earth's tilt

When and how did astronomers determine that the earth's axis
tilts from the ecliptic, and its value?

--
Rich

RichD wrote:
When and how did astronomers determine that the earth's axis
tilts from the ecliptic, and its value?


I guess the answer depends on who you ask.

http://search.yahoo.com/search;_ylt=...8&fr=yfp-t-701


Just like Galileo is often credited for claiming the earth went around the
sun.
His research was based on Copernicus's work, and who knows where Copernicus
got the idea.

RichD:
When and how did astronomers determine that the earth's axis
tilts from the ecliptic, and its value?

Bast:
I guess the answer depends on who you ask.

Indeed, it does. My dad was first a ship's navigator and then a pilot
in his young years. It was he who first told me about the stars. I
remember him asking me when I was not very far along in elementary
school "Have they taught you yet that Columbus proved that the Earth is
round?" "No? Well, they will. Don't make a fuss over it, but they're
wrong. Eratosthenes, who lived hundreds of years B.C., knew the Earth
was round and he even made an accurate measurement of its
circumference. So educated men have known for more than 2,000 years
that the Earth is round."

I didn't make a fuss over it when the time came in geography class, but
I did tell the teacher to check out Eratosthenes in the encyclopedia.
(That was a set of about 30 books printed on paper in those days.)

I don't have time to do the searching at the moment, but I have to
think that ancient natural philosophers, whether in Greece or Persia or
China or parts unknown, knew the extent of the Earth's axial tilt. Just
about anyone who gave it some thought could figure it out, even if they
believed in a geocentric Universe. Otherwise they would have to think
that the Universe wobbled as it orbited the Earth. That could be
accounted for, but there were people who were smarter than that.

--
I agree with almost everything that you have said and almost everything that
you will say in your entire life.

usenet *at* davidillig dawt cawm

"Davoud" wrote in message ...
RichD:
When and how did astronomers determine that the earth's axis
tilts from the ecliptic, and its value?

Bast:
I guess the answer depends on who you ask.

Indeed, it does. My dad was first a ship's navigator and then a pilot
in his young years. It was he who first told me about the stars. I
remember him asking me when I was not very far along in elementary
school "Have they taught you yet that Columbus proved that the Earth is
round?" "No? Well, they will. Don't make a fuss over it, but they're
wrong. Eratosthenes, who lived hundreds of years B.C., knew the Earth
was round and he even made an accurate measurement of its
circumference. So educated men have known for more than 2,000 years
that the Earth is round."

I didn't make a fuss over it when the time came in geography class, but
I did tell the teacher to check out Eratosthenes in the encyclopedia.
(That was a set of about 30 books printed on paper in those days.)

I don't have time to do the searching at the moment, but I have to
think that ancient natural philosophers, whether in Greece or Persia or
China or parts unknown, knew the extent of the Earth's axial tilt. Just
about anyone who gave it some thought could figure it out, even if they
believed in a geocentric Universe. Otherwise they would have to think
that the Universe wobbled as it orbited the Earth. That could be
accounted for, but there were people who were smarter than that.


-

Not only did educated men know, but they also had built a computer
to model it.
http://en.wikipedia.org/wiki/Antikythera_mechanism

Ancient Greek technology was destroyed by Roman barbarians and not
duplicated until Victorian England, long after Galileo Galilei challenged
the Roman Barbarian Church.

- This message is brought to you from the keyboard of
Lord Androcles, Zeroth Earl of Medway

In sci.astro.amateur message , Thu, 20
Sep 2012 22:11:43, Davoud posted:


I don't have time to do the searching at the moment, but I have to
think that ancient natural philosophers, whether in Greece or Persia or
China or parts unknown, knew the extent of the Earth's axial tilt.

http://en.wikipedia.org/wiki/Earth%27s_Axis#History.

--
(c) John Stockton, nr London, UK. Mail via homepage. Turnpike v6.05 MIME.
Web http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms and links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

"Dr J R Stockton" wrote in message nvalid...
In sci.astro.amateur message , Thu, 20
Sep 2012 22:11:43, Davoud posted:


I don't have time to do the searching at the moment, but I have to
think that ancient natural philosophers, whether in Greece or Persia or
China or parts unknown, knew the extent of the Earth's axial tilt.

http://en.wikipedia.org/wiki/Earth%27s_Axis#History.


“Pytheas of Marseilles measured the shadow of a gnomon at the summer solstice�
What does the angle of the top of this standing stone in Scotland signify to
you, Stockton?
http://images.travelpod.com/tw_slide...ey-islands.jpg
A gnomon, perhaps?
http://en.wikipedia.org/wiki/Gnomon

The way to measure the angle of the Earth’s tilt is with a shadow,
and standing stones date to 3500 BCE. You went too far looking
to China.

-- This message is brought to you from the keyboard of
Lord Androcles, Zeroth Earl of Medway

On Sep 22, 8:02*pm, Dr J R Stockton
wrote:
In sci.astro.amateur message , Thu, 20
Sep 2012 22:11:43, Davoud posted:



I don't have time to do the searching at the moment, but I have to
think that ancient natural philosophers, whether in Greece or Persia or
China or parts unknown, knew the extent of the Earth's axial tilt.

http://en.wikipedia.org/wiki/Earth%27s_Axis#History.


I look at how they mangle the straightforward reasoning which connects
planetary shape with the motion and evolution of the surface crust
long after I proposed differential rotation as the key mechanism for
these planetary features.The uneven rotational gradient of the fluid
interior requires dropping the idea of the Earth as a celestial
gyroscope and picking up observations of celestial objects with
exposed rotating fluid compositions which display differential
rotation. The polar coordinates don't act like a gyroscope nor 'tilt'
towards and away from the Sun but rather are carried around in a
circle to the central Sun by the separate orbital motion of the
Earth,this leaves the researcher free to work with daily rotation and
the fluid interior rather than being too concerned about a fixed axis
- horses for courses in other words.

For an era so concerned with climate,it is amazing that they can't
describe the Earth's climate in planetary terms,in our planet's
case,it is largely equatorial as opposed to the polar climate of
Uranus by based on the angular distance between the the daily
rotational axis and the ecliptic axis.The Wiki article is more of the
same -

"The Earth's axis remains tilted in the same direction with reference
to the background stars throughout a year (throughout its entire
orbit). This means that one pole (and the associated hemisphere of the
Earth) will be directed away from the Sun at one side of the orbit,
and half an orbit later (half a year later) this pole will be directed
towards the Sun. This is the cause of the Earth's seasons."

http://en.wikipedia.org/wiki/Earth%27s_Axis#History

The cause of daylight/darkness asymmetries with greater fluctuations
towards the polar coordinates is due to the changing relationship of
rotational orientation of the planet to the circle of illumination.It
is so clearly demonstrated by the images of Uranus as the hemispheres
experience extreme fluctuations in daylight/darkness across large
areas of the planet that a thinking person can't but see that the old
idea of axial precession is an obstacle to recognizing the changing
orientation of the rotational axis to the central Sun.

I see these awkward 'tilted' explanations when it takes only a simple
imitation analogy to introduce another axis around which the polar
coordinates turn to the central Sun, a broom handle representing axial
'tilt' and the line of the body walking/orbiting a central object
representing an ecliptic axis goes a long way to accounting for the
observations of Uranus as the broom handle remains fixed to an
external point at all times as a person walks/orbits the object yet
the tilt of the broom will change to the central object/Sun as it
moves in a circle.

I wish somebody else would raise themselves to a higher standard,after
all,when you have all these guys running around announcing that the
sky is falling with climate,the same people have yet to replace the
old 'no tilt/no seasons' ideology with the new approach where a planet
falls between an equatorial and polar climate due to its inclination.






--
*(c) John Stockton, nr London, UK. *Mail via homepage. *Turnpike v6..05 *MIME.
* Web *http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms and links;
* Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
*No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

On Sep 23, 3:12*am, oriel36 wrote:
On Sep 22, 8:02*pm, Dr J R Stockton

wrote:
In sci.astro.amateur message , Thu, 20
Sep 2012 22:11:43, Davoud posted:

I don't have time to do the searching at the moment, but I have to
think that ancient natural philosophers, whether in Greece or Persia or
China or parts unknown, knew the extent of the Earth's axial tilt.

http://en.wikipedia.org/wiki/Earth%27s_Axis#History.

I look at how they mangle the straightforward reasoning which connects
planetary shape with the motion and evolution of the surface crust
long after I proposed differential rotation as the key mechanism for
these planetary features.The uneven rotational gradient of the fluid
interior requires dropping the idea of the Earth as a celestial
gyroscope *and picking up observations of celestial objects with
exposed rotating fluid compositions which display differential
rotation. The polar coordinates don't act like a gyroscope nor 'tilt'
towards and away from the Sun but rather are carried around in a
circle to the central Sun by the separate orbital motion of the
Earth,this leaves the researcher free to work with daily rotation and
the fluid interior rather than being too concerned about a fixed axis
- horses for courses in other words.

For an era so concerned with climate,it is amazing that they can't
describe the Earth's climate in planetary terms,in our planet's
case,it is largely equatorial as opposed to the polar climate of
Uranus by based on the angular distance between the the daily
rotational axis and the ecliptic axis.The Wiki article is more of the
same -

"The Earth's axis remains tilted in the same direction with reference
to the background stars throughout a year (throughout its entire
orbit). This means that one pole (and the associated hemisphere of the
Earth) will be directed away from the Sun at one side of the orbit,
and half an orbit later (half a year later) this pole will be directed
towards the Sun. This is the cause of the Earth's seasons."

http://en.wikipedia.org/wiki/Earth%27s_Axis#History

The cause of daylight/darkness asymmetries with greater fluctuations
towards the polar coordinates is due to the changing relationship of
rotational orientation of the planet to the circle of illumination.It
is so clearly demonstrated by the images of Uranus as the hemispheres
experience extreme fluctuations in daylight/darkness across large
areas *of the planet that a thinking person can't but see that the old
idea of axial precession is an obstacle to recognizing the changing
orientation of the rotational axis to the central Sun.

I see these awkward 'tilted' explanations when it takes only a simple
imitation analogy to introduce another axis around which the polar
coordinates turn to the central Sun, a broom handle representing axial
'tilt' and the line of the body walking/orbiting a central object
representing an ecliptic axis goes a long way to accounting for the
observations of Uranus as the broom handle remains fixed to an
external point at all times as a person walks/orbits the object yet
the tilt of the broom will change to the central object/Sun as it
moves in a circle.

I wish somebody else would raise themselves to a higher standard,after
all,when you have all these guys running around announcing that the
sky is falling with climate,the same people have yet to replace the
old 'no tilt/no seasons' ideology with the new approach where a planet
falls between an equatorial and polar climate due to its inclination.



--
*(c) John Stockton, nr London, UK. *Mail via homepage. *Turnpike v6.05 *MIME.
* Web *http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms and links;
* Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
*No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.- Hide quoted text -

- Show quoted text -

Moon keeps tilt from wobbling.and with wobbling there would be no
humankind. TeBet

On 21 Sep, 03:47, "Bast" wrote:
RichD wrote:
When and how did astronomers determine that the earth's axis
tilts from the ecliptic, and its value?

I guess the answer depends on who you ask.

http://search.yahoo.com/search;_ylt=...Ed5ebvZx4?p=Wh...

Just like Galileo is often credited for claiming the earth went around the
sun.
His research was based on Copernicus's work, and who knows where Copernicus
got the idea.

He used data collected by Tycho Brahe

JT wrote:
On 21 Sep, 03:47, "Bast" wrote:
RichD wrote:
When and how did astronomers determine that the earth's axis
tilts from the ecliptic, and its value?

I guess the answer depends on who you ask.

http://search.yahoo.com/search;_ylt=...Ed5ebvZx4?p=Wh...

Just like Galileo is often credited for claiming the earth went around
the sun.
His research was based on Copernicus's work, and who knows where
Copernicus got the idea.

He used data collected by Tycho Brahe



That would be a neat trick considering, I believe, Tycho Brache was born
after Copernicus died.