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David Knisely wrote in newsX5Ib.258$eF1.67@fe10:
Sidereal time is determined by the rotation of the earth with refernce to the equinox. It takes 23h56m to make a 360 degree rotation. Well, not quite, although if you mean referenced to a point on the celestial sphere like the vernal or autumnal equinoxes, you would be right. Dave, It's what I meant as this is the reference for measuring the length of a tropical sidereal day ie to the precessing mean equinox (moving RA/Dec system) and actually is not quite 360 degrees (359.99996...°) :-) Sidereal time is determined by the rotation rate with respect to the stars. The Earth rotates 360 degrees with respect to the stars in a period of 23 hrs, 56 minutes, 4.092 seconds. We generally say that local sidereal time is the right ascension of the local meridian (or the hour-angle of the vernal equinox). Clear skies to you. Martin |
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Martin Lewicki wrote in message ...
(Oriel36) wrote in om: Martin Lewicki wrote in message ... DaveC wrote in al.net: How does LST correlate to our terrestrial time? I'm not looking for a definition, or an explanation that includes angles of the equinox, or such. I just want to know if a particular time in LST is fixed in relation to the clock on the wall, or if it changes over the year, and how to calculate it or look it up. Thanks, Here are the principles. Sidereal time is determined by the rotation of the earth with refernce to the equinox. It takes 23h56m to make a 360 degree rotation. Thoroughly incorrect. It is necessary to define a 24 hour day first before you determine that the annual cycle is 365.25 days. The basis for the 24 hour clock day relies on the axial rotation in 24 hours exactly and accurate clocks were developed by John Harrison on that principle. http://rubens.anu.edu.au/student.pro...aval/defin.htm Agreed, in a mean solar day the earth rotates through 360 *degrees of longitude*, but rotates nearly 361 degrees in space, ie in reference to a fixed star on the celestial sphere. Do you wish to try again with that one as you got it wrong and understand that it may have been due to carelessness rather than anything else. Clock time based on a mean solar time and is the rotation of the earth with refernce to a mean Sun. It is 24h00m and a 361 degree rotation. Thoroughly incorrect. Nothing rotates more than 360 degrees and clocks maintain the 24 hour/360 degree equivalency for the axial rotation of the Earth.The principles behind clocks for solving the longitude problem is that it is noon along an entire longitude meridian at some location on the planet. It follows by your argument the moon does not rotate because it maintains same face to earth. I assure you that it is noon along a given longitude meridian at any given moment as the Earth rotates to face the Sun directly. As the observed effect of noon is conditioned by constant axial rotation and variable orbital motion of the Earth you can safely acknowledge that there will be a natural inequality from one complete axial rotation to the next.Sundial register the motions of the Earth using the Sun as a reference and the pace of the shadow across the dial varies in accordance with the combined effect of constant axial rotation and variable orbital motion. Because there is no observed equality from one axial rotation to the next,brilliant men devised a computation known as the Equation of Time to equalise the variation from one axial rotation to the next or what amounts to the same thing,one 24 hour day to the next. Fair enough but equation of time is not relevant to the principles of this argument. The EoT facilitates the seamless transition from one 24 hour day to the next and subsequently distinguishes the natural variable day from the 24 hour clock day by means of axial rotation. You cannot define a sidereal day without first determining where a 24 hour day comes from.For astronomical and navigation purposes the 24 hour day is taken as the axial rotation of the Earth through 360 degrees and accurate clocks were developed by John Harrison on that precise geometric/astronomical principal.To argue otherwise is foolish yet siderealists argue for the direct linking of the Earth's rotation through 360 degrees to stellar circumpolar motion. So,siderealists say 23 hours 56 min 04 sec for rotation through 360 degrees when the figure is actually 24 hours precisely.The 24 hour clock sets the pace of everything else including stellar circumpolar motion but there is no justification in linking axial rotation through 360 degrees to that figure.,big error and big trouble. Why 361 degrees? Sun advances nearly 1 degree in the ecliptic every sidereal day. Therefore the earth must rotate a further 1 degree or 4 minutes to catch up to complete a solar day. By the sidereal method .986 deg or 3 min 56 seconds. Because the true rotation rate is calculated as 24 hours = 360 degrees ...of longitude on the earth's surface (or 361 deg in space). Those who enjoy the rediscovery of clocks for solving the longitude problem and why it was crucial to retain a consistent accurate pace from one day to the next should enjoy the mathematical EOT computation which equalises the lenght of the natural day from noon to noon by addition and subtraction of minutes and seconds.Applying the EoT to the noon observation allowed navigators to calculate their position to a clock which maintained position at another longitude meridian,the difference corresponding to 4 minutes clock time per degree and 24 hours per 360 degrees. 1 deg = 4 min clock time .986 deg = 3 min 56 sec clock time 24 hours minus 3 min 56 sec = 23 hours 56 min 04 sec. http://www.absolutebeginnersastronomy.com/sidereal.gif The catastrophic error is that you need to define a 24 hour clock day first before you determine that there is 365 days 5 hours and 49 min in an annual cycle and all justifications for the sidereal value begin on the wrong footing,the day is defined by the axial rotation of the Earth via the Equation of Time and insofar as this reflects the 24 hour/360 degree equivalency. Newton,in defining the difference between the natural unequal day and the constant 24 hour clock day as the Equation of Time or the difference between absolute time and relative time may have unwittingly paved the way for tampering with the original determination of the day linked to the isolation of the Earth's rotation to 24 hours/360 degrees. "Absolute time, in astronomy, is distinguished from relative, by the equation or correlation of the vulgar time. For the natural days are truly unequal, though they are commonly considered as equal and used for a measure of time; astronomers correct this inequality for their more accurate deducing of the celestial motions. It may be, that there is no such thing as an equable motion, whereby time may be accurately measured." Principia http://members.tripod.com/~gravitee/definitions.htm The price of tampering with the association between axial rotation through 360 degrees and the 24 hour clock as Newton's absolute time is that in the 21st century,men believe that the Earth has a constant equable motion through 360 degrees and that motion is stellar circumpolar motion. Not even the creationist doctrine can compare to reasoning that links the Earth's rotation directly to the sidereal value and stellar circumpolar motion for ultimately it leads to the stellar circumpolar framework. http://home.t-online.de/home/sjkowollik/polaris.jpg Now are you certain that the Earth's axial rotation through 360 degrees corresponds to the return of a reference star to the same position in 23 hours 56 min 04 sec. The sidereal clock thus gains 4 minutes accumulatively on a solar clock every day. The Equation of Time (EoT) contains positive and negative values of minutes and seconds which were applied at observed noon to maintain the transition from one 24 hour clock day to the next or one axial rotation to the next.The EoT equalises the variation in a natural day by treating axial rotation as constant and modifying the variation in orbital motion due to Kepler's second law which generates the natural inequality for each axial rotation. Again,you cannot even to begin to define the sidereal value without the 24 hour/360 degree equivalency but it appears that it does not stop you from trying. http://www.burnley.gov.uk/towneley/tryall/eot3.htm The two clocks are by convention synchronized at 00h00m at the September equinox. Thereafter they diverge by 4 minutes per day until they are 12 hours apart 6 months later at the March equinox. They contiune until they once more synchronize at the following September equinox. Martin Lewicki Clocks and the longitude problem,the only means to sort all this out and restore the Earth's axial rotation to the 24 hour/360 degree equivalency.It does not matter that men got it badly wrong in 1905 by tampering with the definition of a constant 24 hour day from the natural unequal day via the EoT,it is a matter of appreceation. "In default of better information we may without serious error (in days of sail) take the recorded hour as in the apparent time of the meridian of longitude mentioned in the account, and for form's sake apply the equation of time to reduce to civil time of the meridian." http://www.aandc.org/research/nautic..._and_date.html I assure you that the Earth takes 24 hours to rotate 360 degrees ...of longitude It is no longer up to me to present the observational and historical designation of the 24 hour day from the natural unequal day which in turn generates determination of the sidereal value.The error is fixing the Earth's 360 degree rotation directly to stellar circumpolar motion or 23 hours 56 min 04 sec and the error is so obvious that it siderealism may constitute a belief akin to creationism . The price of tampering with Newton's phrasing of the Equation of Time is a Piltdown man scenario to the power of ten. "Absolute time, in astronomy, is distinguished from relative, by the equation or correlation of the vulgar time. For the natural days are truly unequal, though they are commonly considered as equal and used for a measure of time; astronomers correct this inequality for their more accurate deducing of the celestial motions. It may be, that there is no such thing as an equable motion, whereby time may be accurately measured." Principia on its axis,that is the way it always was and will be.Ask anyone on the street and they will tell you,they may not know the particulars of defining a 24 hour day but it appears neither do you,no offense intended. Offense not taken. Seems definitions are a matter of relative perspective :-) Martin |
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"Martin Lewicki" wrote in message
... I'm afraid I remain unconvinced by your arguements. I must say I find them somewhat obscure. And you will continue to do so... he's a kook. |
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Martin Lewicki wrote in message ...
(Oriel36) wrote in om: Martin Lewicki wrote in message ... (Oriel36) wrote in om: Martin Lewicki wrote in message ... DaveC wrote in al.net: How does LST correlate to our terrestrial time? I'm not looking for a definition, or an explanation that includes angles of the equinox, or such. I just want to know if a particular time in LST is fixed in relation to the clock on the wall, or if it changes over the year, and how to calculate it or look it up. Thanks, Here are the principles. Sidereal time is determined by the rotation of the earth with refernce to the equinox. It takes 23h56m to make a 360 degree rotation. Thoroughly incorrect. It is necessary to define a 24 hour day first before you determine that the annual cycle is 365.25 days. The basis for the 24 hour clock day relies on the axial rotation in 24 hours exactly and accurate clocks were developed by John Harrison on that principle. http://rubens.anu.edu.au/student.pro...aval/defin.htm Agreed, in a mean solar day the earth rotates through 360 *degrees of longitude*, but rotates nearly 361 degrees in space, ie in reference to a fixed star on the celestial sphere. Do you wish to try again with that one as you got it wrong and understand that it may have been due to carelessness rather than anything else. I'm afraid I remain unconvinced by your arguements. I must say I find them somewhat obscure. Martin Who cares whether you are convinced or not,you don't have a choice in the matter. The reason you find them obscure is that you obviously never heard of John Harrison,the longitude problem and how clocks solved the determination of position on the planet by acting as rulers of distance,needless to say it is because the Earth rotates on its axis in 24 hours through 360 degrees and consequently 15 degrees per hour and 4 min per 1 degree. I must say,ol boy,that nothing can be more boring than people who attach the name 'astronomer' to themselves and can't figure out the 24 hour/360 degree equivalecy for the axial rotation of the Earth while trying to justify it as 23 hours 56 min 04 sec. Clock time based on a mean solar time and is the rotation of the earth with refernce to a mean Sun. It is 24h00m and a 361 degree rotation. Thoroughly incorrect. Nothing rotates more than 360 degrees and clocks maintain the 24 hour/360 degree equivalency for the axial rotation of the Earth.The principles behind clocks for solving the longitude problem is that it is noon along an entire longitude meridian at some location on the planet. It follows by your argument the moon does not rotate because it maintains same face to earth. I assure you that it is noon along a given longitude meridian at any given moment as the Earth rotates to face the Sun directly. As the observed effect of noon is conditioned by constant axial rotation and variable orbital motion of the Earth you can safely acknowledge that there will be a natural inequality from one complete axial rotation to the next.Sundial register the motions of the Earth using the Sun as a reference and the pace of the shadow across the dial varies in accordance with the combined effect of constant axial rotation and variable orbital motion. Because there is no observed equality from one axial rotation to the next,brilliant men devised a computation known as the Equation of Time to equalise the variation from one axial rotation to the next or what amounts to the same thing,one 24 hour day to the next. Fair enough but equation of time is not relevant to the principles of this argument. The EoT facilitates the seamless transition from one 24 hour day to the next and subsequently distinguishes the natural variable day from the 24 hour clock day by means of axial rotation. You cannot define a sidereal day without first determining where a 24 hour day comes from.For astronomical and navigation purposes the 24 hour day is taken as the axial rotation of the Earth through 360 degrees and accurate clocks were developed by John Harrison on that precise geometric/astronomical principal.To argue otherwise is foolish yet siderealists argue for the direct linking of the Earth's rotation through 360 degrees to stellar circumpolar motion. So,siderealists say 23 hours 56 min 04 sec for rotation through 360 degrees when the figure is actually 24 hours precisely.The 24 hour clock sets the pace of everything else including stellar circumpolar motion but there is no justification in linking axial rotation through 360 degrees to that figure.,big error and big trouble. Why 361 degrees? Sun advances nearly 1 degree in the ecliptic every sidereal day. Therefore the earth must rotate a further 1 degree or 4 minutes to catch up to complete a solar day. By the sidereal method .986 deg or 3 min 56 seconds. Because the true rotation rate is calculated as 24 hours = 360 degrees ...of longitude on the earth's surface (or 361 deg in space). Those who enjoy the rediscovery of clocks for solving the longitude problem and why it was crucial to retain a consistent accurate pace from one day to the next should enjoy the mathematical EOT computation which equalises the lenght of the natural day from noon to noon by addition and subtraction of minutes and seconds.Applying the EoT to the noon observation allowed navigators to calculate their position to a clock which maintained position at another longitude meridian,the difference corresponding to 4 minutes clock time per degree and 24 hours per 360 degrees. 1 deg = 4 min clock time .986 deg = 3 min 56 sec clock time 24 hours minus 3 min 56 sec = 23 hours 56 min 04 sec. http://www.absolutebeginnersastronomy.com/sidereal.gif The catastrophic error is that you need to define a 24 hour clock day first before you determine that there is 365 days 5 hours and 49 min in an annual cycle and all justifications for the sidereal value begin on the wrong footing,the day is defined by the axial rotation of the Earth via the Equation of Time and insofar as this reflects the 24 hour/360 degree equivalency. Newton,in defining the difference between the natural unequal day and the constant 24 hour clock day as the Equation of Time or the difference between absolute time and relative time may have unwittingly paved the way for tampering with the original determination of the day linked to the isolation of the Earth's rotation to 24 hours/360 degrees. "Absolute time, in astronomy, is distinguished from relative, by the equation or correlation of the vulgar time. For the natural days are truly unequal, though they are commonly considered as equal and used for a measure of time; astronomers correct this inequality for their more accurate deducing of the celestial motions. It may be, that there is no such thing as an equable motion, whereby time may be accurately measured." Principia http://members.tripod.com/~gravitee/definitions.htm The price of tampering with the association between axial rotation through 360 degrees and the 24 hour clock as Newton's absolute time is that in the 21st century,men believe that the Earth has a constant equable motion through 360 degrees and that motion is stellar circumpolar motion. Not even the creationist doctrine can compare to reasoning that links the Earth's rotation directly to the sidereal value and stellar circumpolar motion for ultimately it leads to the stellar circumpolar framework. http://home.t-online.de/home/sjkowollik/polaris.jpg Now are you certain that the Earth's axial rotation through 360 degrees corresponds to the return of a reference star to the same position in 23 hours 56 min 04 sec. The sidereal clock thus gains 4 minutes accumulatively on a solar clock every day. The Equation of Time (EoT) contains positive and negative values of minutes and seconds which were applied at observed noon to maintain the transition from one 24 hour clock day to the next or one axial rotation to the next.The EoT equalises the variation in a natural day by treating axial rotation as constant and modifying the variation in orbital motion due to Kepler's second law which generates the natural inequality for each axial rotation. Again,you cannot even to begin to define the sidereal value without the 24 hour/360 degree equivalency but it appears that it does not stop you from trying. http://www.burnley.gov.uk/towneley/tryall/eot3.htm The two clocks are by convention synchronized at 00h00m at the September equinox. Thereafter they diverge by 4 minutes per day until they are 12 hours apart 6 months later at the March equinox. They contiune until they once more synchronize at the following September equinox. Martin Lewicki Clocks and the longitude problem,the only means to sort all this out and restore the Earth's axial rotation to the 24 hour/360 degree equivalency.It does not matter that men got it badly wrong in 1905 by tampering with the definition of a constant 24 hour day from the natural unequal day via the EoT,it is a matter of appreceation. "In default of better information we may without serious error (in days of sail) take the recorded hour as in the apparent time of the meridian of longitude mentioned in the account, and for form's sake apply the equation of time to reduce to civil time of the meridian." http://www.aandc.org/research/nautic..._and_date.html I assure you that the Earth takes 24 hours to rotate 360 degrees ...of longitude It is no longer up to me to present the observational and historical designation of the 24 hour day from the natural unequal day which in turn generates determination of the sidereal value.The error is fixing the Earth's 360 degree rotation directly to stellar circumpolar motion or 23 hours 56 min 04 sec and the error is so obvious that it siderealism may constitute a belief akin to creationism . The price of tampering with Newton's phrasing of the Equation of Time is a Piltdown man scenario to the power of ten. "Absolute time, in astronomy, is distinguished from relative, by the equation or correlation of the vulgar time. For the natural days are truly unequal, though they are commonly considered as equal and used for a measure of time; astronomers correct this inequality for their more accurate deducing of the celestial motions. It may be, that there is no such thing as an equable motion, whereby time may be accurately measured." Principia on its axis,that is the way it always was and will be.Ask anyone on the street and they will tell you,they may not know the particulars of defining a 24 hour day but it appears neither do you,no offense intended. Offense not taken. Seems definitions are a matter of relative perspective :-) Martin |
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"Greg Neill" wrote in message m...
"Martin Lewicki" wrote in message ... I'm afraid I remain unconvinced by your arguements. I must say I find them somewhat obscure. And you will continue to do so... he's a kook. I don't know why you are sour,the Equation of Time and the understanding of it seperates the natural unequal day from the equable 24 hour clock day.If you want to believe that the Earth's rotation is 23 hours 56 min 04 seconds through 360 degrees then be my guest but clocks were developed on the principle of axial rotation through 360 degrees in precisely 24 hours giving terms such as Monday,Tuesday,Wednesday... http://tea.rice.edu/loomer/7.18.2003.html Perhaps you are new to astronomy and have yet to figure out that you are required to define a 24 hour day first before you divide it into a annual cycle and come up with a figure of 365 days 5 hours 49 min (365.25 days),in any case,I assure you that linking the Earth's rotation through 360 degrees to stellar circumpolar motion is ,well,idiotic and the sidereal value is only useful for image collecting and nothing else. Now you don't want to be compared with creationists do you ?,for surely the basis for axial rotation and the 24 hour day is not at all difficult to understand and is within the range of most people. |
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In message , Oriel36
writes Who cares whether you are convinced or not,you don't have a choice in the matter. The reason you find them obscure is that you obviously never heard of John Harrison,the longitude problem and how clocks solved the determination of position on the planet by acting as rulers of distance,needless to say it is because the Earth rotates on its axis in 24 hours through 360 degrees and consequently 15 degrees per hour and 4 min per 1 degree. I must say,ol boy,that nothing can be more boring than people who attach the name 'astronomer' to themselves and can't figure out the 24 hour/360 degree equivalecy for the axial rotation of the Earth while trying to justify it as 23 hours 56 min 04 sec. So long, you offensive little troll. On the subject of clocks, remember my response to your "contribution" to one of the Pioneer threads. Plonk. -- Rabbit arithmetic - 1 plus 1 equals 10 |
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"Oriel36" wrote in message
om... "Greg Neill" wrote in message m... "Martin Lewicki" wrote in message ... I'm afraid I remain unconvinced by your arguements. I must say I find them somewhat obscure. And you will continue to do so... he's a kook. I don't know why you are sour,the Equation of Time and the understanding of it seperates the natural unequal day from the equable 24 hour clock day.If you want to believe that the Earth's rotation is 23 hours 56 min 04 seconds through 360 degrees then be my guest but clocks were developed on the principle of axial rotation through 360 degrees in precisely 24 hours giving terms such as Monday,Tuesday,Wednesday... http://tea.rice.edu/loomer/7.18.2003.html Perhaps you are new to astronomy and have yet to figure out that you are required to define a 24 hour day first before you divide it into a annual cycle and come up with a figure of 365 days 5 hours 49 min (365.25 days),in any case,I assure you that linking the Earth's rotation through 360 degrees to stellar circumpolar motion is ,well,idiotic and the sidereal value is only useful for image collecting and nothing else. Now you don't want to be compared with creationists do you ?,for surely the basis for axial rotation and the 24 hour day is not at all difficult to understand and is within the range of most people. Kook. |
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