Wikipedia:Reference desk/Archives/Science/2022 February 5

= February 5 =

Chickens
How does chickens don’t move head when moved?

https :// youtu. be/ yetr1YDZwz8

--37.116.102.74 (talk) 09:55, 5 February 2022 (UTC)
 * This link works: https://www.youtube.com/watch?v=yetr1YDZwz8 . The domesticated chicken is a Flightless bird that has inherited the 3-axis head stabilisation ability of its flying ancestors. Philvoids (talk) 11:54, 5 February 2022 (UTC)
 * According to https://sorrychicken.com/chickens-fly, even domesticated chickens can fly, albeit neither high nor far. -- SGBailey (talk) 19:36, 9 February 2022 (UTC)
 * Chicken notes "Domestic chickens are not capable of long-distance flight, although lighter chickens are generally capable of flying for short distances, such as over fences or into trees (where they would naturally roost). Chickens may occasionally fly briefly to explore their surroundings, but generally do so only to flee perceived danger." There's a lot of qualifications on "flight", but they are capable of short flights.  They certainly can't take to the skies, but they can jump and flap to cover short distances.  -- Jayron 32 19:57, 9 February 2022 (UTC)
 * More so than turkeys? --←Baseball Bugs What's up, Doc? carrots→ 21:25, 9 February 2022 (UTC)
 * As God is my witness... -- Jayron 32 13:09, 10 February 2022 (UTC)

The ins and outs
The i of 1 December 2021 notes that on this day in 1997 "Kenny G set a world record when he held a note on his saxophone for 45 minutes and 47 seconds.  The record has since been broken by Geovanny Escalante, who held a note for 1 hour, 30 minutes and 45 seconds, using a technique that allows him to blow and breathe at the same time." What is this technique? 86.175.202.208 (talk) 17:28, 5 February 2022 (UTC)
 * Circular breathing. Fgf10 (talk) 18:06, 5 February 2022 (UTC)
 * The previous record, of course, would also have had to involve this method. --184.144.97.125 (talk) 08:09, 6 February 2022 (UTC)

Catastrophic impact of asteroid on Earth
What difference does it make if an asteroid with a diameter of some km hits the Earth in the middle of the ocean? If we shoot at it with anti-aircraft artillery and break it up in smaller pieces? --Bumptump (talk) 19:37, 5 February 2022 (UTC)
 * Unless these pieces are small enough to evaporate in the atmosphere, the kinetic energy of the impact remains the same. Current anti-aircraft artillery will only make relatively small pits in a kilometres-deep rock. The highest altitude reached by artillery is Project HARP's world record of 180 km; if the asteroid is approaching with a speed of 94,000 km per hour, that gives us a window of grace of less than seven seconds in which to shoot it to smithereens. --Lambiam 00:40, 6 February 2022 (UTC)
 * Coincidentally (I assume), yesterday's issue of New Scientist magazine has an article on p10 ('We could save Earth from a planet-killer comet (if leaders listen to scientists)' by Jonathan O'Callaghan) reporting a recent study on precisely this topic, which can be found at . The study was of course inspired by the recent film Don't Look Up.
 * The short take is that it would be possible to fragment a 10km-diameter comet or asteroid sufficiently if we were able to launch 1000 specially designed, precisely targeted and coordinated nuclear missiles 5 months before impact to reach the target 1 month before, although a few smaller fragments would likely still impact Earth and cause less-than-global damage and deaths. By implication, later and/or less than that would be insufficient.
 * As has been extensively discussed elsewhere, it would be much easier to prevent the object from impacting at all if it were deflected many months or several years earlier, but the study assumed the same scenario as the movie with the impactor only being spotted 6 months out (giving us 1 month to get our ordinance together). {The poster formerly known as 87.81.230.195} 90.209.123.164 (talk) 01:55, 6 February 2022 (UTC)

Responses so far have been concerned with the feasibility of breaking up the asteroid, but that's only part of the question. Someone must have worked out the damage from an oceanic strike by different sizes of impactor; so, supposing that we could break up this hypothetical asteroid, what difference would it make? --184.144.97.125 (talk)


 * As Prof. Jay Melosh explains here, in an ordinary impact, ejecta reentering the Earth's atmosphere will heat up and emit thermal radiation. This will cause the surface temperature to rise to hundreds of C and thereby cause the most severe immediate problems for the Earth's ecosystem. The total energy radiated to the Earth's surface is then equal to the kinetic energy of the ejecta, whcih is a fraction of the total kinetic energy of the original impactor. So, if we were to totally fragment a large asteroid and all pf the fragments would burn up in the atmosphere, then all of the kinetic energy of the impactor would end up in the atmosphere, making the most severe immediate effect of the impact much worse. Count Iblis (talk) 08:40, 6 February 2022 (UTC)


 * For a previous example, see Eltanin impact "...approximately 2.51 ± 0.07  million years ago... The asteroid was estimated to be about one to four km (0.6 to 2.5 mi) in diameter. No crater associated with the impact has been discovered. The impact likely evaporated 150 km3 (36 cu mi) of water, generating large tsunami waves hundreds of metres high". Alansplodge (talk) 10:22, 6 February 2022 (UTC)
 * See also If an Asteroid Hits the Ocean, Does It Make a Tsunami? (Probably Not). Alansplodge (talk) 10:26, 6 February 2022 (UTC)


 * A single large impact will create a different tsunami than multiple smaller simultaneous impacts a few hundred kilometres apart. With smaller fragments, there will be more waves, but less high and therefore more survivable. Ejecta radiating the energy back to the surface have been mentioned, but if fragments are small enough that they don't reach the surface, there won't be ejecta, so no efficient way to radiate the heat to the surface. Instead, the mesosphere (and for somewhat larger fragments stratosphere) will be heated, but heating on the surface will be limited. A 1 kilometre comet provides on the order of 1020J of kinetic energy. Spread over about 1015kg of air in the mesosphere, that will heat the air by a hectokelvin. Somewhat larger impacts that blow ejecta into the stratosphere can cause a regional heating problem, but not global. Shockwaves reaching the surface from the stratosphere may be the main immediate problem. The main problem on a longer term is global cooling, but if we can arrange that individual impacts are small enough that ejecta stay mostly in the troposphere, is won't take too long before the dust has settled. So, breaking the impactor up before impact helps in some ways, even if the total energy stays the same. PiusImpavidus (talk) 12:07, 6 February 2022 (UTC)


 * This reminds me of the ridiculous scene in Independence Day where American fighter aircraft were trying to bring down a gigantic alien ship with puny air-to-air missiles. Clarityfiend (talk) 17:04, 6 February 2022 (UTC)
 * Like the puny artillery shell that sank the HMS Hood? --184.144.97.125 (talk) 06:07, 7 February 2022 (UTC)
 * Well, I'll admit it did take only one ramming to blow it up completely. Must have been designed by the same people who developed the Death Star. Clarityfiend (talk) 10:24, 7 February 2022 (UTC)
 * Aliens have been brought down by much punier weapons. Mitch Ames (talk) 01:24, 8 February 2022 (UTC)
 * The strategy in that movie was terrible. And the Death Star should've compartmentalized that trench with laser grids or force fields or brick walls or something. Sagittarian Milky Way (talk) 22:09, 7 February 2022 (UTC)
 * But we were shown in Rogue One that Galen Erso, coerced into working on the Death Star's design, secretly incorporated the weak spot, and in Star Wars that its crew didn't realise it was there until the attack was already in progress. {The poster formerly known as 87.81.230.195} 90.208.90.238 (talk) 16:31, 8 February 2022 (UTC)