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#41
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Lat/Long and timekeeping system for Mars
As a Christian, kind people will always be easily forgiven while dour and unkind people don't need to be forgiven as it is a pointless exercise anyway.. What they don't know in life by experience denies them the value of things in their journey through life.
It is was makes an astronomer, whether creation and the Universe itself or those who give what we have inherited including the great timekeeping system that stretches back to antiquity. It may be 10 years, 100 years, a thousand years or never, however, the structure of a Lat/Long system and 24 hour system for Mars using its own values for Martian hours, minutes and seconds will eventually come into existence as a mirror of the same principles which make Earth's system work so well. The real punishment, at least those who pursue RA/Dec and its hopeless modeling of the Earth's motions, is people do not get to work on that great endeavor. |
#42
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Lat/Long and timekeeping system for Mars
On Wed, 05 Dec 2018 08:43:59 +0100, Paul Schlyter
wrote: On Tue, 04 Dec 2018 13:03:36 -0500, Davoud wrote: I must confess that I have never heard of a "sidereal hour;" Then you haven't computed the local altitude or azimuth for a celestial object either, or it's rise and set time. When doing so, sidereal time is useful. When doing so for the Sun, you can avoid sidereal time by using the Equation of Time instead. While it's obvious that there is such a thing as sidereal time, and that a "sidereal hour" is 1/24 of a sidereal day, the point is that a sidereal day isn't defined by 24 sidereal hours. A sidereal hour is a concept we can understand in terms of a component of sidereal time, but it isn't really used for anything... including the calculations you mention. That is, even a person who does such calculations may never have seen the term "sidereal hour" expressed anywhere. |
#43
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Lat/Long and timekeeping system for Mars
On Wednesday, December 5, 2018 at 8:04:01 AM UTC-8, Gerald Kelleher wrote:
The average 24 hour day for Mars will also be derived from the same inequalities in the natural noon cycle but a Martian hour, Martian minute and Martian second within that average will be entirely different yet will mesh with the planet's 360 degree Latitude and Longitude system organised around the planet's Equator. This will be the structure of a GPS system for vehicles on Mars or other purposes. Gerald, are seriously suggesting that, for Mars, the hour, minute and second will be 'redefined' so that Mars will have a 24 hour rotation period? You are even more delusional than I thought! Why would this possible be an advantage in any way? |
#44
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Lat/Long and timekeeping system for Mars
On Wednesday, December 5, 2018 at 10:03:26 PM UTC-7, palsing wrote:
Gerald, are seriously suggesting that, for Mars, the hour, minute and second will be 'redefined' so that Mars will have a 24 hour rotation period? You are even more delusional than I thought! Why would this possible be an advantage in any way? In fact, *Robert Zubrin* suggested exactly the same thing. While the SI second will obviously be useful on Mars as everywhere else for defining the frequencies of radio waves, and so on and so forth, people living on Mars would want to have a way to refer to *the time of day*, and cutting the day, nearly as long as the day on Earth, into pieces following the same, familiar plan used on Earth is the simplest thing to do. John Savard |
#45
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Lat/Long and timekeeping system for Mars
On Wed, 5 Dec 2018 22:58:41 -0800 (PST), Quadibloc
wrote: On Wednesday, December 5, 2018 at 10:03:26 PM UTC-7, palsing wrote: Gerald, are seriously suggesting that, for Mars, the hour, minute and second will be 'redefined' so that Mars will have a 24 hour rotation period? You are even more delusional than I thought! Why would this possible be an advantage in any way? In fact, *Robert Zubrin* suggested exactly the same thing. While the SI second will obviously be useful on Mars as everywhere else for defining the frequencies of radio waves, and so on and so forth, people living on Mars would want to have a way to refer to *the time of day*, and cutting the day, nearly as long as the day on Earth, into pieces following the same, familiar plan used on Earth is the simplest thing to do. We already do this here on Earth, although the difference between a SI second and a (mean) solar second is much much much much smaller. But we do add leap seconds as needed to UTC to make UTC follow UT1. |
#46
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Lat/Long and timekeeping system for Mars
On Wed, 05 Dec 2018 11:55:12 -0700, Chris L Peterson
wrote: On Wed, 05 Dec 2018 08:43:59 +0100, Paul Schlyter wrote: On Tue, 04 Dec 2018 13:03:36 -0500, Davoud wrote: I must confess that I have never heard of a "sidereal hour;" Then you haven't computed the local altitude or azimuth for a celestial object either, or it's rise and set time. When doing so, sidereal time is useful. When doing so for the Sun, you can avoid sidereal time by using the Equation of Time instead. While it's obvious that there is such a thing as sidereal time, and that a "sidereal hour" is 1/24 of a sidereal day, the point is that a sidereal day isn't defined by 24 sidereal hours. A sidereal hour is a concept we can understand in terms of a component of sidereal time, but it isn't really used for anything... including the calculations you mention. That is, even a person who does such calculations may never have seen the term "sidereal hour" expressed anywhere. The Hour Angle of a celestial object, which is needed to compute its local altitude and azimuth, is most easily computed by subtracting the object's RA from your local sidereal time. Of course you can compute your local sidereal time without labeling it as such or even without even being aware of what it is, but I don't see any convenient way around computing it if you compute the local altitude and azimuth for some celestial object. A nice gadget to have for your observatory is a sidereal clock, which simply tells you the RA of your local meridian. Nowadays a sidereal clock is most easily obtained through a suitable app on your smartphone or tablet. You can also use the sky itself as a sidereal clock. Just find out the RA of your local meridian on a suitable star chart, or in your planetarium software. |
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Lat/Long and timekeeping system for Mars
On Wed, 05 Dec 2018 13:00:32 -0500, Davoud wrote:
*Figuratively speaking. Due to macular degeneration I do not look through telescopes any more. Don't you look at the sky with your naked eyes either anymore? You can use the sky itself as a sidereal clock by finding out on which RA your local meridian is. |
#48
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Lat/Long and timekeeping system for Mars
What makes the structure of timekeeping on Earth such a masterpiece is the seamless count of rotations within a larger cycle known as the calendar cycle. No point in talking about genius and masterpieces among people who can't manage to nail down the Equatorial speed of 1037.5 miles per hour using the 24 hour and Lat/Long system for such people are best left to their own devices.
As the 24 hour day or the 86,400 seconds is already a mathematical average within the framework of rotations and orbital cycles, all refinements are accomplished on that basis. The extra day/rotation (the arbitrary February 29th) is a timekeeping feature which keeps dates as close to the orbital points of Solstices and Equinoxes as possible but further refinements are required to avoid over compensation and this is the way such refinements proceed. The same orbital drift that causes Sirius to skip a first annual appearance by one day is also the same orbital drift which causes the Precession of the Equinoxes. Only in the older timekeeping framework of the Egyptians rather than the Greek framework can this be understood. The first annual appearance of the stars rather than the motion of the Sun through the constellations is inherent in the leap day correction first written down by the astronomers in antiquity. All the contemporary jargon including 'leap seconds' is merely an indication that contemporaries don't have a handle on timekeeping and its close proximity to the rotational and orbital cycles of the Earth therefore the planet Mars will suffer a mongrel system for quite some time or maybe for always.. What took thousands of years to put the system together that works so well for our planet can be done within a lifetime for Mars. If this era wasn't cursed exclusively with celestial sphere enthusiasts (magnification/theorists) then they could have their damn RA/Dec framework without getting in the way of compositional and structural astronomy which recognises the 24 hour and Lat/Long systems as containing the Earth's rotational information as an assertion rather than an observed fact. |
#49
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Lat/Long and timekeeping system for Mars
Quadibloc wrote:
On Wednesday, December 5, 2018 at 10:03:26 PM UTC-7, palsing wrote: Gerald, are seriously suggesting that, for Mars, the hour, minute and second will be 'redefined' so that Mars will have a 24 hour rotation period? You are even more delusional than I thought! Why would this possible be an advantage in any way? In fact, *Robert Zubrin* suggested exactly the same thing. While the SI second will obviously be useful on Mars as everywhere else for defining the frequencies of radio waves, and so on and so forth, people living on Mars would want to have a way to refer to *the time of day*, and cutting the day, nearly as long as the day on Earth, into pieces following the same, familiar plan used on Earth is the simplest thing to do. John Savard Mars wris****ches have existed for years. They are used by the operators of Mars landers who need to start their shift times earlier every day. Since the first of these were slowed down Earth time watches they implicitly use Martian seconds. https://hackaday.com/2012/09/09/buil...sitys-drivers/ For human settlers on Mars I like the “witching hour” method of Vernor Vinge from Across Realtime where the standard Earth time is used with an extra period tagged onto the end of the day. But this would have problems with geographically (areographically) separated settlements. |
#50
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Lat/Long and timekeeping system for Mars
Paul Schlyter wrote:
On Wed, 05 Dec 2018 11:55:12 -0700, Chris L Peterson wrote: On Wed, 05 Dec 2018 08:43:59 +0100, Paul Schlyter wrote: On Tue, 04 Dec 2018 13:03:36 -0500, Davoud wrote: I must confess that I have never heard of a "sidereal hour;" Then you haven't computed the local altitude or azimuth for a celestial object either, or it's rise and set time. When doing so, sidereal time is useful. When doing so for the Sun, you can avoid sidereal time by using the Equation of Time instead. While it's obvious that there is such a thing as sidereal time, and that a "sidereal hour" is 1/24 of a sidereal day, the point is that a sidereal day isn't defined by 24 sidereal hours. A sidereal hour is a concept we can understand in terms of a component of sidereal time, but it isn't really used for anything... including the calculations you mention. That is, even a person who does such calculations may never have seen the term "sidereal hour" expressed anywhere. The Hour Angle of a celestial object, which is needed to compute its local altitude and azimuth, is most easily computed by subtracting the object's RA from your local sidereal time. Of course you can compute your local sidereal time without labeling it as such or even without even being aware of what it is, but I don't see any convenient way around computing it if you compute the local altitude and azimuth for some celestial object. A nice gadget to have for your observatory is a sidereal clock, which simply tells you the RA of your local meridian. Nowadays a sidereal clock is most easily obtained through a suitable app on your smartphone or tablet. You can also use the sky itself as a sidereal clock. Just find out the RA of your local meridian on a suitable star chart, or in your planetarium software. I really like Emerald Observatory for the iPad. And it now costs less than a dollar. http://www.macobserver.com/tmo/artic..._dead_gorgeous |
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