equal at the equator?

On Nov 5, 5:08*pm, PD wrote:

My mistake. I had thought that declination of the sun from vertical
would produce a shortened time between sunrise and sunset, but this
appears to be wrong.

As I said, the opposite is in fact true, due to atmospheric effects
that cause sunrise and sunset when the sun is below the astronomical
horizon. See this: http://aa.usno.navy.mil/cgi-bin/aa_rstablew2.pl -
the effect is about 1 minute of variation.

Andrew Usher

Andrew Usher wrote:
On Nov 5, 5:08 pm, PD wrote:

My mistake. I had thought that declination of the sun from vertical
would produce a shortened time between sunrise and sunset, but this
appears to be wrong.

As I said, the opposite is in fact true, due to atmospheric effects
that cause sunrise and sunset when the sun is below the astronomical
horizon. See this: http://aa.usno.navy.mil/cgi-bin/aa_rstablew2.pl -
the effect is about 1 minute of variation.

Andrew Usher

Correct answer.

The standard definition of sunrise or sunset is when the apparent upper
limb of the sun is tangent to the ideal horizon. Conventionally this is
taken to mean that the zenith distance of the apparent sun is 90 degrees
50 minutes of arc.

It's those extra 50' which are the key to the problem. When you're
standing on the earth's equator, the sun's vertical speed is greater at
the equinoxes (when the sun is at 0 degrees declination, or on the
celestial equator) than at the solstices (when the sun is at +/-23
degrees declination). There's a factor of cos Dec in there. So the sun
takes longer to set at the solstices, and the days at the equator are
*shortest* at the equinoxes and *longest* at the solstices.

-- Bill Owen

On Nov 4, 5:40*pm, Mark-T wrote:
Is there such a thing as summer and winter solstice
at the equator?

Mark

The short answer is that summer/winter are hemispherical terms while
the solstice and equinox are global and orbital events
therefore,astronomically at least,summer/winter terms at the equator
are meaningless.By attempting to reference seasonal changes by way of
axial inclination to the Sun instead of taking a wider view of the
actual planetary dynamics behind the cause of the Equinox and
Solstice, these guys can't even explain why there is a rapid
transition to darkness or daylight due to rotational speeds at the
equator as opposed to longer twilights at higher latitudes and so long
as the Sun is visible over a year (not polar regions).

The ancient astronomers recognized that certain stars appeared and
disappeared over the course of a year, the stars of Orion for
instance,but because contemporaries,I cannot dare call them
astronomers at the moment,insist on giving influence to the motion of
constellations in stellar circumpolar motion you will never get a
straight answer or the one you get will be from a homocentrist,a
person who can't organize his thought around the Earth's planetary
dynamics.

On Nov 4, 7:03*pm, Sam Wormley wrote:
On 11/4/10 12:40 PM, Mark-T wrote:

Is there such a thing as summer and winter solstice
at the equator?

Mark

* *Solstices are not location specific.

A solstice and an equinox is a specific orbital event which is best
expressed as the relationship between the polar coordinates and the
circle of illumination in terms of the slow orbital turning to the
central Sun,it has nothing to do with 'tilt to the normal of the
orbital plane' or some other meaningless junk that you
homocentrists.If the reader imagines the polar daylight/darkness cycle
where 6 months of daylight is followed by 6 months of darkness due
solely to the orbital motion of the Earth as the polar coordinates
turn through 360 degrees to the central Sun hence the separate orbital
cycle and why we have solstices and equinoxes,mix in daily rotation
and it will explain why there is no summer/winter at the equator .

If you have trouble with the orbital component and why it is utterly
inappropriate to talk of declination of the Sun when discussing
equinoxes as events in the realm of planetary dynamics then the
observed time lapse footage of Uranus will put this matter to rest -

http://hubblesite.org/newscenter/arc...999/11/video/b

Another day giving doctorates an education they never had.

On 11/7/10 3:57 AM, oriel36 wrote:
On Nov 4, 7:03 pm, Sam wrote:
On 11/4/10 12:40 PM, Mark-T wrote:

Is there such a thing as summer and winter solstice
at the equator?

Mark

Solstices are not location specific.

A solstice and an equinox is a specific orbital event which is best
expressed as the relationship between the polar coordinates and the
circle of illumination in terms of the slow orbital turning to the
central Sun,it has nothing to do with 'tilt to the normal of the
orbital plane' or some other meaningless junk that you
homocentrists.If the reader imagines the polar daylight/darkness cycle
where 6 months of daylight is followed by 6 months of darkness due
solely to the orbital motion of the Earth as the polar coordinates
turn through 360 degrees to the central Sun hence the separate orbital
cycle and why we have solstices and equinoxes,mix in daily rotation
and it will explain why there is no summer/winter at the equator .

If you have trouble with the orbital component and why it is utterly
inappropriate to talk of declination of the Sun when discussing
equinoxes as events in the realm of planetary dynamics then the
observed time lapse footage of Uranus will put this matter to rest -

http://hubblesite.org/newscenter/arc...999/11/video/b

Another day giving doctorates an education they never had.


The times of equinoxes and solstices are defined to be when the
Sun's apparent ecliptic longitude λ_s is a multiple of 90°
-Explanatory Supplement to the Astronomical Almanac

More Background: Tropical Events: the solstices and equinoxes
http://www.thetropicalevents.com/

On 11/7/10 3:45 AM, oriel36 wrote:
On Nov 4, 5:40 pm, wrote:
Is there such a thing as summer and winter solstice
at the equator?

Mark

The short answer is that summer/winter are hemispherical terms while
the solstice and equinox are global and orbital events
therefore,astronomically at least,summer/winter terms at the equator
are meaningless.By attempting to reference seasonal changes by way of
axial inclination to the Sun instead of taking a wider view of the
actual planetary dynamics behind the cause of the Equinox and
Solstice, these guys can't even explain why there is a rapid
transition to darkness or daylight due to rotational speeds at the
equator as opposed to longer twilights at higher latitudes and so long
as the Sun is visible over a year (not polar regions).

The ancient astronomers recognized that certain stars appeared and
disappeared over the course of a year, the stars of Orion for
instance,but because contemporaries,I cannot dare call them
astronomers at the moment,insist on giving influence to the motion of
constellations in stellar circumpolar motion you will never get a
straight answer or the one you get will be from a homocentrist,a
person who can't organize his thought around the Earth's planetary
dynamics.




The times of equinoxes and solstices are defined to be when the
Sun's apparent ecliptic longitude λ_s is a multiple of 90°
-Explanatory Supplement to the Astronomical Almanac

More Background: Tropical Events: the solstices and equinoxes
http://www.thetropicalevents.com/

On Nov 7, 1:09Â*pm, Sam Wormley wrote:
On 11/7/10 3:57 AM, oriel36 wrote:









On Nov 4, 7:03 pm, Sam Â*wrote:
On 11/4/10 12:40 PM, Mark-T wrote:

Is there such a thing as summer and winter solstice
at the equator?

Mark

Â* Â* Solstices are not location specific.

A solstice and an equinox is a specific orbital event which is best
expressed as the relationship between the polar coordinates and the
circle of illumination in terms of the slow orbital turning to the
central Sun,it has nothing to do with 'tilt to the normal of the
orbital plane' or some other meaningless junk that you
homocentrists.If the reader imagines the polar daylight/darkness cycle
where 6 months of daylight is followed by 6 months of darkness due
solely to the orbital motion of the Earth as the polar coordinates
turn through 360 degrees to the central Sun hence the separate orbital
cycle and why we have solstices and equinoxes,mix in daily rotation
and it will explain why there is no summer/winter at the equator .

If you have trouble with the orbital component and why it is utterly
inappropriate to talk of declination of the Sun when discussing
equinoxes as events in the realm of planetary dynamics then the
observed time lapse footage of Uranus will put this matter to rest -

http://hubblesite.org/newscenter/arc...999/11/video/b

Another day giving doctorates an education they never had.

Â* Â*The times of equinoxes and solstices are defined to be when the
Â* Â*Sun's apparent ecliptic longitude λ_s is a multiple of 90°
Â* Â* Â* Â* -Explanatory Supplement to the Astronomical Almanac


I have been looking at how most here operate when a simple question
such as this one is asked,they blitz the reader with worthless time
acronyms like Stockton or like you,make no attempt whatsoever to
frame the orbital events of solstices and equinoxes in terms of
planetary dynamics.

" He [Copernicus] thus speaks of “sunrise� and “sunset,� of the
“rising and setting� of the stars, of changes in the obliquity of the
ecliptic and of variations in the equinoctial points, of the mean
motion and variations in motion of the sun, and so on. All these
things really relate to the earth, but since we are fixed to the earth
and consequently share in its every motion, we cannot discover them in
the earth directly, and are obliged to refer them to the heavenly
bodies in which they make their appearance to us. Hence we name them
as if they took place where they appear to us to take place; and from
this one may see how natural it is to accommodate things to our
customary way of seeing them." Galileo

Observationally,since we are no longer fixed to the Earth we can see
the motions of the Earth from space and conclude that as the Earth
moves around the Sun ,the polar coordinates can be seen to pass
through the circle of illumination at the equinoxes thereby
explaining the polar daylight/darkness cycle in terms of an orbital
signature .

With not enough sense to remove yourselves from the timekeeping system
long enough to look at the raw daily and orbital dynamics, and
especially the terrestrial effects,you launch into your 'tilt to the
normal of the orbital plane' thingy you are always on about.The
Equinox occurs when the polar coordinates split the circle of
illumination and the solstices are when the orbital turning of the
Earth brings the polar coordinates to a maximum distance to the circle
of illumination,it is not rocket science and if you need an imitation
analogy then just use a broom to substitute for daily rotation and
walk around an object to imitate the orbital behavior of the Earth.

The poet Yeats said that "too much sacrifice can turn the heart to
stone" but while this may be accurate for some,for others it makes a
person love the achievements of the old astronomers and ability of the
young to marvel at things all the more,the disdain is for the mediocre
middle who,like you,have their own agenda.





Â* Â*More Background: Tropical Events: the solstices and equinoxes
Â* Â* Â*http://www.thetropicalevents.com/

On 11/7/10 8:27 AM, oriel36 wrote:


I have been looking at how most here operate when a simple question
such as this one is asked,they blitz the reader with worthless time
acronyms like Stockton or like you,make no attempt whatsoever to
frame the orbital events of solstices and equinoxes in terms of
planetary dynamics.

" He [Copernicus] thus speaks of “sunrise� and “sunset,� of the
“rising and setting� of the stars, of changes in the obliquity of the
ecliptic and of variations in the equinoctial points, of the mean
motion and variations in motion of the sun, and so on. All these
things really relate to the earth, but since we are fixed to the earth
and consequently share in its every motion, we cannot discover them in
the earth directly, and are obliged to refer them to the heavenly
bodies in which they make their appearance to us. Hence we name them
as if they took place where they appear to us to take place; and from
this one may see how natural it is to accommodate things to our
customary way of seeing them." Galileo

Observationally,since we are no longer fixed to the Earth we can see
the motions of the Earth from space and conclude that as the Earth
moves around the Sun ,the polar coordinates can be seen to pass
through the circle of illumination at the equinoxes thereby
explaining the polar daylight/darkness cycle in terms of an orbital
signature .

With not enough sense to remove yourselves from the timekeeping system
long enough to look at the raw daily and orbital dynamics, and
especially the terrestrial effects,you launch into your 'tilt to the
normal of the orbital plane' thingy you are always on about.The
Equinox occurs when the polar coordinates split the circle of
illumination and the solstices are when the orbital turning of the
Earth brings the polar coordinates to a maximum distance to the circle
of illumination,it is not rocket science and if you need an imitation
analogy then just use a broom to substitute for daily rotation and
walk around an object to imitate the orbital behavior of the Earth.

The poet Yeats said that "too much sacrifice can turn the heart to
stone" but while this may be accurate for some,for others it makes a
person love the achievements of the old astronomers and ability of the
young to marvel at things all the more,the disdain is for the mediocre
middle who,like you,have their own agenda.


Nevertheless, the times of equinoxes and solstices are DEFINED to
be when the Sun's apparent ecliptic longitude λ_s is a multiple of 90°
-Explanatory Supplement to the Astronomical Almanac

On Nov 7, 2:31Â*pm, Sam Wormley wrote:
On 11/7/10 8:27 AM, oriel36 wrote:











I have been looking at how most here operate when a simple question
such as this one is asked,they blitz the reader with worthless time
acronyms Â*like Stockton or like you,make no attempt whatsoever to
frame the orbital events of solstices and equinoxes in terms of
planetary dynamics.

" He [Copernicus] thus speaks of “sunrise� and “sunset,� of the
“rising and setting� of the stars, of changes in the obliquity of the
ecliptic and of variations in the equinoctial points, of the mean
motion and variations in motion of the sun, and so on. All these
things really relate to the earth, but since we are fixed to the earth
and consequently share in its every motion, we cannot discover them in
the earth directly, and are obliged to refer them to the heavenly
bodies in which they make their appearance to us. Hence we name them
as if they took place where they appear to us to take place; and from
this one may see how natural it is to accommodate things to our
customary way of seeing them." Galileo

Observationally,since we are no longer fixed to the Earth we can see
the motions of the Earth from space and conclude that as the Earth
moves around the Sun ,the polar coordinates can be seen to pass
through the Â*circle of illumination at the equinoxes thereby
explaining the polar daylight/darkness cycle in terms of an orbital
signature .

With not enough sense to remove yourselves from the timekeeping system
long enough to look at the raw daily and orbital dynamics, and
especially the terrestrial effects,you launch into your 'tilt to the
normal of the orbital plane' thingy you are always on about.The
Equinox occurs when the polar coordinates split the circle of
illumination and the solstices are when the orbital turning of the
Earth brings the polar coordinates to a maximum distance to the circle
of illumination,it is not rocket science and if you need an imitation
analogy then just use a broom to substitute for daily rotation and
walk around an object to imitate the orbital behavior of the Earth.

The poet Yeats said that "too much sacrifice can turn the heart to
stone" but while this may be accurate for some,for others it makes a
person love the achievements of the old astronomers and ability of the
young to marvel at things all the more,the disdain is for the mediocre
middle who,like you,have their own agenda.

Â* Â*Nevertheless, the times of equinoxes and solstices are DEFINED to
Â* Â*be when the Sun's apparent ecliptic longitude λ_s is a multiple of 90°
Â* Â* Â* Â* -Explanatory Supplement to the Astronomical Almanac

Is this all you or anyone else has !.The answer to the question is
that solstice and equinox are both orbital terms while summer and
winter are hemispherical terms and with a little effort,you work on
daily and orbital dynamics first to get a clear enough global picture
and then work on hemispherical conditions like summer and winter after
that.

None of you like astronomy,you can't tell how long it takes the Earth
to turn once nor how many rotations in a year even though all you need
to do is count,you won't discuss the orbital daylight/darkness cycle
even it takes only a phone call to the South pole to affirm that they
will experience daylight for the next 5 months or the actual orbital
cause of it.I see astronomy completely dilapidated and no attempt to
rebuild it with modern imaging but how many people who give themselves
the title of astronomer will go to their offices tomorrow and actually
work to make this a better place through an honest attempt to match
cause and effect and specifically planetary dynamics with terrestrial
effects.

On 11/7/10 10:30 AM, oriel36 wrote:
None of you like astronomy,you can't tell how long it takes the Earth
to turn once nor how many rotations in a year even though all you need
to do is count,you won't discuss the orbital daylight/darkness cycle
even it takes only a phone call to the South pole to affirm that they
will experience daylight for the next 5 months or the actual orbital
cause of it.

The angular velocity of the earth is precisely measured, Gerald. The
angular velocity is 0.72921158553 × 10^-4 rad/s, which comes out to
be 86164.0905 seconds for a 2π (360°) rotation.

Click on this google link for the calculation:
http://www.google.com/search?q=360+d...%29+in+seconds