biko wrote: » What happens to matter that is sucked into a black hole?
CelticRambler wrote: » 38 weeks from conception, but it seems most doctors and midwives don't trust the mother to know when conception took place, so they backdate the beginning of her pregnancy to the first day of her last period, which is - on average - two weeks before the period of maximum fertility.
The Backwards Man wrote: » And other random questions that have just occurred to you? Seriously though, whoy?
MadDog76 wrote: » Does pregnancy last 9 months (36 weeks) or 40 weeks (10 months)???
Tigger wrote: » When I was a kid I thought that The planets didn't orbit the sun in a rough plane and that they were depicted that way for ease of use I think I realise they do Do they spin the same direction Do they orbit the same direction Will I just look it up?
quickbeam wrote: » Because all the planets orbit the sun roughly in a plane, they'd be seen by both northern and southern cultures - they basically follow the path of the constellations that make up the zodiac - no further north than the Tropic of Cancer and no further south than the Tropic of Capricorn.
The Backwards Man wrote: » Why does a week have seven days? And other random questions that have just occurred to you? Seriously though, whoy?
Peregrinus wrote: » The reason is the one quickbeam points to; the seven-day week is a a convenient division of the lunar month, though as orusan points out it does require adjustment with the insertion of extra days to keep the weeks and months in phase. In the modern calendar we don't do this, which is why any day of the month can fall on any day of the week.
Peregrinus wrote: » Pretty much all cultures divide time based on the seasons, and their signficance for agriculture, hunting, etc. While there are different seasons in different parts of the world, they all work on a one-year cycle, for obvious reasons, so pretty much all cultures develop a calendar in which the solar year is a central element. The Babylonians found observing the heavenly bodies to be a convenient and reliable way of measuring the passage of the seasons, and they built his into their calendar. (The fact that they also imagined the gods to be in the heavens probably helped.) But this doesn't have to be so; the French revolutionary calendar, already mentioned, had twelve months which were named after the weather conditions or agricultural phenomena or activities expected to characterise that time of year. (But the ten days of the revolutionary week had the distinctly unimaginative names of first day, second day, third day, etc.) Indigenous Australian cultures developed a variety of calendars reflecting the seasons in different parts of Australia. They could certainly have used the movements of celestial bodies to measure the passage of time, but I don't know if any of them did. Mostly the months/seasons were named after phenomena that would be important to hunter/gatherer cultures, and the passage of time was marked not by observing the positions or movements of the heavenly bodies, but by observing the immediate environment - the ghost gums are flowering, the Zamia is fruiting, Bunuru has begun, it's time to move down to the coast because the fishing will be good. In some cases months/seasons had two names, on set referring directly to botanical or zoological phenomena and the other referring to some natural cycle applied figuratively to the months of the year. The six months of the Noongar calendar, for example, are named for childhood, adolescence, adulthood, fertility, conception, birth. In other parts of Australia the local people have calendars of two season, three seasons, five seasons, or anything up to 13 seasons.
Mellor wrote: » Well no, because even if their positions are inverted, their speeds don't change. The sun still moves fastest, then the moon, etc. More importantly, the currently calendar is based on a system created by one culture, that spread to other cultures. Antipodeans probably didn't divide their time based on celestial bodies.
The Backwards Man wrote: » Would that not mean antipodean cultures would have had the days mixed up though?
Ted111 wrote: » Jupiter has a seven day week. And so does the Sun. So it can't all be a coincidence.
TheBully wrote: » Even though it would be perfectly possible to imagine a week having five, six or even eleven days, most cultures in the world have seven-day weeks. The reason for this is that seven celestial bodies were known to the ancients: the Sun, the Moon, Mars, Mercury, Jupiter, Venus and Saturn.
TallGlass wrote: » Why isn't time and date metric !
The number seven had a mystical significance to Babylonians. It was associated with the seven heavenly bodies; the Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn. For this reason, some believe, marking rituals every seventh-day became important. A seven-day week based on these same celestial bodies was adopted as far away as Japan and ancient China. Seven is also important in Judaism, where the creation story is told over seven days. But unlike other cultures, in Hebrew the days of the week are assigned numbers not the names of gods, festivals, elements or planets - the only exception is Saturday, Yom Shabbat (יום שבת) which means Sabbath. But the popularity of the seven-day week - and its prominence in modern calendars - can be traced to its adoption by the Romans. They named the days of the week after the pagan gods of Rome, the Sun and the Moon. Roman Emperor Constantine formally adopted the seven-day week in AD 321, it had been in use informally since the first century BC. A Christian convert Constantine made Sunday - the Christian Sabbath - the first day of the week, and Saturday - the Jewish day of rest - as the last.
seamus wrote: » These are the ones you can see with the naked eye. Because they don't always appear and don't appear in the same places all the time, they knew there was something special about these seven. The ordering apparently is something to do with how fast they move across the sky, thus the week starting with the sun, then the moon, etc.
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