RA/Dec limitations

Over the last decade a narrative was introduced that asserted a slowing rotation ,first from making close range observations and then extended out in history as a general principle -

"At the time of the dinosaurs, Earth completed one rotation in about 23 hours," says MacMillan, who is a member of the VLBI team at NASA Goddard. "In the year 1820, a rotation took exactly 24 hours, or 86,400 standard seconds.. Since 1820, the mean solar day has increased by about 2.5 milliseconds." NASA

http://www.nasa.gov/topics/solarsyst...ra-second.html

This is at variance with 20 years ago when the 'solar vs sidereal' framework was proposed to ascertain rotation once in 23 hours 56 minutes 04 seconds along with 366.25 rotations per orbital circuit -

"As seen in Figure 4, the Earth must rotate a bit more for a mean solar day than for a sidereal day. In fact, a sidereal day is only 23h56m04s.09054 of mean solar time. This difference, while small, is extremely important."

https://celestrak.com/columns/v02n01/


At this stage there is no pretense whatsoever - instead of untangling the damage done a few centuries ago that, in order to served the contrived purpose of a 'leap second' , contemporaries are willing to dig a deeper hole than the one which tried to link planetary rotation directly to a rotating celestial sphere.

The empirical IAU vehicle tries to project RA/Dec into the 24 hour framework which adds even more nonsense to an already contrived and toxic situation and far worse than any geocentric scheme of epicycles and equants -

" UT1 (or plain UT) is the modern equivalent of mean solar time, and is really an angle rather than time in the physics sense. Originally defined in terms of a point in the sky called "the fictitious mean Sun", UT1 is now defined through its relationship with Earth rotation angle (formerly through sidereal time)." IAU

http://www.iausofa.org/2015_0209_F/sofa/sofa_ts_f.pdf


This is all very well and good for somebody who understands both the language of timekeeping and the language of astronomy and how not to mix the two up but nobody else I know is really conversant with that language even though it is vaguely familiar to most people via the Lat/Long system.

There may be no stopping the unorganized rabble from deciding something really dumb next month as they are not astronomers in the first place however it takes only a little effort to fix the actual reference for timekeeping, what causes the event where Sirius skips an appearance by one day/rotation and thereby take into account the necessary orbital input of the Earth into the line-of-sight motion of the stars behind the central Sun.

I have to single out this wayward assertion for special attention as it comes from the same people who have organized a fiction in order to make a silly choice next month -

" UT1 (or plain UT) is the modern equivalent of mean solar time, and is really an angle rather than time in the physics sense. Originally defined in terms of a point in the sky called "the fictitious mean Sun", UT1 is now defined through its relationship with Earth rotation angle (formerly through sidereal time)." IAU "

http://www.iausofa.org/2015_0209_F/sofa/sofa_ts_f.pdf


Despite the blizzard of 'timekeeping' designations, the 24 hour day is a product of the average length of time it takes the Sun to cross an observer's meridian from one noon to the next within the calendar framework.

If instead of the hands of a watch sweeping across its face was used and a sand timer was substituted, each individual noon cycle would produce a different size mound of sand representing variations in the length of time for each noon cycle. If 30 of these mounds of sand representing 30 days were accumulated and divided equally, it would produce an average amount of sand close to an equivalent 24 hour day, the more natural days are used the more accurate the average becomes.

This rubbish from the empirical IAU about 'Universal Time' being a 'rotation angle' is merely the sound of thugs unable to appreciate what is involved in timekeeping, where it meshes closely with the daily and annual cycles of the Earth and how timekeeping actually developed using known references.

I quite understand that most here have absolutely no interest whatsoever in either timekeeping or astronomy and subsist on magnification equipment alone as 'astronomy'. It doesn't excuse those who make a living and try to push through fraudulent claims with no basis in observations and experience with special attention which links timekeeping to the planet's rotation via the Lat/Long system and not RA/Dec.

Picking up the theme of the last statement that the Latitude and Longitude system represents the planet's daily rotation via the 24 hour system and not the RA/Dec system, it remains to be explained how the correct systems fit inside planetary cycles from which they emerged.

Working towards a common purpose is a reward in itself so long as the endeavor elevates the human spirit rather than weighs it down. Although first appearances would suggest no great satisfaction from dealing with the nuts and bolts of timekeeping, it turns out to be a mischievous affair and a great deal of fun incorporating so many causes and effects between the motions of the Earth and terrestrial sciences, the structure of the solar system and the historical trajectory of discovery.

It also depends on where people are at in their lives in being neither a leader or a follower, neither a teacher nor student but rather simply enjoying what is in front of them as the Earth turns and moves through space in its journey around the Sun.

It is a shame that even with imaging from space that NASA couldn't get the inclination right insofar as the North pole is 23 1/2 degrees below the fully illuminated face of the Earth while the South pole is 23 1/2 degree North of that same face whenever each location is seen after the Equinox.

http://www.nesdis.noaa.gov/DSCOVR/


As long as the North/South polar latitudes maintain this position, then and only then can the daily rotation of the Earth be represented accurately.