CULTURAL QA 12-2023-07 All the BELOW QA arefrom Quora DIGEST to me on 07-12-2023.
QUORA ANSWERS NEED NOT BE 100%CORRECT ANSWERS. Compiled and posted by R. Gopala Krishnan, 80, on 07-12-2023. Q1 If Venus is closer to theEarth, why did we land on the Moon? A1 RonBrown, Occasional observer of our larger environment. Jul 19 Here is a picture I took of Venus and a crescent Moon(in Nov. 2021). If Venus iscloser to Earth than the Moon, perhaps we considered it too small to land on. Well, either that or Venus is much farther away than theMoon. The Moon is about a quarter a million miles away fromEarth. Earth is about 93 million miles away from the Sun. Venus is about 67 million miles fromthe Sun. So its closest distance to Earth is 26 million miles - when it isdirectly between Earth and the Sun. Thatis, the closest Venus ever is relative to Earth is about 100 times as far awayas the Moon. So that might be the reason. Another is that Venus is a very hostileenvironment - at 900°F - not a pleasant place to land. Q2 Why do airplanes useheadlights at night? What are they trying to see? A2 RebeccaWilliams, Experience in Aviation16h Airplanes useheadlights at night for two main reasons: to see and to be seen. The lights on airplanes are not thesame as the headlights on cars. They are called landing lights, and they are much brighter and morepowerful than car headlights.They are also mounted on different parts of the airplane, such as the wings,the fuselage, or the landing gear. The first reasonwhy airplanes use landing lights at night is to see the runway and the surroundings when taking offor landing. Landing lightshelp pilots avoid obstacles, people, or vehicles on the runway, as wellas identify the runway markings and edges. Landing lights areusually turned on when the airplane is below 10,000 feet, which is the altitude where mosttake offs and landings occur. Landing lights are also useful for flying in low-visibility conditions,such as fog, rain, or snow. The second reason why airplanes use landing lights at night is to be seenby other airplanes and air traffic controllers. Landing lights make airplanes more visible in thedark sky, especially when they are flying close to the airport or in busyairspace. Landinglights help prevent collisions between airplanes, as well as alertcontrollers of the airplane’s position and intention. Landing lights are alsoused as a signal to communicate with other pilots or controllers, such asflashing them to indicate a change of course or a request for Q3 Are there any real life"lost world" ecosystems? A3 GaryMeaney, passionate fan of all things animal2y My note- 10 Pages answer. Read atleisure time. Very informative answer. In the northeast of South America, there lies asprawling geological formation known as the Guiana Shield; an expanse of 1.7 billion year old rock.Long ago, it was a high plateau of sedimentary stone, but most of it has sincebeen eroded away. What remains ofthis ancient highland are immense blocks of sandstone, flattened at the top. The local Pemon people callthem tepuis, meaning“houses of the gods”, and there are hundreds of them. Most tepuis are scattered across Venezuela, but theyextend into neighbouring Guyana and Brazil too. Outside of the Andes, these tabletop mountains are amongthe tallest landforms in South America. You have MountRoraima, the inspiration for Arthur Conan Doyle’s The Lost World: Auyán-tepui, hometo the world’s tallest waterfall: Cerro Autana, amountain which has a cave cutting right through it, with an opening on either side: Sarisariñama,the surface of which is stippled with massive sinkholes: And many more.Towering high above the forests and savannahs, surrounded by sheer cliffs on all sides, tepuis are just as remote andinaccessible as islands in the sea; they are effectively islands in the sky.And, just like marine islands, they have a unique array of wildlife whichevolved in a vacuum, cut off from the “mainland”. Before I introduce you to the flora and fauna ofthese mountains, I’ll go over some of their most interesting physicalcharacteristics which make them such unique environments. Most tepuis are surrounded onall sides by abrupt vertical cliff faces. On top,the terrain varies, but you’ll often find these otherworldly rock formationsknown as stone forests. Here, the elements have eroded the soluble rock into complex pavementsof grooves, pillars and furrows. Sometimes, thegouged-out depressions fill up with water, which is then colonized by colourfulalgae. Erosion hascreated many other spectacular features on tepuis. There are innumerable caverns beneath thetabletops, most of them unexplored. As they are formedof quartzite, an incredibly hard mineral, they must have taken hundreds ofmillions of years to form, and may be the oldest caves on Earth. Some of the chambers are massive (look at the size ofthe person in the bottom left, below), and one - Abismo Guy Collet - is thedeepest cave in all of South America, at a depth of 671 metres. It’s also the world’s deepest quartzitecave. Inside the caverns, there are subterranean lakes andrivers, bizarre rock formations, ancient microbial growths, and wildlife suchas blind fish, scorpions, spiders and giant cave crickets. When the rock above these caverns collapse, sinkholesform. There are many sinkholes pockmarking Venezuela’s tepuis, some of themmeasuring over 300 metres, both in diameter and depth. CerroSarisariñama, a specific tepui, is particularly famous for its holes,which are themselves so isolated that there may be species at the bottomendemic to each particular sinkhole. And then ofcourse there are the waterfalls. When rivers spill over the edge of the mesas, theyform some of the most spectacular falls on Earth. The mostwell-known is Angel Falls, the world’s tallest waterfall, plunging nearly akilometre down to the lowlands below. Other notable examples include Kukenán Falls, whichisn’t quite as towering, but still extraordinarily tall at 610 metres: And Kaieteur Falls, the world’s largest single-dropwaterfall in terms of total volume: Now, let’s takea look at the wildlife found on these sky islands. In the bare limestone pavements and stone forests,there isn’t much real estate for plant life, but a handful of hardy species ekeout an existence in the cracks. Some plantspecies here are only found on one particular tepui, and about a third of the totalflora is endemic to the Guiana Shield. Bromeliads, close relatives of the pineapple, areespecially common. The small treeswhich manage to grow on the rocks, such as Bonnetia roraimae, are quite alien indeed. The reddishcolour of their leaves is due to anthocyanin pigments, which help protect them againstextremes of weather. Thered-brown hue of the vegetation on some tepuis can even be seen from space: Another thing about these rocky areas is that what soil there is very thinand poor in nutrients. Asa result, some plants use an alternative source of nutrition - animals.Carnivorous flora is common here, including pitcher plants which drown insects in digestivenectar: And sundews.Their leaves are covered in mucus-coated hairs, and when flies get stuck in the secretion, the leafrolls up, constricting the prey and slowly digesting it. The conditions atop tepuis are not always sounforgiving, however. Some summits feature shrublands, savannahs, and densetropical forests. Then there’s the animal inhabitants. Just like the plants, tepui faunashows high levels of endemism, meaning that many species are found nowhereelse. The limited space and scarcity of food mean that therearen’t any very big animals atop the plateaus, but there’s still plenty offascinating wildlife. Although colonist species from the lowlands probablydo come in every now and then, mostof the wildlife on the tepuis is likely descended from animals that were therebefore the surrounding land was eroded away. Their ecosystems guarded bysheer cliffs, said animals evolved in isolation from the rest ofthe world. Let’s start withthe endemic birds. This includes the tepui tinamou, an elusive ground-dwelling bird: The Roraiman nightjar, which is nocturnal: A wide varietyof hummingbirds, including the tepui goldenthroat and the peacock coquette (pictured): The tepui parrotlet, which commutes between mountaintops in flocks ofseveral hundred: The greater flowerpiecer, often found on the barren karstrocks, which perforates the base of flowers to access nectar: The colourful tepui brushfinch: And many birds in the group Tyranni, such as theRoraiman antwren: And the striking scarlet-horned manakin, which has apair of feathery tufts on its head (its “horns”): While the forested foothills of the mesas are rich inmammal fauna, the challenging conditions at the top (and the inaccessibility)mean that there aren’tmany mammals here. Those that are are usually quite small. Some endemic examples include Tyler’s mouse-opossum, which Idon’t think has ever been photographed (a close relative is shown): McConnell's climbing rat (again, a closely related species isis shown below): Isabelle’s ghostbat (again, not the exact same speciesin the photo): And the prickly Roraima mouse, which was thought extinct until itsrediscovery in 2009. The picture is correct this time. What’s especially interesting about this mouse isthat its closest genetic relatives are not found on the lowlands surroundingthe tepuis, but way over atop the Brazilian Shield on the other side of theAmazon Basin. This is because its ancestors inhabited a vast South Americanplateau which has now been mostly eroded. In the remaining Guianan andBrazilian shields, this lineage of mice has survived. There are only two “large" animals which are definitively known tolive on top of tepuis: the brown-nosed coati and the southern tamandua, aspecies of anteater. We have photographic evidence in both cases. There are, however, reports of giant anteaters,pale-throated sloths and even jaguars from the summits. None of these animals have been observed here inmodern times, though, and the last claim is especially dubious. Now for the herpetofauna; the reptiles and amphibians. There are many endemic species,including an incredible diversity of frogs, of which 90 percent are endemic, but not too many whichreally stand out. I will however mention a few, such as the lizard Pantepuisaurusrodriguesi. It's not just an endemic species, but a whole unique genus, foundonly on tepuis. Its close relative, Riolama inopinata, is alsoendemic, and has a striking red colouration. There's also the Neblina anole, a fairly large lizard which canextend a brightly coloured dewlap from its throat: The Roraima bush toad, a creature that — whenthreatened — curls up and rolls away: And the tepui treefrog, which carries its young on its back. The last component of the tepui wildlife left toreview is the invertebratefauna. There are countless endemic beetles, snails, butterflies, andeven aquatic insects and crustaceans in underground rivers. The only endemic arthropod species which I findparticularly noteworthy are an assortment of freshwater crabs recently discovered in the mountains'forests. So, that's basically everything you need to knowabout these extraordinary evolutionary laboratories. There is doubtless much left to discover here;many tepuis have long been near-impossible to access even by helicopter, butthey're beginning to reveal their secrets. Thank you everyone for reading! I had a lot of funcomposing this answer, so hopefully you'll get some enjoyment out of it. -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/thatha_patty/1152795416.761144.1701929958934%40mail.yahoo.com.
