Independence Day

" O say, can you see, by the dawn's early light, What so proudly we hail'd at the twilight's last gleaming?"

This much loved national line in a verse has now an international counterpart -

http://www.usap.gov/videoclipsandmaps/spwebcam.cfm

The great orbital twilight as the Sun is now out of sight for the next 5 months at the South pole draws its recognition from the daily terms and all the events bounded within dawn and twilight as the Earth turns once daily.

When this is all said and done, people will have two cycles and two rotations in splendid isolation to look at and then to combine them in making sense of experience of the day and the seasons.

oriel36 wrote:
" O say, can you see, by the dawn's early light, What so proudly we
hail'd at the twilight's last gleaming?"

This much loved national line in a verse has now an international counterpart -

http://www.usap.gov/videoclipsandmaps/spwebcam.cfm

The great orbital twilight as the Sun is now out of sight for the next 5
months at the South pole draws its recognition from the daily terms and
all the events bounded within dawn and twilight as the Earth turns once daily.

When this is all said and done, people will have two cycles and two
rotations in splendid isolation to look at and then to combine them in
making sense of experience of the day and the seasons.






http://www.jpl.nasa.gov/news/news.php?feature=6332

'Earth's Rotation'
" The Earth rotates on its axis relative to the sun every 24.0 hours mean solar time, with an inclination of 23.45 degrees from the plane of its orbit around the sun. Mean solar time represents an average of the variations caused by Earth's non-circular orbit. Its rotation relative to "fixed" stars (sidereal time) is 3 minutes 56.55 seconds shorter than the mean solar day, the equivalent of one solar day per year." NASA

https://solarsystem.nasa.gov/basics/bsf2-1.php

Intrinsic to the anthem of the USA are the references to dawn and twilight representing the appearance of the Sun followed by the stars each 24 hours. This system begins from a set of references with their origins in antiquity and predate clocks and the Equation of Time which equalizes out the variations in all complete noon cycles to a 24 hour average.

The awful assertion that the homocentric reference of celestial sphere rotation equates to the Earth's rotation in 23 hours 56 minutes 04 seconds is the central pillar in that horror passed on from one generation to the next until it arrives at JPL in this century.

Not only the boundary of dawn and twilight which divides the appearance of the Sun from the stars each day rescues astronomy from celestial sphere indoctrination but also the polar dawn and twilight which introduces a separate surface rotation as something new to work on.

I am returning a kindness.

There is a clear distinction between rotation/revolution and orbital motion so without a definite partitioning of terms,the empiricists have created havoc. The JPL description is wrong insofar as the Earth revolves/rotates around its own center while it orbits the Sun representing a separate object and center.

'Rotation and Revolution'
"Rotation" refers to an object's spinning motion about its own axis. "Revolution" refers the object's orbital motion around another object. For example, Earth rotates on its own axis, producing the 24-hour day. Earth revolves about the Sun, producing the 365-day year. A satellite revolves around a planet."

https://solarsystem.nasa.gov/basics/bsf2-1.php


The moon doesn't revolve around the Earth, it orbits the planet so even to this day the empiricists believe the moon revolves/ rotates because it was wrongly used in Kepler's Somnium and ultimately seriously misused by Newton -

https://books.google.ie/books?id=OdC...ge&q&f=fa lse

Reasonable people could spot where the notion of a spinning moon comes from or rather, the inability to distinguish the orbital behavior of the moon around the Earth as opposed to the Earth around the Sun.

Btw, Kepler and many others who applied speculative notions as to why smaller objects orbit larger objects around the larger object's rotational Equator was lost in the late 17th century when experimental theorists got involved in astronomy.

"The Sun and the Earth rotate on their own axes...The purpose of this
motion is to confer motion on the planets located around them;on the
six primary planets in the case of the Sun,and on the moon in the case
of the Earth.On the other hand the moon does not rotate on the axis of
its own body,as its spots prove " Kepler

On Saturday, April 16, 2016 at 12:06:29 AM UTC-7, oriel36 wrote:

There is a clear distinction between rotation/revolution and orbital motion...

'Rotation and Revolution'
"Rotation" refers to an object's spinning motion about its own axis. "Revolution" refers the object's orbital motion around another object. For example, Earth rotates on its own axis, producing the 24-hour day. Earth revolves about the Sun, producing the 365-day year. A satellite revolves around a planet."

Indeed, this all correct... but... read this...

https://en.wikipedia.org/wiki/Moon

"The Moon (in Latin: Luna, in Greek: Σελήνη Selene) is Earth's only natural satellite. It is one of the largest natural satellites in the Solar System..."

As you have noted, above, "A satellite revolves around a planet.", and clearly the moon IS a satellite. A natural satellite. Of course, every moon in the solar system can also be correctly called a satellite. Apparently you have become confused because of the hundreds and hundreds of artificial satellites that ring the Earth are more colloquially called just plain 'satellites', without many people bothering to use the adjective 'artificial'.

The moon definitely revolves around the Earth, just as the other moons revolve around their own planets.

On Saturday, April 16, 2016 at 8:43:09 PM UTC+1, palsing wrote:
On Saturday, April 16, 2016 at 12:06:29 AM UTC-7, oriel36 wrote:

There is a clear distinction between rotation/revolution and orbital motion...

'Rotation and Revolution'
"Rotation" refers to an object's spinning motion about its own axis. "Revolution" refers the object's orbital motion around another object. For example, Earth rotates on its own axis, producing the 24-hour day. Earth revolves about the Sun, producing the 365-day year. A satellite revolves around a planet."

Indeed, this all correct... but... read this...

https://en.wikipedia.org/wiki/Moon

"The Moon (in Latin: Luna, in Greek: Σελήνη Selene) is Earth's only natural satellite. It is one of the largest natural satellites in the Solar System..."

As you have noted, above, "A satellite revolves around a planet.", and clearly the moon IS a satellite. A natural satellite. Of course, every moon in the solar system can also be correctly called a satellite. Apparently you have become confused because of the hundreds and hundreds of artificial satellites that ring the Earth are more colloquially called just plain 'satellites', without many people bothering to use the adjective 'artificial'.

The moon definitely revolves around the Earth, just as the other moons revolve around their own planets.

The Earth revolves/rotates around its own center in two different ways while orbiting the Sun whereas the moon orbits the Earth alone hence the near side and the far side of the lunar surface with one side constantly facing the Earth.

https://en.wikipedia.org/wiki/Far_si...ransitfull.gif

The Earth's orbital motion produces an altogether different surface rotation than daily rotation where the poles will be seen to turn in a complete circle to the central Sun with the unique characteristic that this surface rotation responds to variations in orbital speed hence the variations in length of the noon cycle when combined with constant daily rotation.

I am not among boys as children grow into adults and take on adult responsibilities, some of which are a joy to behold so it is not really the common sense judgments which acknowledges motions as they actually exist along with their effects but rather how to deal with people who have forced themselves to believe two separate rotations within daily rotation, one to the Sun and the other to the stars.

There is a growing sorrow that there may be nobody with a love of the planetary motions they participate in ,after all, what can be more gorgeous than a sunset including the polar sunset you see in these images -

http://www.usap.gov/videoclipsandmaps/spwebcam.cfm

The bright stars will come into view at the South pole soon enough and with it closes out the last line of the verse with a more planetary and international meaning as it ends with a question and not a statement -

"O say does that star-spangled banner yet wave
O'er the land of the free and the home of the brave?"

Revisiting the JPL site once more -

"Because of the precession of the poles over 26,000 years, all the stars, and other celestial objects, appear to shift west to east at the rate of .014 degree each year (360 degrees in 26,000 years). This apparent motion is the main reason for astronomers as well as spacecraft operators to refer to a common epoch such as J2000.0." NASA

The core timekeeping framework is based on a specific event, in contemporary terms, the star Sirius drifts back in behind the Sun with each 365 day/rotation cycle so that it skips a first appearance by one day and rotation after the fourth 365 day cycle. This core framework makes the 24 hour day system and the Lat/Long system possible and also defines the proportion of rotations to an orbital circuit to close to 365 1/4 rotations per circuit but not exactly so and that is where the Precession of the Equinoxes comes in.

It needs a very nimble mind not to mix up observations made using timekeeping averages within the calendar framework and the core observations which actually set up human timekeeping.

If all people want to do is identify celestial objects using a celestial sphere/calendar framework using magnification equipment then fine but it has awful consequences for the relationship between planetary dynamics and terrestrial sciences.

http://calgary.rasc.ca/images/radec_...sion_lines.gif


As the Earth makes a circuit of the Sun the stars existing along or close to the orbital plane are obscured by the central Sun and its glare . This is absolutely crucial as the apparent motion of the stars is solely a result of the Earth's orbital motion and therefore loses all connection to RA/Dec -

https://www.youtube.com/watch?v=MdFrE7hWj0A

https://www.youtube.com/watch?v=eeQwYrfmvoQ


The observed Precession of the Equinoxes is from the same source as the reasons that Sirius skips a first appearance by one rotation after 4 cycles of 365 rotations. The reason this has been ignored up to now is that the geocentric system used an alternative motion of the Sun through the Zodiac and this was retained by the first heliocentric astronomers.For me it is as clear as day but may not be so for others who do not realize the tremendous leakage of information that results from proposing axial precession as the cause of the observed drift in the stars each year.

On Sunday, April 17, 2016 at 8:31:57 AM UTC+1, oriel36 wrote:
The observed Precession of the Equinoxes is from the same source as the reasons that Sirius skips a first appearance by one rotation after 4 cycles of 365 rotations.

Progress! You said "observed precession of the Equinoxes"! Up to now you have been denying that Precession of the Equinoxes is a real thing.

But no, it is not from that source. Today, the winter Solstice happens near perihelion (Jan 4 next year). In 13,000 years or so, it will happen near aphelion in July. This happens even if the calendar year is kept exactly in step with the seasons via leap days, which correct for the fact that the Solstice to Solstice year is not an even number of days long. Precession is a different and much slower effect.

On Tuesday, April 19, 2016 at 6:23:14 AM UTC+1, wrote:
On Sunday, April 17, 2016 at 8:31:57 AM UTC+1, oriel36 wrote:
The observed Precession of the Equinoxes is from the same source as the reasons that Sirius skips a first appearance by one rotation after 4 cycles of 365 rotations.

Progress! You said "observed precession of the Equinoxes"! Up to now you have been denying that Precession of the Equinoxes is a real thing.


The drift in position of the stars relative to the Sun known as the Precession of the Equinoxes is from the same source as the drift of Sirius by one day after every 4th year when the year is based on 365 days/rotations. From the first annual appearance of Sirius to the next took 365 rotations however the astronomers in antiquity recognized that Sirius skipped an appearance by 1 day after the fourth cycle which in contemporary dynamical terms represents a slow drift backwards of Sirius into the glare of the central Sun so what the leap day rotation does is keep the number of days/ rotations from drifting away from the orbital points of the Solstices and Equinoxes.

It is why the ancient Newgrange,Knowth and Stonehenge monuments still keep their alignments to the Solstices after 5200 years and 4500 years hence 'axial precession' as a dynamic is a non starter. What does work is that the proportion of rotations to orbital circuits is not exactly 365 1/4 rotations for one circuit so that there is an additional drift in the position of the stars known as the Precession of the Equinoxes. Of course empiricists insist that there are 366 1/4 rotations per orbital circuit which makes discussion of the intricate details next to impossible.


But no, it is not from that source. Today, the winter Solstice happens near perihelion (Jan 4 next year). In 13,000 years or so, it will happen near aphelion in July.

Using the calendar framework, the Winter Solstice happens on or around December 21st or June 21st depending on which side of the Equator is being considered. As the Newgrange monument is only a short drive from where I live I take great satisfaction in recognizing that when the Sun shines through a roofbox at dawn on the Solstice this year it was also lighting up a central chamber at the same time 5200 years ago.

http://www.knowth.com/winter-solstic...stice-2003.jpg











This happens even if the calendar year is kept exactly in step with the seasons via leap days, which correct for the fact that the Solstice to Solstice year is not an even number of days long. Precession is a different and much slower effect.

Copernicus faced an enormous difficulty in trying to promote the daily and orbital motions of the Earth while maintaining the working geocentric framework based on the annual motion of the Sun through the Zodiac on which the Precession of the Equinoxes is based. He originally got it right in 1514 by describing the motion of the polar points in a circle to the central Sun and parallel to the orbital plane but shifted his arguments in De Revolutionibus to account for the Precession of the Equinoxes instead -

"The third is the motion in declination. For, the axis of the daily rotation is not parallel to the Grand Orb's axis, but is inclined [to it at an angle that intercepts] a portion of a circumference, in our time about 23 1/2°. Therefore, while the earth's center always remains in the plane of the ecliptic, that is, in the circumference of a circle of the Grand Orb, the earth's poles rotate, both of them describing small circles about centers [lying on a line that moves] parallel to the Grand Orb's axis" Copernicus

http://copernicus.torun.pl/en/archiv...=transkrypcja&


It is not exactly if people can't stand the heat then they stay out of the kitchen as if they are required to go through astronomical history and the various technical strands , as far as I am concerned once they recognize the planet's two types of day/night cycles with two types of sunrises/sunsets with specific attention to the polar day/night cycle they are half way to the new perspective.

The star spangled banner does wave over a point on the Earth surface that sees only one sunrise each year hence the title of this thread -

http://eoimages.gsfc.nasa.gov/images...008265_lrg.jpg