 June 2022 (UTC)


 * Obviously, the "UFO in the lower left" is a hologram projector. —2603:6081:1C00:1187:1807:C437:3907:422A (talk) 07:25, 21 June 2022 (UTC)
 * It's either a Jupiterean lens flare or he's a time traveler. Slight time travel. Sagittarian Milky Way (talk) 07:39, 21 June 2022 (UTC)
 * Or it's a lightbulb. Sagittarian Milky Way (talk) 07:42, 21 June 2022 (UTC)
 * Oh it's not today. The time on the camera is probably wrong. Or it's probably south of USA for that moon to be rising so early. Sagittarian Milky Way (talk) 08:01, 21 June 2022 (UTC)
 * Mountain Time Zone and near southeastermost Arizona? Hawaii? Sagittarian Milky Way (talk) 08:09, 21 June 2022 (UTC)
 * Judging from the position of the terminator, the picture was taken on 16 June around 4 UTC, give or take a few hours. 21:30 local time on the 15th somewhere at the longitude of the USA is plausible. If the moon was rising that early, the picture must have been taken at low latitude. I just compared the pictures to the simulation in Stellarium. Judging from the orientation of the moon and the time it rose, Jacksonville FL is plausible, or somewhere near Austin TX or in the southwest of New Mexico. For each time zone, there's a line running southwest-northeast where the moon rose at that time and the orientation of the moon tells us it must have been around 30° North latitude. Unfortunately, the pictures aren't very sharp. For Pacific time zone, it appears that this line reaches the coast too far north, all assuming the picture was taken this month. A nice puzzle, but OP can tell us exactly where the picture was taken.
 * As for those clouds, the thin lines look like a far-away contrail. It gets wider from the first image to the last. The cloud appears pretty much stationary with the moon rising behind it, an effect of the large distance of around 500km to the cloud. It's only about a degree above the horizon. There is some forward-scattering of light in some cirrostratus clouds visible around the moon, possibly older contrails. The other blob looks like a remnant of a cumulus cloud only a few tens of kilometres away or a man-made cloud from some chimney. It's clearly moving, without any significant forward-scattering of light. PiusImpavidus (talk) 10:48, 21 June 2022 (UTC)


 * Good analysis of the time and position! The photos were taken from St. Simons Island, on the east coast of Georgia (US state), latitude about 31 degrees.  Those times came from my camera - I need to check to see if they are accurate.  The Moon had just risen, so it is low in the horizon, with a lot of atmospheric distortion. Bubba73 You talkin' to me? 15:39, 21 June 2022 (UTC)
 * The times were about 1 hour off (camera still had EST) - corrected now (EDT on the evening of June 15). Bubba73 You talkin' to me? 15:46, 21 June 2022 (UTC)
 * Right, I found that Stellarium didn't properly apply DST either, so the position still fits. PiusImpavidus (talk) 16:17, 21 June 2022 (UTC)


 * Also, there are two thin lines in the upper right in the first photo. Bubba73 You talkin' to me? 15:48, 21 June 2022 (UTC)
 * Maybe there are two thin lines because this was a twinjet. Vertical separation between the lines appears to be around 1/40 of the altitude or about 250m. That's a bit much, but the wingtip vortices can move the trails apart and if the aircraft was banking, one trail would move up and the other down. My guess is that it was Air Europa flight 98 from Miami to Madrid, a Boeing 787-9 Dreamliner at 37000 feet, which made a right turn at about the right time and place. All those flights to the Norteastern US only fly about 300km away from your observing location and would appear a bit higher in the sky, at about 2 degrees. After a while, the trails from both engines merge. PiusImpavidus (talk) 17:01, 21 June 2022 (UTC)


 * You did some really good work on this! BTW, about the UFO - I couldn't tell what it was with the naked eye.  With my strong telephoto lens on my camera, I could tell that it was a shrimp boat, fishing at night with lights on.  Bubba73 You talkin' to me? 00:56, 23 June 2022 (UTC)
 * Identified non-flying object. Sagittarian Milky Way (talk) 02:24, 23 June 2022 (UTC)


 * Identified Floating Object. Bubba73 You talkin' to me? 06:48, 25 June 2022 (UTC)

How can rectum be hotter than core?
Sagittarian Milky Way (talk) 07:45, 21 June 2022 (UTC)
 * It is not as if there is a heat-producing core reactor, with the heat being spread to the rest of the body by thermal conduction. All living tissue produces heat, mainly through metabolic activity. I don’t know how the "core" temperature measurements presented in the Welch Allyn chart were obtained; perhaps from Houdas, Y., Ring, E. F. J; Human Body Temperature, Its Measurement and Regulation; 1982; pp. 81–87, which they cite as a source. I imagine that the temperatures in the liver and the pancreas are not necessarily the same. In any case, I cannot think of an argument why the rectal temperature should not exceed core temperature. --Lambiam 08:41, 21 June 2022 (UTC)
 * The difference is consistently 0.4 degrees F? That's quite small. Could it simply be explained by sampling error? Martinevans123 (talk) 08:46, 21 June 2022 (UTC)
 * That page nowhere defines 'core' temperature. Where and how is it measured? -- Verbarson talkedits 08:50, 21 June 2022 (UTC)
 * Houdas and Ring give this definition, from the standard established by the International Union of Physiological Sciences and published as a "Glossary of Terms for Thermal Physiology": Core temperature or deep body temperature  The mean temperature of the tissues at a depth below that which is affected directly by a change in the temperature gradient through peripheral tissues. The "Glossary" adds this: Mean core temperature cannot be measured accurately, and is generally represented by a specified core temperature, e.g., that of the rectum. [°C] That really raises the question where Welch Allyn got their numbers from.  --Lambiam 14:00, 21 June 2022 (UTC)
 * A rare case in which the numbers were literally pulled out of their arses?
 * (I'll get me coat) {The poster formerly known as 87.81.230.195} 90.201.73.76 (talk) 22:58, 22 June 2022 (UTC)
 * I incorrectly assumed core temperature was the point of highest temperature in the human. Where would that be? Liver? Furthest point from the skin? Where's that? Sagittarian Milky Way (talk) 20:07, 21 June 2022 (UTC)
 * If the environment is very hot it will be the skin? Presumably all these standard temperatures are measured in a defined benign environment? Martinevans123 (talk) 20:11, 21 June 2022 (UTC)
 * If the skin is the hottest, the body temperature must be rising (unless there's some internal cooling, like breathing really cold air or pumping cold water through the intestinal tract). There would be nowhere for the waste heat to go. Not something you can survive for long. PiusImpavidus (talk) 18:42, 22 June 2022 (UTC)

I just saw this today, see what you think! https://www.sciencealert.com/new-research-shows-your-brain-can-run-a-lot-hotter-than-we-ever-realized 211.30.161.13 (talk) 07:08, 22 June 2022 (UTC)
 * It gives a new sense to the term hothead. --Lambiam 07:59, 22 June 2022 (UTC)
 * Goodness me... if that means getting a flattened Rubik's cube stuck in me swede, I think I'd rather put up with a hot rectum, thanks. Martinevans123 (talk) 18:47, 22 June 2022 (UTC)

Precordial catch syndrome
Already read Precordial catch syndrome, what more could you share about this one? How is it compared to Costochondritis?-- Exclusive Editor  Notify Me! 17:03, 21 June 2022 (UTC)
 * While the pain of costochondritis can be severe, it does not appear suddenly like the sharp, stabbing pain of precordial catches. Bouts of the latter also disappear quickly, in a matter of minutes, whereas the pain of costochondritis tends to linger for extended periods, possibly for several months. Since the same symptoms (for either of these conditions) may be caused by conditions that are a medical emergency, it is cautious, if experienced, to see a medical professional, who can also give advice on pain management. --Lambiam 20:02, 21 June 2022 (UTC)

JP-7
Did JP-7 contain any natural or synthetic diamantane homologues? 2601:646:8A81:6070:F5AD:972D:6C45:ADB3 (talk) 22:49, 21 June 2022 (UTC)


 * The original JP-7 recipe dates to 1955; the first laboratory synthesis of diamantane was in 1965&mdash;so I'm going to go out on a limb and speculate that the JP-7 spec didn't call for synthetic diamantane derivatives.
 * I can't find a copy of the original 1955 specifications, but the relatively recent MIL-DTL-38219D, DETAIL SPECIFICATION: TURBINE FUEL, LOW VOLATILITY, JP-7 doesn't mention diamantane or other diamondoids and their derivatives specifically.
 * The JP-7 spec does call for low volatility and high thermal stability (which is unsurprising, given its working environment). Naturally-occurring diamondoid compounds certainly wouldn't hurt in achieving those necessary stability and volatility thresholds, so I wouldn't be surprised if there were trace amounts of natural diamandoids (including diamantane species) in JP-7. TenOfAllTrades(talk) 12:00, 23 June 2022 (UTC)
 * Thanks! So, probably not in the original recipe, is that correct?  (But if we need to make a new fuel with similar specs to JP-7, then synthetic diamantanes would very likely be one of the ingredients!) 2601:646:8A81:6070:640D:F1C9:3B1D:1044 (talk) 02:25, 24 June 2022 (UTC)