Posted on November 26th, 2010 No comments
One last Thanksgiving-related question, since Friday is still a holiday for some of us.
There are two correct answers to this, but only one was mentioned by Twitter correspondents. The first correct answer was from @little_mavis: The guinea pig is a species domesticated in the New World but given an Old World name.
Guinea pigs (Cavia porcellus) are called “pigs” (commonly and scientifically) because of their pig-like build and the pig-like sounds they make. They were first domesticated in mountainous regions of northwestern South America. Why they are called “guinea” pigs is a matter of conjecture, and may be a combination of several factors. One hypothesis is that “guinea” is a corruption of Guiana, though they’re not originally from there, either. Another guess is that “guinea” pigs may have been imported to Europe via Guinea (West Africa) and so been named for the wrong place.
The misnaming of the “guinea” pig may simply be similar to the misnaming of the turkey. It may have been intentionally named for an exotic-sounding place, even though that place is not where the animal actually came from.
A third species first domesticated in the New World and given a misplaced name is the muscovy duck (Cairina moschata). It’s not from Muscovy, but from northern South America and possibly Central America.
The muscovy duck is the only breed of domestic duck not descended from the mallard (Anas platyrhynchos). Most domestic ducks are descended entirely from the mallard, but a few from hybrids of mallard and other Anas species. In fact, transgeneric hybrids of muscovy ducks and mallard-derived ducks can be bred, but the hybrids can not reproduce. They are often raised for meat because they grow quickly, like mallard-descended domestic ducks, but grow to be larger, like the slower-growing muscovy duck.
The muscovy duck may have derived its name from incorrect association with Muscovy (the duchy that includes Moscow), or from their musky odor. The scientific name Cairina moschata means “musky one from Cairo,” but the muscovy duck is not from Cairo, either.
More about New world domesticates with Old World names:
Plane takes off, reaches mach 1.3, flies 1K miles, accelerates to mach 2.1, flies 100 mi. How many sonic booms?Posted on November 19th, 2010 No comments
First correct and complete answer was from @jchaager: A plane flying at mach 1 or faster produces one continuous sonic boom which “follows” the plane. At least two people said a supersonic plane makes 1 sonic boom without specifying that it was continuous. Not sure they got it or not.
An airplane, or any other object traveling at the speed of sound or faster produces a sonic boom continually until it decelerates below mach 1. There is a common misconception that a plane produces a singular sonic boom when it “breaks the sound barrier.” Not true. There is an almost equally common misconception that a plane produces another sonic boom at each whole multiple of speed of sound, as it “breaks the second sound barrier” at mach 2, and so on. Not true.
An object moving faster than the speed of sound produces a shock wave which is perceived by an observer as a “sonic boom” as it passes. An observer hears a sonic boom after the airplane passes, even though the plane may have “broken the sound barrier” hundreds of miles away.
One would have hoped that the famous “double sonic boom” of a Space Shuttle on final approach would cure the “sonic boom/sound barrier” myth. The double sonic boom of the Space Shuttle is caused by its curving approach. The shuttle passes the observers twice while still supersonic.
Here in Middle Georgia, sonic booms from U.S. Air Force fighters are a weekly occurrence, but I have a couple of noteable personal experiences with sonic booms.
One day (many years ago) while hunting, I heard sharp “crack” in the trees overhead. About two seconds later, I heard gunshot on next hill. A moment later, this was repeated: A “crack” overhead followed by a distant gunshot two seconds later. What was happening here was that another hunter a mile or so away was shooting at something (and missing), and the bullets were passing my position. Each bullet arrived at my location before the sound of the shot that fired it. As the supersonic bullet passed me, I heard its tiny sonic boom. I didn’t hear the gunshot until that sound had time to travel the mile or so from the shooter’s position to mine.
Now, these bullets “broke the sound barrier” within the barrel of the gun about a mile away from me. But I heard the sonic boom as the bullet passed me. It took a total of about five seconds for the sound of the gunshot – and any sound the bullet may have made by “breaking the sound barrier” – to reach me, but I heard the sonic boom from the bullet 20 feet over my head long before the sound of the gunshot reached me.
There is a very odd phenomenon that may be observed after a sonic boom if the airplane making it passed very close by. I observed this once when a U.S. Navy F-14 “buzzed” my ship while supersonic at mast-top level. The plane had approached from the port side while I was on the starboard side, so I never saw it coming. After the hellaceous blast of the sonic boom, I saw the plane departing very rapidly off the starboard side, and I heard the sound of its departing engines following it. But I also noticed what sounded like another plane’s engines departing rapidly off the port side of the ship, in the direction from which the F-14 had come.
What was happening here was that the sounds made by the plane were “catching up” to my position in reverse order. Sounds made 10 seconds before the plane passed us were arriving at the ship after the sounds made 9 seconds before the plane passed, and so on. This is a perfectly straightforward consequence of the supersonic flight of the plane, but it produces a very disconcerting effect. The observer hears the sounds of the departing plane in “normal” fashion, but the sounds the plane made as it approached are “played in reverse” as earlier sounds catch up to later sounds. It sounds like an invisible airplane flying away.
Ever since that day, whenever I see an airplane approaching but I can’t hear it, I plug my ears and cringe. I have never again heard a sonic boom from mast-top level, but I really, really don’t want to.
More about sonic booms: http://www.sciencetriviatweets.com/?p=1008
Posted on November 16th, 2010 No comments
First correct answer was from @paulsmoffett: The Ganges Delta is the largest delta on Earth.
The Ganges Delta is formed by confluence of the Ganges, Brahmaputra, and Meghna rivers, and some smaller streams. Depending on how you look at it, the Ganges and Hooghly might look like one river, and the Brahmaputra and Meghna as one other river. The Meghna River is actually a combination of a major distributary of the Ganges and a major distributary of the Brahmaputra. It’s all tangled. The Ganges and Brahmaputra have clearly separate headwaters, but as they approach the Bay of Bengal, they seem to turn into one huge braided river with many different names. And they all empty into the denser braids of the Ganges Delta.
One reason the Ganges Delta is so large is that so many rivers contribute to it. Another is that each river has a heavy silt load compared to most rivers on Earth. Most of the rivers feeding the Ganges Delta drain large areas of the rapidly eroding Himalayas, providing rich silt to the delta.
The Ganges Delta encompasses huge wilderness areas, including the largest mangrove swamp in the world, the Sundarbans. It also supports nearly 150 million people with its rich soil and fisheries.
The Ganges Delta comprises much of the nation of Bangladesh, and much of the state of West Bengal, India.
The Ganges Delta is subject to frequent flooding due to the hydrology of the wide, shallow Bay of Bengal directing typhoons to it. Even lesser storms on the Bay of Bengal can cause serious flooding. Flooding in the Ganges Delta is likely to become much worse in the future. Not only is the sea rising due to global warming, the land around the Ganges Delta is subsiding as a result of the continuing tectonic collision of the Indian Subcontinent with Asia.
More about the Ganges Delta: http://en.wikipedia.org/wiki/Ganges_Delta
Posted on November 1st, 2010 No comments
First correct answer was from @rozberk: Many types of cat litter contain microscopic fossil diatoms.
Clumping cat litter usually contains diatomaceous earth, comprised of fossil shells of diatoms, a type of alga with a silica shell. Diatomaceous earth is frequently used in fine filters. It is also used as a fine abrasive, and for absobent materials, such as cat litter. Some diatomaceous earth is used as a supplement to livestock feed due to its deworming capabilities.
The shells of diatoms, settling as sedimentary rock, result in a highly porous form of silica which allows water to pass but traps particles. The diatomaceous earth used in cat litter is usually from freshwater sources, but the more common type is from the sea.
Picturess of diatoms, thanks to @rozberk for the link: http://www.google.com/images?q=diatom At least one image is labeled as a “typical diatom.” A quick scan of the other images will reveal that there’s no such thing as a “typical diatom.”
More about diatoms in cat litter: http://en.wikipedia.org/wiki/Cat_litter#Clumping_litter and http://en.wikipedia.org/wiki/Diatomaceous_earth
What is a leading killer of bats in northeastern North America, threatening species with extinction?Posted on October 26th, 2010 No comments
First correct answer was from @KessCat (@KessBat?): Bats in northeast North America are dying from a mysterious white fungus.
The “white nose syndrome” fungus is killing whole roosting colonies of bats, threatening some populations with extinction. White nose syndrome got its name from white fungal growth on the muzzles and wings of infected bats. The fungus is called Geomyces destructans.
White nose syndrome has been found in bat colonies from Oklahoma and Tennessee to Ontario and Quebec. The fungus only grows in cold conditions, so it kills bats while they hibernate.
It is not certain that the “white nose syndrome” fungus is the direct cause of mass bat fatalaties, or an opportunistic infection that grows on bats that are already terminally sick.
“White nose syndrome” fungus has also been identified in bats in France, but they were not sick. There are interesting implications. This may mean that white nose syndrome originated in Europe, and European bats have some resistance to it. It may also mean that white nose syndrome is not the actual cause of these mass deaths, and the actual cause is not present in Europe.
More about white nose syndrome: http://en.wikipedia.org/wiki/White_nose_syndrome
What are some scientific explanations – none universally accepted – for the Will-o’-the-wisp phenomenon?Posted on October 20th, 2010 No comments
First correct answer was from @little_mavis: Marsh gas is one of the weak scientific explanations for “Will-o’-the-wisp.”
Will-o’-the-wisp, also called Jack-o’Lantern or ignis fatuus (Latin for “fool’s light”), is a weird ball of light often reported in marshy areas.
While reports of Will-o’-the-wisp are frequent enough and widespread enough to elicit some scientific interest, it is too rare to study well. There have been no systematic studies of Will-o’-the-wisp, but many guesses. Since it has never really been systematically studied, we can’t call anything a scientific “explanation” of Will-o’-the-wisp.
Traditional explanations of Will-o’-the-wisp revolve around someone, variously named Will, Jack, or other names, prowling with his lantern. Jack o’ Lantern or Will o’ the Wisp, in various legends is sometimes cursed and sometimes blessed, sometimes benevolent and sometimes evil, depending on the source of the legend and perhaps the mood of the storyteller.
Among the science-based guesses about Will-o’-the-wisp:
- Marsh gas ignited by phosphines, both originating from anaerobic decay.
- Barn owls in moonlight
Some features of Will-o’-the-wisp don’t fit the marsh gas or bioluminescence explantions. For instance, it is said to move in response to the observer. Sometimes it moves toward the observer, and sometimes away. A fire in marsh gas might move at random, but it would probably not be localized, and it would not appear to be interacting with the observer. However, the barn owl explanation fits fairly well with this explanation.
Barn owls have very light-colored and reflective plumage. They fly rather slowly, as all owls do, and their wings are utterly silent as they fly. They are intelligent, curious creatures that might move toward a person at night, but they wouldn’t want to get too close.
I’m rather partial to the barn owl explanation.
More about Will-o’-the-wisp: http://en.wikipedia.org/wiki/Ignis_fatuus
Our word “mummy” comes from Persian for “bitumen.” Did ancient Egyptians use bitumen for mummification?Posted on October 18th, 2010 No comments
No correct answers to this one. No, ancient Egyptians did not use bitumen for mummification, but it was once thought so.
Bitumen was erroneously thought to account for the blackened skin of mummies. In fact, it’s a natural result of dessication.
Egyptian mummification was an elaborate process, but one of the main chemicals used was salt from salt pans and dry lakebeds in the Sahara. These salt deposits consists largely of sodium carbonate decahydrate and sodium bicarbonate, a mixture often called “natron.”
Immersing a body in bitumen might preserve it for a time, but would not likely be as effective as natron. The effect might be similar to the “natural mummification” of bog mummies immersed in peaty mud and water, but not quite. Bitumen would isolate the body from oxygen, but would not be as acidic (and so not quite as hostile to bacteria) as bog water.
More about mummies: http://en.wikipedia.org/wiki/Mummy#Etymology
Today’s Science Trivia: What chemical element that does not exist in nature is installed in most homes in many industrialized countries?Posted on September 27th, 2010 No comments
First correct answer was from @arachne182: Americium, specifically Am-241, is used in smoke detectors. This element does not exist naturally.
Many people answered with elements that don’t exist in elemental form in nature, such as aluminum or tungsten. Not what I was looking for, … We could argue about “what I was looking for” vs. “what the question says.” I think the question says what I meant it to say ;-}
Elements such as most metals do not exist in elemental form on earth because they combine with other elements (especially oxygen). But even if there is no naturally pure aluminum on earth, there is aluminum. And there probably is elemental aluminum in the universe outside Earth’s atmosphere. Probably a lot of it, in fact.
However, transuranic elements with atomic number > 92 exist only under conditions that humans create. They do not exist at all in nature. (Some sources hold that plutonium can exist in nature, but other sources traditionally consider it a synthetic element.)
Americium (atomic number 95) can only be created by neutron bombardment of plutonium or heavier elements. It is a synthetic element.
Most synthetic elements are so highly radioactive that they can only exist very briefly. Once created by neutron bombardment (and subsequent decay), they quickly decay into more stable forms. However, a few isotopes of some transuranic elements are stable enough to last for many years, even thousands of years. They are at least a little radioactive, but they stick around long enough for us to make some use of them.
Most known isotopes of Americium are too unstable to last long. Many are so radioactive that they are too dangerous to handle without special equipment. Am-241 is an exception.
Am-241 is a strong source of alpha radiation and emits very little of other types of radiation. Thus it is safe for use in homes.
This may sound absurd, unless you know a bit about the nature of ionizing radiation. A “pure” alpha source is not at all dangerous to humans, unless it is ingested or inhaled. Properly contained, it could be safely held in your bare hand. The alpha particles it emits can not penetrate the dead layer of skin on your body, so it can not harm living tissue beneath. Of course, there is no such thing as a “pure” alpha source. Even Am-241 emits some gamma radiation, but it emits little enough that a small amount of Am-241 is harmless.
Alpha radiation is very effective at ionizing air, but is completely blocked by the plastic housing of the smoke detector.
An ionizing smoke detector works by passing electric current through ionized air. Smoke blocking the radiation interrupts the current, so the detector knows there is a problem.
Other types of smoke detector do not use Americium or any other source of ionizing radiation. Each type has is advantages, but the ionizing type is very popular due to its low cost and reliability.
More about Americium in smoke detectors: http://en.wikipedia.org/wiki/Smoke_detector#Ionization
More about Am-241: http://en.wikipedia.org/wiki/Americium-241
Recent article claims Pres. Obama is a cactus from the Kalahari. Besides the obvious, what’s wrong with this?Posted on September 22nd, 2010 No comments
A link to the article in question: http://www.theonion.com/articles/poll-1-in-5-americans-believe-obama-is-a-cactus,18127/
(Oh, and just in case you’re not quite following, yes, the article, like everything else on The Onion, is a joke. But there is a science-related error that does not appear to be intentionally incorrect.)
First correct answer was from @jchaager: There are no cacti in the Kalahari.
Many cacti are now feral in many parts of the world, but the cactus family (Cactaceae) originated in the Americas. There are no cacti in the Kalahari.
However, there is a cactus native to Kenya and other parts of tropical Africa. The only cactus naturalized in Africa in prehistoric times is the epiphitic mistletoe cactus (Rhipsalis baccifera), which does not occur in the Kalahari. It is thought to have been spread to Africa from South America by migrating birds just a few thousand years ago.
Now, I like political humor as well as the next person who’s not politically rabid, but I’ll refrain from repeating them on Twitter (at least as far as I have refrained so far). Here are a few notable answers I received in the humor vein:
More about cacti: http://en.wikipedia.org/wiki/Cactus
What is the only “fruit bat” (megachiropterid) known to use echolocation, much as the “insectivorous bats” do?Posted on September 16th, 2010 No comments
Due to Twitter malfunction, I’m not 100% certain who got this right first. I was able to see replies yesterday, including (to the best of my dubious memory) at least a couple of correct answers. Today, I can’t see any replies between September 3 and late morning today (September 17).
The first correct answer may have been from @mlv: Bats of genus Rousettus are the only “fruit bats” (megachiropterids) known to use echolocation. This includes the widespread and fairly well known Egyptian fruit bat (Rousettus egyptiacus).
Microchiropterids (“insectivorous bats”) produce their echolocation sounds with their vocal cords. Bats of genus Rousettus do so by clicking their tongues. This produces a sound that is within the range of human hearing, unlike the very high pitched echolocation sounds of microchiropterid bats.
Interestingly, some blind humans have learned to use echolocation, and some click their tongues for this purpose, just as Rousettus bats do. Others use sounds made by tapping a cane or clapping their hands.
More about Rousettus bats: http://en.wikipedia.org/wiki/Rousettus
More about the Egyptian fruit bat: http://en.wikipedia.org/wiki/Rousettus_egyptiacus
And about human echolocation: http://en.wikipedia.org/wiki/Human_echolocation