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kajlina
Posted: Sun Jan 28, 2007 6:18 am
Guest
The period of rotation of Venus is 243 days while its period of
revolution is 225 days.
1.One day on Venus amounts to how many days on Earth?
2. If Venus's direction of rotation was the same as its direction of
revolution, then one day on Venus amounts to how many days on Earth?

I think both answers are 243 days. I suppose whatever the direction of
rotation is, the period of rotation doesn't change. Am I correct?
Brian Tung
Posted: Sun Jan 28, 2007 7:04 am
Guest
kajlina wrote:
Quote:
The period of rotation of Venus is 243 days while its period of
revolution is 225 days.
1. One day on Venus amounts to how many days on Earth?
2. If Venus's direction of rotation was the same as its direction of
revolution, then one day on Venus amounts to how many days on Earth?

Shouldn't homework problems be done at home?

Approach: If Venus didn't orbit the Sun, but rather stayed in one place
at all times, how long would the Venusian day be? From that answer, how
much of a circle would the Sun appear to make in one Earth day?

On the other hand, if Venus didn't rotate, but rather revolved around it
always facing the same direction (with respect to the stars), how long
would the Venusian day be? From that answer, how much of a circle would
the Sun appear to make in one Earth day?

In part 1, you either subtract one of these answers from the other, or
add one to the other, to find out how much of a circle the Sun appears
to make in one Earth day. Which is it? Then you can figure out how
many Earth days it takes the Sun to appear to make an entire circle.

In part 2, again, do you add or subtract? Why?

--
Brian Tung <brian@isi.edu>
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
oriel36
Posted: Sun Jan 28, 2007 8:10 am
Joined: 31 May 2004 Posts: 942
Would you like to see how the old astronomers figured out how long it
takes the other planets to complete an annual orbit by using the
annual motions of the Earth ?.

http://mitpress.mit.edu/journals/pdf/POSC_13_1_74_0.pdf

If you turn to page 86 you will see how astronomers plotted the motion
of Mars against the stellar background in terms of the stellar
background broken into constellational divisions.

You then compare the orbital cycle of Earth with that of Mars by
taking note of how many times the Earth overtakes in proportion to
Mars,in the words of Kepler himself -

"Copernicus, by attributing a single annual motion to the earth,
entirely rids the planets of these extremely intricate coils [spiris],
leading the individual planets into their respective orbits
[orbitas],quite bare and very nearly circular. In the period of time
shown in the diagram, Mars traverses one and the same orbit as many
times as the 'garlands' [corollas] you see looped towards the centre,
with one extra, making nine times, while at the same time the repeats
its circle sixteen times "

Using this procedure for Venus,Kepler could then affirm through his
10th argument for heliocentricity why the Earth's motion between Venus
and Mars replaced the Ptolemaic conceptions of the Sun's position
between Mars and Venus around a stationary Earth.


Argument 10


" The 10th argument,taken from the periodic times, is as follows; the
apparent movement of the Sun has 365 days which is the mean measure
between Venus' period of 225 days and Mars' period of 687
days.Therefore does not the nature of things shout out loud that the
circuits in which those 365 days are taken up has a mean position
between the circuits of Mars and Venus around the Sun and thus this is
not the circuit of the Sun around the Earth -for none of the primary
planets has its orbit arranged around the Earth,as Brahe admits,but
the circuit of the Earth around the resting Sun,just as the other
planets,namely Mars and Venus,complete their own periods by running
around the Sun." Johannes Kepler

If you absorb the representation, known as the Panis
Quadregesimalis,on page 86 you will be repayed a thousand times over
in enjoying how they figured thins out from an orbitally moving
Earth.This is astronomy and it is as satisfying as it is spectacular
when you surmount the obstacles put in place by celestial sphere
observers.





On Jan 28, 10:18 am, "kajlina" <china_...@sina.com> wrote:
Quote:
The period of rotation of Venus is 243 days while its period of
revolution is 225 days.
1.One day on Venus amounts to how many days on Earth?
2. If Venus's direction of rotation was the same as its direction of
revolution, then one day on Venus amounts to how many days on Earth?

I think both answers are 243 days. I suppose whatever the direction of
rotation is, the period of rotation doesn't change. Am I correct?
View user's profile Send private message
oriel36
Posted: Sun Jan 28, 2007 8:19 am
Joined: 31 May 2004 Posts: 942
Would you like to see how the old astronomers figured out how long it
takes the other planets to complete an annual orbit by using the
annual orbital motion of the Earth ?.

http://mitpress.mit.edu/journals/pdf/POSC_13_1_74_0.pdf


If you turn to page 86 you will see how astronomers plotted the motion
of Mars in terms of the stellar background broken into
constellational divisions.


You then compare the orbital cycle of Earth with that of Mars by
taking note of how many times the Earth overtakes Mars,in the words of
Kepler himself -


"Copernicus, by attributing a single annual motion to the earth,
entirely rids the planets of these extremely intricate coils [spiris],
leading the individual planets into their respective orbits
[orbitas],quite bare and very nearly circular. In the period of time
shown in the diagram, Mars traverses one and the same orbit as many
times as the 'garlands' [corollas] you see looped towards the centre,
with one extra, making nine times, while at the same time the repeats
its circle sixteen times "


Using this procedure for Venus,Kepler could then affirm through his
10th argument for heliocentricity why the Earth's motion between Venus
and Mars replaced the Ptolemaic conceptions of the Sun's position and
motion between Mars and Venus around a stationary Earth.


Argument 10


" The 10th argument,taken from the periodic times, is as follows; the
apparent movement of the Sun has 365 days which is the mean measure
between Venus' period of 225 days and Mars' period of 687
days.Therefore does not the nature of things shout out loud that the
circuits in which those 365 days are taken up has a mean position
between the circuits of Mars and Venus around the Sun and thus this is
not the circuit of the Sun around the Earth -for none of the primary
planets has its orbit arranged around the Earth,as Brahe admits,but
the circuit of the Earth around the resting Sun,just as the other
planets,namely Mars and Venus,complete their own periods by running
around the Sun." Johannes Kepler


If you absorb the representation, known as the Panis
Quadregesimalis,on page 86 you will be repayed a thousand times over
in enjoying how they figured things out from an orbitally moving
Earth.It is a shared astronomical heritage so you enjoy it as coming
from brilliant people who knew what they were doing. The astronomical
explanation will look fresh to you insofar as most here are into
celestial sphere 'predictions' and hardly take account of the active
motions of the Earth around the Sun along with the other planets.





On Jan 28, 10:18 am, "kajlina" <china_...@sina.com> wrote:
Quote:
The period of rotation of Venus is 243 days while its period of
revolution is 225 days.
1.One day on Venus amounts to how many days on Earth?
2. If Venus's direction of rotation was the same as its direction of
revolution, then one day on Venus amounts to how many days on Earth?

I think both answers are 243 days. I suppose whatever the direction of
rotation is, the period of rotation doesn't change. Am I correct?
View user's profile Send private message
Greg Neill
Posted: Sun Jan 28, 2007 10:05 am
Guest
"kajlina" <china_108@sina.com> wrote in message
news:1169979502.689368.297130@a34g2000cwb.googlegroups.com...
Quote:
The period of rotation of Venus is 243 days while its period of
revolution is 225 days.
1.One day on Venus amounts to how many days on Earth?
2. If Venus's direction of rotation was the same as its direction of
revolution, then one day on Venus amounts to how many days on Earth?

I think both answers are 243 days. I suppose whatever the direction of
rotation is, the period of rotation doesn't change. Am I correct?


http://cseligman.com/text/sky/rotationvsday.htm
Dave
Posted: Mon Jan 29, 2007 2:13 am
Guest
She wants help to do her homework, Oriel, and you give her this. I guess
you could make the point that she needs to slog through your cueiform
writing to truely understand. But just remember, truely intelligent people
don't have to make themselves difficult to understand. The best way to learn
something is to try and teach it. The best way to teach is to simplify, not
obfuscate. Challenge yourself to make what you feel is complicated, simpler.
It is.

Dave
Paul Schlyter
Posted: Mon Jan 29, 2007 3:42 am
Guest
In article <3ggvh.826370$R63.384598@pd7urf1no>,
Dave <Dave@pleasereplytonewsgroup.ca> wrote:

Quote:
The best way to learn something is to try and teach it.

I wouldn't want to be a pupil of such a teacher. After all, isn't the
teacher supposed to already know what he's teaching?

Or perhaps what you wrote is merely a confirmation of this:

Those who can, do.
Those who can't, teach.
Those who can't teach, teach teachers.

:-)
--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
oriel36
Posted: Mon Jan 29, 2007 6:32 am
Joined: 31 May 2004 Posts: 942
On Jan 29, 6:13 am, "Dave" <D...@pleasereplytonewsgroup.ca> wrote:
Quote:
She wants help to do her homework, Oriel, and you give her this. I guess
you could make the point that she needs to slog through your cueiform
writing to truely understand. But just remember, truely intelligent people
don't have to make themselves difficult to understand. The best way to learn
something is to try and teach it. The best way to teach is to simplify, not
obfuscate. Challenge yourself to make what you feel is complicated, simpler.
It is.

Dave

You lousy freaks teach that the Earth rotates through 360 degrees in
23 hours 56 minutes 04 seconds when nothing supports such a
correlation between clocks and axial rotation.

Truly intelligent people !,where in God's name are they in the once
noble discipline of astronomy ?.What did humnanity do to deserve have
a bunch opf celestial sphere guys vandalise and wreck the richest
heritage of natural phenomena insofar as we live by the astronomical
cycles.

There is another crowd who also have basic problems with the 24 hour
day and natural phenomena and they like to keep things simpleminded
too.the difference is that they are in the moinority while you
celestial sphere creeps dominate.
View user's profile Send private message
AustinMN
Posted: Mon Jan 29, 2007 10:24 am
Guest
On Jan 29, 1:42 am, pau...@saaf.se (Paul Schlyter) wrote:
Quote:
Those who can, do.
Those who can't, teach.
Those who can't teach, teach teachers.

:-)

In that case, Oriel must teach those who teach teachers. ;)

Austin
AustinMN
Posted: Mon Jan 29, 2007 10:29 am
Guest
On Jan 29, 4:32 am, "oriel36" <geraldkelle...@yahoo.com> wrote:
Quote:
DaveYou lousy freaks teach that the Earth rotates through 360 degrees in
23 hours 56 minutes 04 seconds when nothing supports such a
correlation between clocks and axial rotation.

We teach that because it does. The only other possible conclusion
that one can come to is that the entire universe revolves around the
earth (or the solar system) once a year. There is no other possible
conclusion, and only those who are misguided, blind, stuipd, or insane
think otherwise -- Including you.

You need help, oriel. Either you are wrong, or the entire world is
wrong. I'm betting on you, and I am not a gambling man.

Austin
Chris L Peterson
Posted: Mon Jan 29, 2007 11:52 am
Guest
On Mon, 29 Jan 2007 07:42:24 GMT, pausch@saaf.se (Paul Schlyter) wrote:

Quote:
The best way to learn something is to try and teach it.

I wouldn't want to be a pupil of such a teacher. After all, isn't the
teacher supposed to already know what he's teaching?

Teaching something forces you to learn it with a sort of depth you may
never achieve otherwise. It isn't a question of not knowing what you are
going to teach; teaching enhances the teacher's knowledge as well as the
student's.

Put a little differently, teaching a subject forces you to parse it
intellectually in quite a different way than simply using it does.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
oriel36
Posted: Mon Jan 29, 2007 1:26 pm
Joined: 31 May 2004 Posts: 942
On Jan 29, 2:29 pm, "AustinMN" <tacooper...@hotmail.com> wrote:
Quote:
On Jan 29, 4:32 am, "oriel36" <geraldkelle...@yahoo.com> wrote:

DaveYou lousy freaks teach that the Earth rotates through 360 degrees in
23 hours 56 minutes 04 seconds when nothing supports such a
correlation between clocks and axial rotation.We teach that because it does. The only other possible conclusion
that one can come to is that the entire universe revolves around the
earth (or the solar system) once a year. There is no other possible
conclusion, and only those who are misguided, blind, stuipd, or insane
think otherwise -- Including you.

You need help, oriel. Either you are wrong, or the entire world is
wrong. I'm betting on you, and I am not a gambling man.

Austin

Most people on the planet already know that the correlation between
clocks and axial rotation is 24 hours through 360 degrees or 15
degrees per hour,what they do not know is how it came to be this way
and that is fine,a little effort to understand the two step process
with the Equation of Time as the connecting principles makes it a joy
to behold.

Here is what a teacher teaches and no other way regarding the
relationship between clocks and axial rotation.There is plenty of room
for descriptive improvement but the basic tenets are exactly as I
outline.

Our pre-heiocentric astronomical ancestors knew that the Total length
of a day ,do you hear,the Total length of the natural day as gauged
from noon is unequal.They devised a noon correction,now known as the
Equation of Time, to equalise the natural variations to an equable 24
hour day.The correction also keeps one 24 hour day elapsing seamlessly
into the next 24 hour day

That is the first step in a two step process.Now the next step.


Copernicus used the faster orbitral motion of the Earth to explain the
observed behavior of the outer planets as their slower forward motion
appears to make them fall behind temporarily -

http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif

This allowed the heliocentric astronomers to appreciate that the daily
cycle was due to axial rotation.They then adapted the existing
Equation of Time correction which creates the 24 hour day to the idea
that if you correlate geographical longitudes with this 24 hour day in
terms of 4 minutes for each degree of seperation,you can determine
location by working off the principle that axial rotation and clocks
are always in sync.

The Equation of Time correction which keeps one 24 hour day elapsing
into the next 24 hour day also maintains the correlation between
clocks and axial rotation ,it does not need an external reference but
it does need clever people to distinguish between a human devised
principle and how they grafted it on to the insight that axial
rotation is responsible for the daily cycle.

So,who will teach the teachers because if you get the basic
relationship between axial and orbital motion wrong,and I assure you
that you have through the sidereal justification,you can forget about
getting humanity to appreciate astronomy which in turn is needed to
appreciate climatology,geology and basically all phenomena of this
majestic planet.
View user's profile Send private message
oriel36
Posted: Mon Jan 29, 2007 1:39 pm
Joined: 31 May 2004 Posts: 942
On Jan 29, 3:52 pm, Chris L Peterson <c...@alumni.caltech.edu> wrote:
Quote:
On Mon, 29 Jan 2007 07:42:24 GMT, pau...@saaf.se (Paul Schlyter) wrote:
The best way to learn something is to try and teach it.

I wouldn't want to be a pupil of such a teacher. After all, isn't the
teacher supposed to already know what he's teaching?Teaching something forces you to learn it with a sort of depth you may
never achieve otherwise. It isn't a question of not knowing what you are
going to teach; teaching enhances the teacher's knowledge as well as the
student's.

Put a little differently, teaching a subject forces you to parse it
intellectually in quite a different way than simply using it does.

_________________________________________________

Chris L Peterson
Cloudbait Observatoryhttp://www.cloudbait.com

How many parents unwittingly put their kids in the hands of people who
will makes sure they end up with no appreciation of natural phenomena
and especially astronomy,good kids who would thrive on the works of
the great astronomers are forced into accepting that meaningless
equations allied with novelistic concepts.Half these kids are
probably feeling the strain of knowing that they are good at something
but cannot find their way past the experimental cult known as
empiricism.

How many people here could easily grasp how the faster Earth
overtaking the slower forward moving outer planets creates the
illusion of the planets appearing to fall back temporarily -

http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif

When these people see how Copernicus worked out that the Earth has an
orbital motion between Venus and Mars,how could they then go back to
the later Newtonian view which is wrong -

" For to the earth planetary motions appear sometimes direct,
sometimes stationary, nay, and sometimes retrograde. But from the sun
they are always seen direct," Newton

It not only costs nothing to adopt to the correct view based on
seeing orbital motions around the Sun from an orbitally moving
Earth,it is the only way to resolve the observed behavior of the
planets.There are those who simply cannot see where Newton got it
wrong but I am still waiting to see who can actually see the faster
Earth overtaking the slower forward moving outer planets.

Kids,especially teenagers would love the way Copernicus and Kepler
thought and it is all made easy through modern imaging.

So who will teach the teachers what is correct and what is not.
View user's profile Send private message
AustinMN
Posted: Mon Jan 29, 2007 2:43 pm
Guest
oriel36 utterly ignored the truth when he spilled out:
Quote:
On Jan 29, 2:29 pm, "AustinMN" <tacooper...@hotmail.com> wrote:

On Jan 29, 4:32 am, "oriel36" <geraldkelle...@yahoo.com> wrote:

DaveYou lousy freaks teach that the Earth rotates through 360 degrees in
23 hours 56 minutes 04 seconds when nothing supports such a
correlation between clocks and axial rotation.

<attribution repaired>

Quote:
We teach that because it does. The only other possible conclusion
that one can come to is that the entire universe revolves around the
earth (or the solar system) once a year. There is no other possible
conclusion, and only those who are misguided, blind, stuipd, or insane
think otherwise -- Including you.

You need help, oriel. Either you are wrong, or the entire world is
wrong. I'm betting on you, and I am not a gambling man.

Austin

Most people on the planet already know that the correlation between
clocks and axial rotation is 24 hours through 360 degrees or 15
degrees per hour,

Except it isn't. The only way this can be true is if the entire
universe revolves around us once per year.

Quote:
what they do not know is how it came to be this way
and that is fine, a little effort to understand the two step process
with the Equation of Time as the connecting principles makes it a joy
to behold.

Our pre-heiocentric astronomical ancestors knew that the Total length
of a day ,do you hear,the Total length of the natural day as gauged
from noon is unequal. They devised a noon correction,now known as the
Equation of Time, to equalise the natural variations to an equable 24
hour day.The correction also keeps one 24 hour day elapsing seamlessly
into the next 24 hour day

That is the first step in a two step process.Now the next step.

OK so far.

Quote:
Copernicus used the faster orbitral motion of the Earth to explain the
observed behavior of the outer planets as their slower forward motion
appears to make them fall behind temporarily -

http://antwrp.gsfc.nasa.gov/apod/image/0112/JuSa2000_tezel.gif

This allowed the heliocentric astronomers to appreciate that the daily
cycle was due to axial rotation. They then adapted the existing
Equation of Time correction which creates the 24 hour day to the idea
that if you correlate geographical longitudes with this 24 hour day in
terms of 4 minutes for each degree of seperation, you can determine
location by working off the principle that axial rotation and clocks
are always in sync.

Yep. Except it's about 360 degrees of longitude, not 360 degrees of
rotation.

Quote:
The Equation of Time correction which keeps one 24 hour day elapsing
into the next 24 hour day also maintains the correlation between
clocks and axial rotation,

How does it do that? By adding an extra day every four years (except
even that is not correct and requires an adjustment every 100 years
except even that is not correct and requires an additional adjustment
every 400 years except even that is not correct requiring additional
adjustments...)

Quote:
it does not need an external reference

The external reference is THE ONLY REASON IT EXISTS AT ALL; the
external reference is the only reason we are aware that there is a
need to make the correction.

Quote:
So,who will teach the teachers because if you get the basic
relationship between axial and orbital motion wrong,and I assure you
that you have through the sidereal justification,you can forget about
getting humanity to appreciate astronomy which in turn is needed to
appreciate climatology,geology and basically all phenomena of this
majestic planet.

You are seriously deluded. You need professional help.

Austin
 
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