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How many times will the Sun cross the southern meridian at Oxford in
2007? How many times will Sirius cross the southern meridian at Oxford in 2007? How many times will the Moon cross the southern meridian at Oxford in 2007? |
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Themos Tsikas wrote:
How many times will the Sun cross the southern meridian at Oxford in 2007? How many times will Sirius cross the southern meridian at Oxford in 2007? How many times will the Moon cross the southern meridian at Oxford in 2007? Given that the answer to each question is different, it is most likely not a trick question; you may learn something from the answers. Best, Stephen Remove footfrommouth to reply -- + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books + + (N51.162 E0.995) | http://astunit.com + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + |
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On Mar 14, 6:17?pm, Stephen Tonkin
wrote: Themos Tsikas wrote: How many times will the Sun cross the southern meridian at Oxford in 2007? How many times will Sirius cross the southern meridian at Oxford in 2007? How many times will the Moon cross the southern meridian at Oxford in 2007? Given that the answer to each question is different, it is most likely not a trick question; you may learn something from the answers. Whilst the moon loses something just under an hour each day compared to the sun as a tidal day is about 55 minutes longer than the solar day, the number of stellar transits will be the same will they not? When does 2007 start and when does it end? Or is that still a matter of choice? |
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This is not homework, although I think it could be a good homework
question. We'll take "2007" to mean what the BBC says it is. The answer to the first one I am confident of: 365 The second one: Viewed from above (north) of the ecliptic, the Earth is going anti-clockwise. So the Sun appears to move to the east. That makes the answer 366. The third one: The moon rises later every day, it moves to the east. So it takes longer to cross the meridian. Say it takes 28 solar crossings for the moon's 27 crossings. Then it will cross 27*365/28 times, that's around 352. To get the right answer, we need a precise figure for the lunar period and the precise location of the Moon when the New Year comes in. |
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On Mar 15, 12:34 pm, "Themos Tsikas"
wrote: This is not homework, although I think it could be a good homework question. We'll take "2007" to mean what the BBC says it is. The answer to the first one I am confident of: 365 Try 2008 which is a leap year with 366 days. The second one: Viewed from above (north) of the ecliptic, the Earth is going anti-clockwise. So the Sun appears to move to the east. That makes the answer 366. Here is where John Flamsteed jumped the tracks by using the return of Sirius to a meridian to justify the motions of the Earth - "... our clocks kept so good a correspondence with the Heavens that I doubt it not but they would prove the revolutions of the Earth to be isochronical..." Flamsteed That is a grave error and completely at variance with the principles which create the equable 24 hour day which in turns creates the 1461 day calendrical cycle. The correlation between clocks and axial rotation at precisely 4 minutes for 1 degree of rotation never requires a reference to any external motion,not the local Sun,not the distant stars,nothing.That they introduced both the Sun and celestial sphere geometry (Fixed stars) in the late 17th century as a gauge for the Earth's motions remains of the greatest astronomical catastrophe imaginable,that being no overstatement. The clock/axial rotation correlation falls out of the original Copernican resolution for retrogrades by invoking an orbital motion for the Earth leaving axial rotation to explain the daily cycle.The timekeepers then overlayed the Equation of Time system on terrestrial geography and treated axial rotation as a constant even if it is not hence the correlation always remains 15 degrees of rotation per hour making exactly 24 hours for each cycle. The 'trick ' question may be explaining these things using a calendar system for the additional day would complicate matters for you whereas I can keep things seperate and assign heliocentric principles to the pre-Copernican observations. The third one: The moon rises later every day, it moves to the east. So it takes longer to cross the meridian. Say it takes 28 solar crossings for the moon's 27 crossings. Then it will cross 27*365/28 times, that's around 352. To get the right answer, we need a precise figure for the lunar period and the precise location of the Moon when the New Year comes in. |
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On Mar 15, 5:34 am, "Themos Tsikas"
wrote: This is not homework, although I think it could be a good homework question. We'll take "2007" to mean what the BBC says it is. The answer to the first one I am confident of: 365 The second one: Viewed from above (north) of the ecliptic, the Earth is going anti-clockwise. So the Sun appears to move to the east. That makes the answer 366. The third one: The moon rises later every day, it moves to the east. So it takes longer to cross the meridian. Say it takes 28 solar crossings for the moon's 27 crossings. Then it will cross 27*365/28 times, that's around 352. To get the right answer, we need a precise figure for the lunar period and the precise location of the Moon when the New Year comes in. Gentlemen, The coords of the Moon for Jan 1, 2008 a 12h 57m 55.2s S 10d 20m 35.9s The orbital longitude for that epoch is 277.3947 deg indicating that the moon is on the wane. The instant of the previous New Moon is Dec 9.737217 (2007) followed by the next New Moon on Jan 8.485031 (2008). There is always one day in every month which is deprived of a transit, moonrise and moonset. For example the transit here in E Arkansas for Mar 2 was 11:35:26.6 pm and the following night was 12:25:44.7 am *on Mar 4*. There was no transit on Mar 3. So 365 - 12 = 353 is a reasonable assumption. I'm curious about Sirius. What's the longitude of Oxford? Ben, 90.126 n 35.539 |
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On Mar 15, 5:34 am, "Themos Tsikas"
wrote: This is not homework, although I think it could be a good homework question. We'll take "2007" to mean what the BBC says it is. The answer to the first one I am confident of: 365 The second one: Viewed from above (north) of the ecliptic, the Earth is going anti-clockwise. So the Sun appears to move to the east. That makes the answer 366. The third one: The moon rises later every day, it moves to the east. So it takes longer to cross the meridian. Say it takes 28 solar crossings for the moon's 27 crossings. Then it will cross 27*365/28 times, that's around 352. To get the right answer, we need a precise figure for the lunar period and the precise location of the Moon when the New Year comes in. Gentlemen, The coords of the Moon for Jan 1, 2008 a 12h 57m 55.2s S 10d 20m 35.9s The orbital longitude for that epoch is 277.3947 deg indicating that the moon is on the wane. The instant of the previous New Moon is Dec 9.737217 (2007) followed by the next New Moon on Jan 8.485031 (2008). There is always one day in every month which is deprived of a transit, moonrise and moonset. For example the transit here in E Arkansas for Mar 2 was 11:35:26.6 pm and the following night was 12:25:44.7 am *on Mar 4*. There was no transit on Mar 3. So 365 - 12 = 353 is a reasonable assumption. I'm curious about Sirius. What's the longitude of Oxford? Ben, 90.126 n 35.539 |
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In uk.sci.astronomy message , Wed, 14 Mar
2007 18:17:09, Stephen Tonkin posted: Themos Tsikas wrote: How many times will the Sun cross the southern meridian at Oxford in 2007? How many times will Sirius cross the southern meridian at Oxford in 2007? How many times will the Moon cross the southern meridian at Oxford in 2007? Given that the answer to each question is different, it is most likely not a trick question; you may learn something from the answers. The answer may not be _quite_ what you think, if the International Standard is followed carefully. Since time immemorial, the idea has been to lock the year to the climatic seasons (granted, others did not do that). Hence the use of the Tropical Year, dependent on the motion of the Earth with respect to that of the Equinoxes. Pope Gregory wanted to lock the Calendar Year to the seasons, but did not do so with perfect accuracy, being about 1 ppm in error IIRC. ISO 8601:2004, however, describes the Gregorian Calendar Year in a manner which can refer only to the Earth's motion with respect to the Fixed Stars. Therefore, there is uncertainty (of about 40 ppm) in the official length of 2007, and maybe a little more. Plus 0.03 ppm for the Leap Second opportunity at the end of UTC December. Readers significantly to the East of Greenwich have no such opportunity. -- (c) John Stockton, Surrey, UK. Turnpike v6.05 IE 6. Web URL:http://www.merlyn.demon.co.uk/ - w. FAQish topics, links, acronyms PAS EXE etc : URL:http://www.merlyn.demon.co.uk/programs/ - see 00index.htm Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc. |
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