Subject: Can someone please explain?
Posted by: Mixamatosis
Date: Jan 21 17
I've read that it's dangerous to mix ammonia and bleach. Variously I've read that it can produce deadly cyanide gas, chlorine gas (which is said to be bad for you) and even explosions.
However swimming pools are kept fit for use with chlorine, and our urine contains ammonia but then we may clean toilets with bleach. Also many cleaning products contain either ammonia or bleach and it would be easy to use them unthinkingly in combination.
How is it that people aren't generally harmed by these dangers when swimming in swimming pools or doing daily cleaning, or are we being harmed at low level and is the harm cumulative?
Posted by: Mixamatosis
Date: Jan 21 17
I've read that it's dangerous to mix ammonia and bleach. Variously I've read that it can produce deadly cyanide gas, chlorine gas (which is said to be bad for you) and even explosions.
However swimming pools are kept fit for use with chlorine, and our urine contains ammonia but then we may clean toilets with bleach. Also many cleaning products contain either ammonia or bleach and it would be easy to use them unthinkingly in combination.
How is it that people aren't generally harmed by these dangers when swimming in swimming pools or doing daily cleaning, or are we being harmed at low level and is the harm cumulative?
526 replies. On page 20 of 27 pages. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
brm50diboll 
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Fire is a source of light. Opaque objects (things that block light, not emit it) produce shadows. People who stand around a campfire at night produce shadows. The shadows are of the people (which block the light), not of the fire (which produces the light), although the shadows wouldn't be there if it weren't for the fire. Reply #381. Oct 20 18, 4:33 PM |
| brm50diboll
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Looking for shadows caused by a source of light is about as ridiculous as looking for the dark side of the sun. The sun does rotate, but it has no night side because it is a *source* of light. Reply #382. Oct 20 18, 4:35 PM |
LoveAnimals555
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I agree....I am still trying to think! Reply #383. Oct 22 18, 8:20 PM |
| brm50diboll
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OK. On to Neptune. Neptune was discovered as a consequence of mathematical analysis. The orbit of Uranus was a bit unusual, not seeming to follow Newton's laws precisely. It had been speculated that *if* there were a reasonably sized planet beyond Uranus, its gravity might have the effect of perturbing Uranus's orbit as observed. So the hunt was on for such a planet, and in 1846 Neptune was discovered. Neptune is similar in many ways to Uranus, slightly smaller but actually slightly more massive than Uranus, due to being a bit denser than Uranus. Neptune has a blue color due to the presence of small amounts of methane in its atmosphere. Like the other outer Jovian planets, Neptune has rings and several moons. Studies of Neptune's orbital dynamics indicates it originally formed much closer to the Sun than where it now is, but gradually spiralled outwards due to gravitational interactions with the other Jovian planets over billions of years. Neptune has been visited only once by a space probe. Like Uranus, it was visited in a "fly by" by Voyager 2. Voyager 2 had passed Uranus in 1986, and passed Neptune in 1989. Neptune has only recently completed one orbit of the Sun since it was originally discovered. Reply #384. Nov 18 18, 1:44 PM |
Mixamatosis
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Only one orbit of the Sun since 1846. That's a long winter and summer. Reply #385. Nov 19 18, 11:56 AM |
| brm50diboll
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Neptune's largest moon is Triton. It is believed that Triton is not an original moon of Neptune, but a captured moon. There are several pieces of evidence for this, but the one I want to elaborate on is that the orbit of Triton around Neptune is retrograde. What does retrograde mean in astronomy? The vast majority of celestial objects in our solar system, including such small objects as asteroids, comets, and moons, both rotate (spin on their own axes) and revolve (orbit around the parent body, be it the Sun itself or a planet) in a prograde fashion. That is, if you were observing the solar system from a point high above the North Pole of the Sun (yes, the Sun *does* have a North Pole, since the Sun rotates), then the rotation and revolution of the vast majority of the bodies "below you" would appear to be in a counterclockwise fashion. (If viewed from far below the Sun's South Pole, all these rotations and revolutions would appear to be clockwise.) Why is that? Because of a Law in Physics called the Law of Conservation of Angular Momentum. In the original nebula that our solar system formed from over 4.5 billion years ago, the nebula itself rotated in a prograde fashion. Since the bodies in our solar system all derive from that original nebula, the Law of Conservation of Angular Momentum predicts that the vast majority of those bodies would have retained their original prograde rotation and revolution. The Sun today rotates in a prograde fashion. The only way retrograde rotation or revolution could have occurred would be in a collision that was way, way, off center between the centers of masses between the colliding bodies. So anytime we see retrograde motion in any body in today's solar system, some such catastrophic collision must have occurred at some point in the past. Venus looks awfully bland today. But Venus's rotation is retrograde. Viewed from above the Sun's North Pole (or Venus's North Pole), Venus appears to spin clockwise, not counterclockwise like the Sun or the Earth or most of the other planets, asteroids, moons, and comets. If you could somehow survive being on Venus, there the Sun would rise in the west and set in the east. Similarly, the orbit of Triton around Neptune is retrograde. As viewed from a point high above Neptune's North Pole, Triton would appear to be orbiting clockwise around Neptune, while the other major moons of Neptune would be orbiting counterclockwise around Neptune. Neptune itself both rotates and revolves around the Sun in a prograde (counterclockwise as viewed from above the North Poles) fashion. This retrograde orbit of Triton, by itself, tells us Triton suffered a cataclysmic collision at some point in its past. In fact, that collision was most probably what resulted in Triton being captured into orbit around Neptune. Prior to that captured, Triton was very similar to Pluto, orbiting the Sun independently in an eccentric, highly inclined orbit. It most likely struck a long-gone original moon of Neptune at a very strange angle, leading to its capture. One more interesting consequence of the Law of Conservation of Angular Momentum: bodies which revolve in prograde orbits tend to slowly spiral outwards from their parent bodies over billions of years. We know, for example, that our Moon is slowly getting farther and farther away from us, about 2 cm per year, actually according to NASA laser reflection experiments set up during the Apollo moon landings (if I may digress, yet another piece of evidence even today that the moon landings were real, not faked.) But objects in rare retrograde orbits tend to spiral slowly inward towards their parent bodies over billions of years. Triton is very slowly spiralling inwards towards Neptune. In billions of years, it will crash into Neptune. Reply #386. Dec 15 18, 2:06 PM |
| brm50diboll
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Beyond Neptune is a vast region called the Kuiper belt, after the Dutch astronomer Gerard Peter Kuiper, who described it. The Kuiper belt is one of two areas in the solar system from which comets originate. The other region, the Oort cloud, is much, much farther away than even the Kuiper belt. There are probably many millions of small bodies in the Kuiper belt, a few thousand of which have presently been discovered. But the most famous body in the Kuiper belt is Pluto, discovered by Clyde Tombaugh in 1930. Pluto was originally considered to be a planet. It was downgraded to "dwarf planet" in 2006. At another time, I will discuss why that happened. It's too complex a subject for me to want to get into at this time today. Reply #387. Jan 03 19, 11:45 AM |
| Mixamatosis
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I seem to recall seeing some object photographed in the Kuiper Belt just recently by a probe which has gone farther than any other so far. The object was 2 spherical objects joined and was nicknamed 'The Snowman'. Reply #388. Jan 06 19, 3:50 PM |
| brm50diboll
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The New Horizons mission which flew by Pluto a few years ago has just passed another Kuiper belt object a few days ago. The object was called Ultima Thule. New Horizons is so far away from Earth now it takes several hours for its transmissions to reach us. Reply #389. Jan 06 19, 9:37 PM |
| brm50diboll
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OK, to the issue of why Pluto is no longer considered a planet: I'm sorry, but I agree with the IAU (International Astronomical Union) in their decision to "relegate" Pluto in 2006. Sorry, Pluto fans, but it was necessary to prevent what would be utter chaos if that decision hadn't been made, as it was a direct consequence of new information, which is the very nature of science itself. Science is *not* dogma. It is not static, it is refined with new information. Let's talk about the fundamental issue here, which is the definition of what a planet is. So, to the ancients, a planet (which literally translates as "wanderer") was a star that wandered (that is, a star that did not keep its place in a constellation, but wandered from constellation to constellation.) And to the ancients, a star was a point of light visible at night. The ancients did not have telescopes, so stars and planets were not huge spheres or worlds. They were points of light seen at night. That is all. No one knew what they really were, so all kinds of myths were created about them. To the ancients, there were only five planets: Mercury, Venus, Mars, Jupiter, and Saturn. Every one of those five were stars (points of light in the night sky, not spheres or worlds) that moved from constellation to constellation. Note that Earth was *not* a planet to the ancients. Obviously! Earth was not a point of light in the night sky and Earth didn't move. When the European Renaissance came, and it became common knowledge the Earth was spheroid and then Copernican heliocentric theory was accepted by at least the educated class (if not by the Church), then Earth was added to the list of planets, as telescopes had recently revealed that the five previously known planets were spherical in nature, like the Sun and the Moon. So a new definition of planet was created with this new information: a planet was a body (typically almost spherical, or spheroid) that orbited the Sun. Note that the new definition included the five planets under the old definition, and added Earth, but excluded the Sun and the Moon, as the Sun does not orbit the Sun, and the Moon was known to orbit Earth, not the Sun. What about comets, you may ask? Comets orbit the Sun. Yes, but despite the recent invention of the telescope, Renaissance astronomers considered these objects with long tails different enough from planets to be excluded from being considered planets, even though they were certainly known at that time. And when Galileo discovered Ganymede, Callisto, Europa, and Io, he did not consider them planets either, but correctly classified them as moons of Jupiter, since they orbited Jupiter, not the Sun. And so the six planets remained until 1786, when William Herschel discovered Uranus. This discovery, like most discoveries, created both opportunities and problems for astronomers. Clearly, Uranus was a planet because it was a large spheroid body (as viewed with a telescope) that orbited the Sun. But without the telescope, it would not have been discovered (or at least its true planetary nature would not have been recognized.) But this meant that more planets may be discovered as telescope technology improved, in fact, the problem was: Who knew how many undiscovered planets future telescopes might discover? Maybe hundreds or thousands. Too many for school children to memorize, that's for sure. Then came 1801 (Yes, 1801, not 1846). In 1801, Ceres was discovered. Ceres was a small dot in a telescope, not a "point of light". Ceres orbited the Sun. Therefore, by the existing definition of a planet in 1801, Ceres was a newly discovered planet. It was even given its own astronomical planetary mythological symbol, like the other planets. Within a few years, three more such planets were discovered: Pallas, Juno, and Vesta. But Ceres and the other three new "planets" created a problem for astronomers: they were not spaced far away from each other like the other previously discovered planets, but all four were in a narrow region between Mars and Jupiter and worse, some of their orbits *overlapped*. Also, these four bodies were not large enough to show up as spheroid in the telescopes of the time. They were obviously solid bodies, not stars, but much smaller than the other known planets, so when the fifth such body was discovered between Mars and Jupiter, astronomers made the hard call and "downgraded" all of them to a new category they created: asteroid or minor planet. Yes, minor planet is an official astronomical term for asteroid that has existed since the 1800s. Minor planets (asteroids) are given numbers as well as names when they are discovered (in order of their official acceptance as being discovered), so Ceres was rechristened as 1 Ceres (the first asteroid.) My point is, downgrading "planets" with new information happened long before 2006. There are well over 100,000 numbered minor planets (asteroids) today, with probably millions more to come over time, so it's a good thing for elementary school kids everywhere these asteroids aren't considered planets anymore. Yes, Little Johnny, tell us planet #43,278. Probably wouldn't improve science education if that were the case. When Neptune was discovered in 1846, it was clearly a new planet, not as asteroid. It was obviously bigger than Earth and it was further away than the other known planets, so it was nowhere near the "asteroid belt" between Mars and Jupiter. Yes, Neptune really was a genuine planet, not a "poser", as Ceres had been. Astronomers continued to discover new asteroids after 1846 into the early 20th century, and while doing so, a new problem was identified: while most of these new minor planets (asteroids) were in the "asteroid belt" between Mars and Jupiter, a few asteroids were discovered that *weren't* in the belt. So what would happen if an asteroid were found really out of place? Now we arrive at Clyde Tombaugh's discovery of Pluto at the Lowell Observatory in Arizona in 1930. Just as Neptune had been discovered by analyzing small deviations in Uranus's orbit that led to a hypothesis a planet beyond Uranus existed, so astronomers, including Percival Lowell himself, believed there were irregularities in Neptune's orbit that could only be explained by the existence of yet another planet even further off, so the hunt for this planet was on. Problem was, Lowell and the others were wrong about the mathematics of Neptune's orbit, but they didn't know that. So after Lowell died, when young Clyde Tombaugh found a tiny dot that "moved" on a photographic plate, the controversy erupted over just what it was Tombaugh had found. It was very dim, so the first thought was that it was an asteroid. But calculations showed it was farther from the Sun than Neptune. Given the ongoing search for the source of Neptune's orbital "discrepancies" (as they then thought existed), their rough calculations at the time showed that Pluto was in approximately the right place for the "perturbation" and was larger than Earth (man, they were *way* off on that one, as we know now that Pluto is smaller than our Moon, now). Hallelujah! Another triumph of astronomical mathematics! Just as we'd found planet Neptune by analyzing small deviations in Uranus's orbit, now we've found planet Pluto by analyzing small deviations in Neptune's orbit. Except that wasn't really what happened. As the years went by after 1930, many troubling things kept showing up about Pluto. As telescopes improved, better estimates of Pluto's true size kept being made, and they were always *smaller*. First Pluto is bigger than Earth. Then, no, it's smaller than Earth but still bigger than Mercury (a known planet.) Then, no, it's smaller than Mercury but bigger than the Moon. Then, no, it's smaller than the Moon but bigger than Ceres, the largest asteroid. That's where we eventually wound up. By that time, generations of school kids had been taught Pluto was the ninth planet. But there were other problems: Pluto's orbit is far more elliptical than any other planet's. It's orbit is also further off the plane of the ecliptic than any other planet's. In fact, Pluto's orbit even crosses "inside" of Neptune's orbit, so that for the 20 years from 1979-1999, Pluto was actually closer to the Sun than Neptune. These were all very strange things for a planet. (Pluto will never collide with Neptune, though. There is a 3:2 orbital resonance between Pluto and Neptune so that whenever one of them is at one of the "intersection points", the other is always far away.) Then Gerard Kuiper came along with his hypothesis that one source of short period comets was a "Kuiper belt" beyond Neptune full of many thousands of icy bodies. By the late 20th century, most astronomers believed Pluto was such a Kuiper belt body, the first one discovered, in fact. Other Kuiper belt bodies were discovered, but, fortunately for the defenders of Pluto's status as a planet, these other bodies were smaller than Pluto. Now finally comes 2006. Mark Brown discovered a Kuiper belt object he initially calls "Xena" (after the campy TV show heroine) that he feels is larger than Pluto. So if Pluto is Planet 9, then "Xena" must be Planet 10. And so the debate went to the IAU. Stop the insanity! Stop it! Just stop it! The IAU knew what a disaster it would be to recognize "Xena" (now officially and appropriately named Eris, after the goddess of discord who started the Trojan War with her golden apple marked "To the Fairest") as a planet. There were many thousands of Pluto-sized bodies in the Kuiper belt waiting to be discovered by advanced telescope technology. No way school kids could be expected to know all that. It would be just like the 1800s again. Once again, what was needed was a more precise new definition of what a planet was. The key part of the new definition of planet is that a planet must "clear its orbit" of similarly-sized bodies. If the body in question was spheroidal but did not clear its orbit, it was placed in a new category called "dwarf planet". Since the Kuiper belt objects did not clear their orbits, we no longer had to worry about thousands of "planets" out there some day being discovered. Problem solved. Eris was declared a dwarf planet, along with a few others (Sedna is one I remember off the top of my head). Of course, the downside was Pluto was "relegated" to dwarf planet and Ceres, the only asteroid large enough to be spheroidal, was changed yet again, this time "promoted" to dwarf planet. (Its big sister asteroids Pallas, Juno, and Vesta did not "make the cut" and remained minor planets or asteroids. The categories are not mutually exclusive, though, so Ceres is both an asteroid and a dwarf planet. It is the smallest known dwarf planet, though, as the other ones so designated thus far in the Kuiper belt are all larger than Ceres.) All this was necessary to prevent chaos in planetary terminology. It was not new to astronomy. A similar thing had happened before in the 1800s. This is what science does when it must incorporate new data into its theory that does not "quite fit". It happens in all branches of science, not just astronomy. It is part of the scientific method itself. Sorry, Pluto fans. Pluto is not, and honestly, should never have been in the first place, a planet. Reply #390. Jan 17 19, 3:38 PM |
| brm50diboll
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A few corrections: the name of the astronomer that discovered Eris is Mike Brown, not Mark Brown. I had a few problems with the distinction between its (the possessive pronoun) and it's (the contraction for it is) though most of the time I did get it right. Not too many typos for such a long post. Reply #391. Jan 17 19, 5:27 PM |
| brm50diboll
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As we reach the outer limits of our solar system, it is time to talk about comets. Comets have been known since ancient times, but they were not considered astronomical phenomena until fairly recently. Comets were considered dire omens from the gods (or some such), or atmospheric phenomena. While today people think of comets as periodic; in fact, most comets have periods so much longer than a human lifespan that their periodic nature would be completely hidden without modern advanced technology. Comets were, for most of human history, a random, unpredictable event. So what are comets? They are remnants of the early outer solar system that never became incorporated into planets or moons. The ones have "long periods" of tens of thousands of years have changed very little from their origins 4.5 billion years ago. Because they spend the majority of their time in the cold outer solar system, they contain a lot of water ice and other volatile materials that would (and in fact does) turn into gases if the comet ever enters the inner solar system. Most bodies that could be comets aren't because they never enter the inner solar system. Those that do became comets when some massive body (perhaps a rogue planet or a nearby star that wandered too close to our solar system millions of years ago), disturbed their orbits and caused some of them to enter highly eccentric elliptical orbits that brought them temporarily into the inner solar system where their volatile components partially vaporized, forming the characteristic tail of the comet. Even so, most comets spend most of their time far away from the Sun, where they are invisible to all but the most powerful modern telescopes. This is a consequence of Kepler's Laws of planetary motion (which also applies to comets) which says that bodies speed up as they move closer to the Sun and slow down as they move farther away. So, in an orbit that may take over 10,000 years, a long-period comet will spend less than a year of that time in the inner solar system. Comets can be divided roughly into two broad categories: long-period comets, with periods of thousands of years, and short-period comets, with periods of a few centuries or less. The short-period comets mostly originate from the Kuiper Belt, just beyond Neptune's orbit. If Pluto's orbit were somehow disturbed and put it on a path into the inner solar system, Pluto would be by far the brightest comet ever seen in human history. Of course that can't happen, but basically Pluto is made of the stuff comets are made of, just a lot more of it. The Kuiper Belt is (very roughly) within a few degrees of the plane of the ecliptic, which the planets orbit in. But the long-period comets originate much further away than the Kuiper belt, in the Oort cloud, which extends from 100 or so AU (astronomical units - the distance from Earth to the Sun) all the way out to the gravitational edge of the solar system, about one full light year away. These outer comets are not generally close to the ecliptic, but spherical in distribution, so they can come to us from any angle in the sky. It is believed that the short-period Kuiper belt comets were once long-period Oort cloud comets that had their periods shortened drastically and became trapped in the Kuiper Belt when, on one of their rare passes into the inner solar system, they passed too close to Jupiter or Saturn. A few comets got trapped in even closer orbits, where they eventually lost all their volatile components and became "extinct comets" and contributed to meteor showers. And fewer still actually crashed into planets. The collision of Comet Shoemaker-Levy 9 with Jupiter in July of 1994 is one of the most spectacular recent reminders of what can (and occasionally does) happen in our solar system. A collision like that with Earth would be a mass extinction event. Since Earth is much less massive than Jupiter, such collisions are spectacularly rare, but they have happened in Earth's geologic history, typically on the order of once every 100-200 million years over the last billion years or so. And unlike the similar asteroid collisions (like the K-T impact that contributed to the extinction of the dinosaurs 65 million years ago), a cometary collision could not be anticipated years ahead of time, as Oort cloud comets are mostly undiscovered until they are already a year or two before they enter the inner solar system, by that time far too late for anyone to do anything about it except wait for the inevitable collision. I digress here, but, in my opinion Deep Impact was a much better movie than Armageddon (although both had serious scientific deficiencies.) Reply #392. Feb 16 19, 4:49 PM |
| brm50diboll
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I haven't used this hokey convention in awhile, but I feel this is a good time for it, so here goes: Brian, what are grand unified theories (GUTs)? Grand unified theories (there are several of them) are theories in physics that attempt to unify all the known laws of physics under one consistent mathematical framework. These have (in various incarnations) been the "Holy Grail" of modern theoretical physics since the early 20th century now. Einstein himself labored fruitlessly the last 20 years of his life on a GUT that would marry his General Theory of Relativity with quantum theory. To date, the success of various GUTs has been partial at best. The basic problem is that Relativity and Quantum Theory (looking at the problem one way) are mathematically incompatible and both break down under conditions which favor the application of the other. More specifically, Relativity is favored under conditions of the very large (velocities approaching the speed of light, huge masses of black holes, enormous distances in space, etc.), while quantum theory is favored under conditions of the very small (atoms, subatomic particles, even "strings" and "branes".) Einstein wanted a quantum theory of gravity, but failed to get it. Heisenberg's darned Uncertainty Principle kept getting in the way. But the problem can also be looked at another way (and theoretical physicists love arguing among themselves which is the best way to frame the problem.) In this perspective, the GUTs attempt to merge mathematically the mathematics behind the four fundamental forces in nature and their carrier particles (bosons). Those four fundamental forces are: electromagnetism (electricity and magnetism having been successfully merged by James Clerk Maxwell in the 19th century), the strong nuclear force, the weak nuclear force, and gravity. In the mid 20th century, a limited GUT successfully married together electromagnetism, the strong nuclear force, and the weak nuclear force (and each of their carrier particles), a theory known now as the Standard Model. The Standard Model is a quantum theory. But gravity (and its carrier particle the graviton) resisted incorporation into the Standard Model because gravity is a relativity-based theory, not a quantum theory. But gravitons, like all particles, are quantum in nature, so if a mathematically consistent theory for how gravitons should behave could be developed and experimentally verified, then the "Holy Grail" of physics will be found. So we have built massive superconducting particle accelerators like the Large Hadron Collider with CERN looking for "The God Particle" (formally known as the Higgs boson), and we believe we have found that elusive particle. We believe. I, myself am not competent to judge that. I believe the Higgs particle itself has been found but I am not competent enough to understand how that ties in with gravity and the graviton, although apparently it does if you understand string or brane theories, which I really don't. Apparently the proponents of these theories argue with themselves over which is the best explanation for the experimentally determined results. Gee Brian, sounds like a lot of mumbo jumbo to me. Yeah, I know. But I really do think the "Sheldon Coopers" out there *almost* have it. So now you know what grand unified theories (GUTs) are, or at least can pretend to. Remember, if you can't dazzle them with brilliance, baffle them with BS. Reply #393. Mar 19 19, 6:36 PM |
| Mixamatosis
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I was looking at an image of Jupiter's storms and a question occurred to me. These storms seem to be permanent. They don't seem to blow out or blow over like storms on Earth, unless I am misunderstanding something. Why is that? Reply #394. Mar 22 19, 1:10 PM |
| brm50diboll
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Several reasons. First, there is no solid surface to break up storms as on Earth. As you know, hurricanes die fairly quickly when they hit land, especially mountains. Second, it is not strictly true that the storms *never* die. Although the Great Red Spot has been a well-known feature of Jupiter by telescope since the 17th century, smaller storms on Jupiter have come and gone. Third, at cloud level in Jupiter's atmosphere, which is what our optical telescopes see, it is much, much colder than Earth's atmosphere (yes, deep down in Jupiter it is very hot, but what we see is in a very cold outer layer). Cold gases are more resistant to changes due to turbulence than hot gases. Consequently, storms would last much longer on cold Jupiter than warm Earth. Fourth, the Great Red Spot isn't really analogous to a hurricane on Earth anyway. Hurricanes are low-pressure features. But the Great Red Spot is a *high* pressure feature. The Great Red Spot is more analogous to a mantle plume beneath a geologic hot spot like the Kilauea volcano on the big island of Hawaii than it is to a hurricane. The source of the rising plume of gases that creates the Great Red Spot is likely deep within Jupiter, in the hot, dense layers of the planet's gases. That source, whatever it is, is long-lasting, like the mantle plume beneath Kilauea. And a few other things. Reply #395. Mar 22 19, 9:02 PM |
| Mixamatosis
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Thank you Brian, the depth of your knowledge on this subject is impressive. Reply #396. Mar 23 19, 2:07 AM |
| Mixamatosis
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I watched a fascinating programme today - one by Brian Cox, all about the life cycle of stars and how the elements that exist in the Universe are created in the dying stages of stars, including carbon which is a part of all life forms. Also the Betelgeuse, a star in Orion's Belt, 600 light years away from our solar system, is in its dying stages and could become a supernova anytime between now and the next million years. (It could have happened already since it takes 600 years for light from Betelgeuse to reach us). Reply #397. Apr 06 19, 12:00 PM |
| brm50diboll
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Carl Sagan made the same point in Cosmos back in the 70s. We are all starstuff. Actually, hydrogen, helium, and a trace of lithium were *not* made in stars but were original products of the big bang itself. While elements like carbon and oxygen are generated in red giants and supergiants (Betelgeuse is the closest red supergiant to Earth), elements heavier than iron can be made only in supernova explosions. If Betelgeuse were to go supernova in the near future (I've discussed this issue before; the probability that Betelgeuse has already gone supernova is practically nil, current best estimates are in the neighborhood of 100,000 years) it would *not* threaten life on Earth (I hate these overblown cosmic panic stories). However, at its peak brightness it *would* be brighter than a full moon (though still just a point in the sky) and it would be visible in broad daylight for several weeks. Reply #398. Apr 07 19, 6:36 PM |
| Mixamatosis
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Brian. What you said doesn't contradict what Brian Cox said. I just simplified things in my post, but when you simplify things you always risk losing some accuracy. I did know, because he did say, that Hydrogen and Helium were in stars already (post big bang) and not created by the dying process, though the effects of the dying process on them mean they are involved in creating other elements. Reply #399. Apr 08 19, 2:18 AM |
| Mixamatosis
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That's what I understood anyway, but again I am putting it in my own words. Reply #400. Apr 08 19, 2:18 AM |
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