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July 12

Variation in time of dusk

In Frederick Forsyth's Day Of The Jackal, one attempt on De Gaulle's life failed because it was darker than expected, so his car was on the gunmen before they realised. The organiser had used a calendar of the previous year to give the time of dusk (20.35 on 22 August 1961), but on the same date in 1962 dusk was at 20.10, fifteen minutes earlier. Supposedly this was an astronomical fact, nothing to do with local weather conditions. Is such an annual variation possible? If so, what is the pattern, as continuing movement in one direction is not possible? →2A00:23C6:AA08:E500:41E5:1052:C726:931C (talk) 11:52, 12 July 2020 (UTC)

Good catch! Same-date year-to-year changes are primarily due to the difference between the tropical year the and calendar year and are never larger than the day-to-day change, for which fifteen minutes is way too big for Paris's moderate latitude of 49°. (Expect a same-date year-to-year change to be roughly 3/4 of the day-to-day change if there is an intervening leap day and 1/4 of the day-to-day change in the opposite direction if there isn't.)

The NOAA Improved Sunrise/Sunset Calculator doesn't give dusk or twilight times, but does gives the following apparent sunset times for Paris:

• 1961-08-22: Sunrise=05:51 Sunset=19:52
• 1962-08-22: Sunrise=05:51 Sunset=19:53

Timeanddate.com does calculate twilight times, and gives:

• 1961-08-22: Sunrise=05:52 Sunset=19:53 End of Civil Twilight=20:27
• 1962-08-22: Sunrise=05:52 Sunset=19:53 End of Civil Twilight=20:27

I don't know if the 1 minute discrepancy is due to differences in the calculators or in their precise chosen location for Paris, but they are rounding errors compared to Forsyth's claimed 15 minutes. -- ToE 13:41, 12 July 2020 (UTC)

We have a description of the actual assassination attempt at Jean Bastien-Thiry#Assassination attempt, and to a lesser extent at Charles de Gaulle#Assassination attempts. From the former:

On 22 August 1962, while Bastien-Thiry functioned as a lookout, de Gaulle's car (a Citroën DS) and some nearby shops were raked with machine-gun fire. De Gaulle and his wife and entourage escaped, uninjured. After the attempt, holes from fourteen bullets were found in the president's vehicle, one of which barely missed the president's head; another twenty were found to have struck the nearby Café Trianon; and an additional 187 spent shell casings were found on the pavement. De Gaulle was said to have credited the unusual resilience of the Citroën DS with saving his life: even though the shots had punctured two of the armoured tires, the car escaped at full speed.

-- ToE 13:52, 12 July 2020 (UTC)

Ummmmm.... the difference between those two times is 25 minutes, not 15.--Khajidha (talk) 13:56, 12 July 2020 (UTC)

Yes, I've just noticed that, so even more unreasonable. Thanks for clarification.→2A00:23C6:AA08:E500:75AB:AB90:72E8:F3BF (talk) 14:02, 12 July 2020 (UTC)

And this is why we don't replace Gregorian with leap week calenders, having the same calendar every year is not worth fake dates. Sagittarian Milky Way (talk) 14:04, 12 July 2020 (UTC)

Anyway, having the same calendar every year would be less convenient than the present system for multiple reasons. --174.89.49.204 (talk) 16:27, 13 July 2020 (UTC)

It's not even the same every year cause 52/293rds of years are 371 days, if and only if the remainder of ( 52 * 4 digit year + 146 ) / 293 is less than 52. Simple. /s Sagittarian Milky Way (talk) 03:41, 14 July 2020 (UTC)

• fr-Wikipedia has an article about that assassination attempt. It says the shooting starts at 20:20 but is otherwise silent on the luminosity conditions. It also says Bastien-Thiry was posted as a lookout and gave the signal by waving a newspaper, from which one could infer it was not too dark yet. The relevant sources are not online (refs 18 to 22 in the fr article) so I did not check them. Tigraan^{Click here to contact me} 12:49, 13 July 2020 (UTC)

I presume that B-T waved the paper when he first saw the car, which in view of the conditions may well have been when it was nearly at him. The gunmen would have assumed that he did so at the agreed distance and that they had time to aim, and would have been totally disoriented by the sudden appearance of the black Citroen travelling nearly head-on at 70 mph. A white newspaper being waved transversely would have been visible in relative gloom. →2A00:23C6:AA08:E500:789B:13C:EAB8:733B (talk) 21:43, 15 July 2020 (UTC)

Analemma would be a good read for this topic. Specifically this is roughly the extent of the 12-month cycle of the deviations of clock noon vs. astronomical noon (Sun in zenith). This will probably dominate the day-to-day changes in sunset times. (For example I live on the 46th parallel and earliest sunset comes more than a month before the latest sunrise).

However, in more northern latitudes near the polar circle, sunrise/sunset times don't follow a sinusoidal-like pattern and day-to-day sunset time variations near the polar day/night onset are much bigger. Being a day off due to the tropical year wandering could definitely mean screwing up by 25 minutes. For example using the NOAA calculator above: in Thule (Greenland), on 23 August 2016 the sun rose at 2:40, but on 23 August 2015 sunrise was already at 2:17. 93.136.16.89 (talk) 18:13, 16 July 2020 (UTC)

July 13

Person claims to sleep just a few hours a week

[1] Is that even slightly believable? Thanks. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 06:52, 13 July 2020 (UTC)

• Not without a better source than a random forum post. Per our article, self-reported sleep duration is only moderately correlated with actual sleep time as measured by actigraphy, and those affected with sleep state misperception may typically report having slept only four hours despite having slept a full eight hours. (I know the random forum post claims to have evidence that they were actually awake and functioning, but the post also ends with "now I found a way to actually sleep and my life is much better" which makes me extremely suspicious of all the previous claims - if they did need that presumably the actual doctors that examined them would have suggested something of the sort.)

A cursory search on Google Scholar reveals multiple studies showing a positive correlation between sleeping less than ~7h/day and various health risks, but this does not answer the question of whether some humans (even a small fraction of the general population that would not appear in average stats) can sleep less than an amount X per day and still be functional. Tigraan^{Click here to contact me} 12:22, 13 July 2020 (UTC)

There are some genetic conditions which result in a normal sleep length of 6 hours and this paper implies that sleep needs tend to be overestimated as most methods to trigger sleep deprivation also trigger stress which acts as a confounding factor. Jo-Jo Eumerus (talk) 12:28, 13 July 2020 (UTC)

Unless someone has Fatal familial insomnia, Mother Nature usually wins the sleep deprivation battle. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:14, 13 July 2020 (UTC)

Well all I have to say to that is...is...Zzzzzzzzzzzzzzzzzzzzzzz.... --Guy Macon (talk) 19:28, 13 July 2020 (UTC)

Being in STEM grad-school or being a new parent are generally considered good pools of data for minimal sleep for days on end. DMacks (talk) 19:39, 13 July 2020 (UTC)

How many Lumens?

While looking for a good headlamp for my night runs, I came across a large amount of lamps in AliExpress and in Amazon, claiming to emit as much as 8000, 10000 and even 12000 Lm. On the other hand, some highly recommended headlamps like this one declare a light output of 450 Lm. What is going on? Gil_mo (talk) 21:46, 13 July 2020 (UTC)

A clear 100 watt incandescent tops out in the 1800 lumen area and needs 120 volts and 0.83333 amps. 2020 LEDs would need not much less (volts multiplied by amps) to produce 12 kilolumen. Did you know early 21st century New York City streetlights on middle class streets with 1 resident per 4 or 5 inches of streetfront were usually only 150 watts? And many times brighter than a 150 watt incandescent? The amount of lumens they're claiming here is almost that bright. Sagittarian Milky Way (talk) 01:32, 14 July 2020 (UTC)

The concept of a 10000 lumen headlamp is ridiculous and the 450 lumen one would probably heat up uncomfortably if you kept it on high power for a long time while running. If you got it and used it in a low (100 lumen) setting it will likely be fine. LEDs are fantastically more efficient than incandescents though. And old fashioned two cell flashlight (KPR2 krypton bulb) may have made 20 or 30 lumens. A car headlamp makes around 500 lumens. You probably don't want a super bright headlamp for running since it will mess up your night vision. You just want to see where you're going and not run into stuff. Use the low setting and have the high available if you want to light up something in the distance. The very best LED's today make around 200 lumens per watt of electrical power so you can figure out what a 10000 lumen light would do to batteries. They might have meant 10000 candlepower which is fairly meaningless since you can get it arbitrarily high by focusing the beam to a tiny spot. 2602:24A:DE47:BB20:50DE:F402:42A6:A17D (talk) 05:20, 14 July 2020 (UTC)

A further consideration might be how much one wants to dazzle any pedestrians and motorists whom one is approaching. I have sometimes had to stop my car because an oncoming cyclist on the opposite side of the road and a considerable distance away had an LED headlight so bright (and so mis-aligned) that I could not see anything at all in front of me. {The poster formerly known as 87.81.230.195} 90.200.41.197 (talk) 08:30, 14 July 2020 (UTC)

I would like to second this, this is an everyday problem for me (a cyclist - doesn't just apply to pedestrians and motorists!) in winter. Your light - whichever you end up getting) needs to be aimed mostly downwards at the road some distance in front of you, or it will be a safety hazard. Fgf10 (talk) 09:23, 14 July 2020 (UTC)

(OP) So, it seems that the 10000 lumens advertised would light up a stadium, right? To be blunt, are they lying, all hundreds of sellers? Gil_mo (talk) 09:25, 14 July 2020 (UTC)

Electrical engineer here.

Here is a 1500W LED Stadium Flood Light that puts out 225,000 lumens:[2] (Click on the specifications link.), It costs $4,579.00. They make a 12V model so you can you can mount a pair of them on your monster truck (assuming that you have 250 amps at 12V available...)

You can buy a single LED that puts out 2,000 Lumens[3] It will cost you around $10 and you will need to hire a good engineer to design the driver circuitry and the heat sink. We are way past "put a resistor in series" territory here.

--Guy Macon (talk) 13:33, 14 July 2020 (UTC)

(OP) My question again: are they lying, all hundreds of sellers? Gil_mo (talk) 14:16, 14 July 2020 (UTC)

Does it have a single LED? Does it have a Lumen figure much larger than 2000? If so they are lying bastards. Nobody make an LED that puts out much more than 2000 Lumens. Four LEDs? 8000 Lumens max. (Make sure you aren't accidentally looking a HID, which puts out more from a single lamp than an LED.) Buy from a reputable vendor such as Diode Dynamics, and you won't get lied to. Hundreds of lying sellers is nothing new. Most of the time they are a handful of lying sellers with hundreds of identities.

Do take a look in AliExpress by searching for "head lamp LED". You'll even find a 300000 Lm piece. Gil_mo (talk) 15:12, 14 July 2020 (UTC)

Why would anyone even want the light of 200 frosted hundred watt incandescents or like literally 20 fairly bright streetlights in a headlamp? Sagittarian Milky Way (talk) 16:44, 14 July 2020 (UTC)

Someone who wants the police to impound their car as being a hazard on the road? A little too bright and you get a ticket. Way too bright and the take away your car and leave you standing alone on the street. Hope you remembered to charge that cell phone!

There is a place for brighter lights, and that's when you are in a specialized vehicle traveling off road, or an emergency vehicle that has stopped and is illuminating an accident or crime scene. But even they don't use bright headlamps; wrong pattern. They use things like this: [ https://www.diodedynamics.com/stage-series-42-white-light-bar.html ]. In California you have to cover the off-road lights with an opaque cover when driving on the road. I have never seen a light bar sold in California that didn't have a cover in the box; perhaps that is a legal requirement to sell in California? --Guy Macon (talk)

You may be interested in my new invention, the Dark Emitting Diode, or DED. These are commonly referred to as "Dead LED's", and are built on the technology used in my my inoperational amplifier, write-only-memory, and TTL Never gates. I even have a procedure for turning any LED into a DED, and a white paper for creating your very own single-shot smoke emitting diode out of any standard diode. --Guy Macon (talk) 14:51, 14 July 2020 (UTC)

Sell me 1000 DEDs so I could darken my room :)

Sellers are playing on the fact that 99% of people buying a headlamp won't have a clue what a lumen looks like. All they want is the best brightness for their bucks, so they click on the biggest number. As long as they're happy with the product they won't want the bother of returning it.--Shantavira|^{feed me} 09:56, 15 July 2020 (UTC)

July 14

Earthquakes can be predicted?

See https://phys.org/news/2020-07-math-formulas-earthquakes.html --83.73.199.185 (talk) 15:29, 14 July 2020 (UTC)

I will believe it when they predict their second earthquake. --Guy Macon (talk) 18:19, 14 July 2020 (UTC)

They still have to (successfully) predict their first. The scientific article reported on ("Postseismic deformation following the 2015 Mw7.8 Gorkha (Nepal) earthquake: new GPS data, kinematic and dynamic models, and the roles of afterslip and viscoelastic relaxation") does not even hint at the possibility of using their new models for earthquake prediction.  --Lambiam 14:23, 17 July 2020 (UTC)

Earthquakes have been occasionally scientifically predicted. For example the 1975 Haicheng earthquake was preceded by a successful mass evacuation 12 hours before the event. The problem is of course finding a prediction method that works on more than a few freak cases. To make an analogy, we have a radar already, but it only happens to work on a tiny sliver of the sky. 93.136.16.89 (talk) 17:53, 16 July 2020 (UTC)

From the Phys.org article linked to by the OP: "A lot of time and effort has been spent over the past several decades trying to figure out a way to predict when a major earthquake will strike, but to date, such efforts have come up short. In this new effort, the researchers have taken another approach to the problem: using math." Who would've thunk that math could be useful in developing a predictive formula?  --Lambiam 14:23, 17 July 2020 (UTC)

Enthalpies of carbonate precipitation from brine

How can one obtain a list of the known precipitates of carbonate from brine, and their enthalpies, including electrochemical processing of seawater?

This is related to a question from a few weeks ago. EllenCT (talk) 19:13, 14 July 2020 (UTC)

This question must be https://en.wikipedia.org/w/index.php?title=Wikipedia:Reference_desk/Science&oldid=964496927#Fixing_ocean_carbonate

Naturally calcium carbonate is precipitated from sea water, and also when it is concentrated by evaporation. Magnesium carbonate or dolomite are also possible solids. But you would have to add calcium or magnesium ions to make much more of this precipitate. This might come about from rock weathering. But none of this is answering your question. The easiest way as per original question would be for some natural process to do it. Perhaps this can be encouraged by making a favourable place for reefs (coral, shell, bacterial) to grow. But it will likely be limited by calcium in the water. Graeme Bartlett (talk) 00:06, 15 July 2020 (UTC)

If you can tell what they are talking about Petrou, Athinoula L.; Terzidaki, Athina (August 2014). "Calcium carbonate and calcium sulfate precipitation, crystallization and dissolution: Evidence for the activated steps and the mechanisms from the enthalpy and entropy of activation values". Chemical Geology. 381: 144–153. doi:10.1016/j.chemgeo.2014.05.018. discusses it. The NaCl makes CaCO₃ harder to crystallise.

And it is even more complex as the solids can be vaterite, aragonite calcite or amorphous calcium carbonate (which also contains water). Different energy is involved in seeding a crystal compared to growing one.Du, Huachuan; Amstad, Esther (27 January 2020). "Water: How Does It Influence the CaCO3 Formation?". Angewandte Chemie International Edition. 59 (5): 1798–1816. doi:10.1002/anie.201903662. Note enzymes can assist in crystallisation in organisms eg you probably have otoconin to make your ear dust. Graeme Bartlett (talk) 00:55, 15 July 2020 (UTC)

@Graeme Bartlett: you lost me on that last sentence, but I will study those sources. Have you heard of Mango Materials Co.? Here is a sequestration-constrained citation search on one of the CEO's recent publications. I can't imagine why there wouldn't be more efficient biotic precipitations in aqueous phase, since presumably that is where life arose and all. EllenCT (talk) 03:43, 17 July 2020 (UTC)

That last sentence is saying that it takes more energy to start off a crystal, than to deposit on it. If the energy was lower than crystals would not grow, and instead you would just get a proliferation of seeds. Graeme Bartlett (talk) 07:45, 17 July 2020 (UTC)

Gravity pulling apart moons

I understand that the moons of planets can be torn apart by gravity if they get too close to the planet about which they orbit. How's that work? Wouldn't gravity pull the moon down into the planet as one large solid rock? †dismas†|^(talk) 22:24, 14 July 2020 (UTC)

see tidal force, Mars’ Moon Phobos is Slowly Falling Apart. fiveby(zero) 22:30, 14 July 2020 (UTC)

Also see Roche limit. 85.76.78.180 (talk) 01:14, 15 July 2020 (UTC)

The key point is that "solid rock" is a description that only applies to small bodies, on which the tidal forces are small. Something the size of a moon is not solid enough to resist the forces. --174.89.49.204 (talk) 02:33, 15 July 2020 (UTC)

Imagine two rocks, on in a lower orbit and one in a higher orbit. Would they spend the same amount of time competing an orbit? No. Now hook them together with a rope. That will force them to spend the same amount of time competing an orbit but they would pull the rope tight trying. If the rope was too weak it would break. This is known as "tidal force" because it is the same thing that causes tides.

Now imagine the same two rocks sitting on the surface of the moon, one on the side facing earth and the other on the far side. Instead of the rope you have the moon's gravity that stops them from taking separate paths.

In the case of the moon, gravity is stronger than the tidal force. Same thing with the earth, otherwise the tides would be so high that the water would escape the earth and orbit the sun independently. --Guy Macon (talk) 06:14, 15 July 2020 (UTC)

"Moon" is used for any astronomical body that orbits a planet regardless of size. Lots of moons in our solar system are small captured asteroids. --47.146.63.87 (talk) 08:26, 15 July 2020 (UTC)

It happens gradually, rather like slowly dismantling a building. Large moons aren't solid; they have liquid interiors, just as rocky planets do. Moons that are below the size necessary for planetary differentiation (or I guess technically uh, lunar differentiation?) generally are only loosely held-together "rubble piles", since gravity of course scales with mass. So, it only takes a small force continually applied to gradually pull the moon apart into a ring system, which will then continue to inspiral. According to the favored hypothesis, our Moon basically formed through this process in reverse: a planetary collision created a debris ring around Earth that then coalesced into the Moon, which has continued gradually moving further away from Earth due to Earth's tidal force. --47.146.63.87 (talk) 08:26, 15 July 2020 (UTC)

Even more to the point, a moon does not suddenly appear out of nowhere as a solid object. (Rare asteroid capture notwithstanding). Close moons are not torn apart, but rather they are prevented from coalescing into solid objects in the first place. Again, Roche limit is key. Close moons are not dismantled by anything because physics prevents them from existing. 85.76.78.136 (talk) 20:05, 15 July 2020 (UTC)

Nice theory, but it ignores the fact that many close moons used to be far moons. See [ https://www.nasa.gov/feature/goddard/phobos-is-falling-apart ] for details. --Guy Macon (talk) 20:29, 15 July 2020 (UTC)

Thank you, all! †dismas†|^(talk) 18:19, 16 July 2020 (UTC)

Annoyingly, that article says nothing (beyond "gravity") about why Phobos and Triton are falling. —Tamfang (talk) 01:36, 19 July 2020 (UTC)

I can clear that one up. On any planet or moon that is not tidally locked there are tides. Sometimes there are liquid oceans and the tides are easy to see. Sometimes the body is solid and it is hard to detect the periodic squeezing and stretching but it is there.

The tides use up energy. The moving water or stretching rock generates a certain amount of heat. Now ask yourself; where does that energy come from? Nothing is being burned. No isotopes are decaying. It happens even where there is no sunlight.

The answer is that the energy is "stolen" from the orbit. Every tide moves the body into a slightly lower, slightly lower-energy orbit, and that energy goes into the creating the tides. --Guy Macon (talk) 02:20, 19 July 2020 (UTC)

July 16

Organism knows an earthquake's toll?

How can it know? See https://www.nytimes.com/2020/07/14/science/earthquake-dna-genes-kelp.html --83.73.199.185 (talk) 07:30, 16 July 2020 (UTC)

There is nothing in that article that suggests an "organism knows an earthquake's toll". What is your question?--Shantavira|^{feed me} 09:24, 16 July 2020 (UTC)

At least it is in its DNA.--83.73.199.185 (talk) 13:28, 16 July 2020 (UTC)

There is. I already asked the question.--83.73.199.185 (talk) 09:51, 16 July 2020 (UTC)

As Shantavira says, there is no suggestion of knowledge or sentience. The kelp populations dispersed and evolved separately. The point of the genetic diversion marks the event. Interesting read though, thanks for posting Zindor (talk) 10:19, 16 July 2020 (UTC)

foreskin restoration by non-surgical methods B.C.

Is there documentation for foreskin restoration by non-surgical methods in the ancient time (before Christ (BC) or close to this time)? --ThePupil (talk) 19:28, 16 July 2020 (UTC)

See Uncircumcision: a historical review of preputial restoration - a summary is viewable. There's also a brief mention at Restoration device. Alansplodge (talk) 20:51, 16 July 2020 (UTC)

July 17

stye transmission window

Stye#Cause reads Sharing of washcloths or face towels should be curtailed, to avoid spreading the infection. Can the infection be spread after the stye has healed? When can towels be shared again? I have heard 10 days from the stye onset, but I cannot find a reliable source on Google (some websites even state that styes are not infectious). --62.98.105.176 (talk) 07:52, 17 July 2020 (UTC)

For your second question, sharing a towel sounds like a bad idea to me at any time.--Shantavira|^{feed me} 08:56, 17 July 2020 (UTC)

Please assume that's not an issue (people already living together, or sleeping together, with bigger infection vectors, usually sharing towels notwithstanding the risk of an occasional stye). I'm asking for information to add to the article, unrelated to a specific case. --62.98.105.176 (talk) 09:36, 17 July 2020 (UTC)

The advice not to share washcloths or face towels should be moved to section Stye#Prevention.  --Lambiam 13:47, 17 July 2020 (UTC)

This looks like a request for medical advice. The OP says it isn't, but that doesn't prove it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:16, 17 July 2020 (UTC)

To me it doesn't look like a request for medical advice, Bugs, and the OP specifically states that they're looking to improve the article. Can you prove that it is such a request? (Obviously not, and I'm not trying to be contrarian, I just think you're wrong.) {The poster formerly known as 87.81.230.195}

COVID deaths on weekends?

Typical graphs of COVID deaths or cases like I see here: COVID-19_pandemic_in_the_United_States#Progression_charts, see "No. of new daily cases" and "No. of new daily deaths" show regular up & down teeth features. Is this because of reporting differences on weekends? Or are people actually dying less on weekends? I can imagine maybe fewer diagnoses on weekends, but more actual weekend deaths doesn't really make sense to me. Staecker (talk) 12:10, 17 July 2020 (UTC)

@Staecker: See 'Weekend effect'. Cheers, Zindor (talk) 12:48, 17 July 2020 (UTC)

No. The Weekend effect article discusses the higher mortality of patients admitted for treated to hospitals on the weekend. I don't believe it is relevant to this question about the lower reported weekend deaths.

I thought "everyone knew" this 7-day period fluctuation was due to reduced weekend reporting, but I can't seem to find a good reference for that explanation. Hmph. -- ToE 13:46, 17 July 2020 (UTC)

[4], [5], [6], [7]. --Jayron32 13:50, 17 July 2020 (UTC)

The first three sources aren't particularly useful.

#1, Reduced testing suggested as reason for weekend drop in confirmed COVID-19 deaths, discusses a 50% drop of both single-day deaths and new positive cases in Michigan on one mid-April Sunday compared to the day before, saying "... the Michigan Department of Health and Human Services says the lower daily numbers may be tied to reduced testing over the holiday weekend." That would explain the drop in positives, but not deaths, and no mention is made in the article of delayed reporting.

#2, Why the 'weekend factor' is affecting coronavirus reporting figures in Europe, deals with the Europe, saying, "there seems to be a lag over the weekend as the figures on deaths and hospitalisations work their way through the system, such that reporting on Monday is artificially low, while on Tuesday the figures seem high as they catch up with reality."

#3, Transient Drops In Reported New Coronavirus Cases: ‘Sunday Effect’, does address reporting in the US, but unlike the previous source which at least offers speculation, this one only makes note of the fluctuation without suggesting any cause. "It appears that every Sunday there’s a substantial decrease in numbers of confirmed cases from the previous day or the Friday prior to the weekend. A similar temporary decrease in deaths can be seen every weekend."

But the fourth source is on point, albeit for the UK, not the US.

#4, Understanding the data about COVID-19 related deaths, explains and contrasts DHSC and ONS statistics. The caption for slide #1 states, "The number of registered deaths reduces during weekends (and bank holidays) when deaths tend not to be registered." That is shown graphically in slide #2 which compares "ONS - Deaths by date of registration" with "ONS - Deaths by date of occurrence", showing a steady progression in the latter despite the weekend dips in the former.

I've been unable to find anything like that fourth source but for the US, most likely because "everyone knows" the dips are due to weekend reporting delays and few people feel the need to prove the obvious. -- ToE 15:56, 17 July 2020 (UTC)

Thanks! Staecker (talk) 14:05, 17 July 2020 (UTC)

Popular US news reports sometimes use the phrase "weekend lag", this for example says: "Figures on Monday tend to be lower due to a slowdown in reporting over the weekend". Alansplodge (talk) 12:06, 18 July 2020 (UTC)

Why are there no cute robots which are shaped like plushies?

I can find some designs of them but they're not robots - they can't move on their own. I'm thinking about something like a cat robot that is fluffy and auto hug you. Kazeita (talk) 20:26, 17 July 2020 (UTC)

I don't have any referenced source, but to me it seems immediately obvious that such a toy could (in rare circumstances, while unsupervised) be dangerous to small children/babies, who might get "auto-hugged" in such a way as to injure them, say by putting pressure on an eye. We could use input from an expert on Toy safety regulation. {The poster formerly known as 87,81.230.195} — Preceding unsigned comment added by 90.200.41.197 (talk) 22:03, 17 July 2020 (UTC)

It seems that there are such robots cats and kittens with realistic fur fluffyness. Googling "robot kitten" gives some interesting results like this and this.--109.166.137.83 (talk) 00:30, 18 July 2020 (UTC)

There is also a therapeutic robot seal that will not hug you, but is meant to be hugged.  --Lambiam 08:13, 18 July 2020 (UTC)

See [ www.aliexpress.com/item/32924413933.html ], [ www.aliexpress.com/item/32895794973.html ], [ www.aliexpress.com/item/4000940862423.html ]. --Guy Macon (talk) 08:42, 18 July 2020 (UTC)

NEOWISE comet visibility

For some reason and for several days already I can't see Comet NEOWISE in Warsaw, Poland, coors of observation are 52°16'12.5"N 20°55'51.1"E. I tried to observe at around 23:00 and at midnight, but see nothing except possibly Arcturus and a few major stars and planets. Light pollution or something else? 212.180.235.46 (talk) 22:08, 17 July 2020 (UTC)

If you're actually in Warsaw, or any other major city, then light pollution will not permit you to see the comet. You will need the sky to be dark enough at least to be able to see the Big Dipper, near where the comet is currently situated, and whose stars are roughly the same apparent magnitude as the comet.--Shantavira|^{feed me} 09:55, 18 July 2020 (UTC)

• Neowise is expected to return in a few thousand years. It is possible that the people who have left Poland (or Europe, or even the planet) by then have turned off the lights prior to their extinction / diaspora.
• It should be easily visible in a few millennia for those of us who spend their post-senescent retirement on a depopulated solar satellite. --Cookatoo.ergo.ZooM (talk) 16:12, 18 July 2020 (UTC)

The OP may, like myself in the UK, have been too far north to see the comet easily when it was a morning object, because in more northerly latitudes (compared to, say, the US) the summer Sun does not get as far below the horizon, so the twilight remains brighter.

The comet is now an evening object, and is moving night-by-night more perpendicularly away from the horizon, contrasted to its nearly horizontal movement when it was a morning object (see the diagrams in this Sky & Telescope article), so the OP (and I) can hope for better luck in the next week (cloud cover permitting). {The poster formerly known as 87.81.230.195} 90.200.41.197 (talk) 21:01, 18 July 2020 (UTC)

July 18

Long-range dispersal of stromatoliths

I have a question about the bacteria that form living stromatolites. Is there any research out there about how these bacteria disperse and end up in places like Pavilion Lake and Lake Untersee? I have looked for such and didn't find anything. Jo-Jo Eumerus (talk) 20:44, 18 July 2020 (UTC)

It seems that these bacteria are no specific 'stromatolite bacteria', but that many different bacteria and algae and varied associations of these can build stromatolites given some suitable conditions. And possibly these same bacteria and algae are found everywhere on Earth but usually they just don't build stromatolites. So the question becomes how does any bacterium reach some specific location on Earth? Surely carried by water: [[8]] "Water is one of the most important bacterial habitats on Earth. As such, water represents also a major way of dissemination of bacteria ...". And wind would disperse bacterial spores over huge distances given that they can stay alive over centuries and even millennia, see e.g. endospore. 2003:F5:6F0F:6500:38C7:928B:9AB4:495F (talk) 23:22, 18 July 2020 (UTC) Marco PB

Soaring owls

Are there any owls that ridge soar - in particular over UK moorland? catslash (talk) 22:06, 18 July 2020 (UTC)

Owls are thought usually not to soar and actually they hunt by flying low and locate their prey using rather their ears than their eyes. But they are apparently able to soar occasionally, as for example reported here: [[9]]. Did you observe a soaring bird that you think could have been an owl? I suppose that an owl will soar sometimes maybe to fly back home, or will take advantage of a bright full moon night and open landscape to hunt by sight. 2003:F5:6F0F:6500:38C7:928B:9AB4:495F (talk) 22:55, 18 July 2020 (UTC) Marco PB

I did observe a large bird that seemed to have forward-looking eyes, soaring low over a small ridge a little above the highest field (~1600 ft) before the sun set on a west-facing slope. It drifted about, never flapping, loitering in my vicinity before drifting off along the ridge. It was pale and had a small tapering (as opposed to fan-shaped) tail. I had no camera. catslash (talk) 23:33, 18 July 2020 (UTC)

July 19

Astronomy question

Can there be you see both Venus and Mars together in the same sky? How often does that happen? Preferably in the same direction. 166.137.83.31 (talk) 10:05, 19 July 2020 (UTC).

See Conjunction (astronomy). The external links include a site that will allow you to look up future conjunctions. If you know your astronomy, you might even be able to work out where those will be visible from, based on the provided celestial coordinates. Someguy1221 (talk) 12:27, 19 July 2020 (UTC)