Help on Astrolgical Calculation

[mail.cordon]

Hi everyone,

I need an algorithm/program that can computer planetory position data
for a given date/time/place. Can anyone please help me to find the same
(source code/algorithm) or explain me how to find/calculate it.

Thanks in advanced,
K Amit

 

[Richard Heathfield]

(e-mail address removed) said:

Hi everyone,

I need an algorithm/program that can computer planetory position data
for a given date/time/place. Can anyone please help me to find the same
(source code/algorithm) or explain me how to find/calculate it.

Here's the obvious method: start with known positions and velocities at
known times of all the masses about whose gravitational influence you care.
Then apply Newton's laws of motion, iteratively. To find the position of a
planet in the night sky at a given point on earth at a given time, you then
only need apply a little elementary trigonometry to the situation.

Here's a less obvious but much easier method: wait until Aries is rising
into Leo and Mars is dominant, and a tall dark stranger will bring you a
surprise package that could save you a lot of trouble! But be wary in your
financial dealings with him.

 

[Walter Roberson]

:I need an algorithm/program that can computer planetory position data
:for a given date/time/place. Can anyone please help me to find the same
source code/algorithm) or explain me how to find/calculate it.

There is no known accurate way to calculate this. This is the "N-Body
Problem", the mathematics of which is chaotic. The positions of the
planets is affected by the position of all the other planets, and
by the position of Sol, and by the composition of the planets, and
by the stellar dynamics of Sol (which determine the mass distribution) --
and all of these are also affected by the positions and mass of the
thousands of minor planets and the positions and mass of all of the
billions of smaller objects.

For example, the position of some of the "shepard moons" in Saturn's
rings depend upon the mass distribution of the ring particles, which in
turn depends upon the planetary electrical field and the details of how
Io ejects mass into orbit... But then the position of Saturn depends
upon the position of the shepard moons, and that affects everything
else.

If you don't mind approximations, you can model the positions
independantly using simple elipses whose foci are determined by the
relative masses of Sol and the planet in question. That is, however,
really only usable for the high-mass planets; the low- mass planets are
much more affected by the influence of the other objects. Keep in mind,
though, that the existance of Neptune and Pluto were deduced based upon
the wobbles in the orbits of the other planets... Mercury in particular
has really noticable orbital deviations from the simple elipse model,
due to relativistic effects (scientists spend years searching for a
planet hidden within Mercury's orbit, until relativity was successfully
applied.)


Beyond that... search for emphemeris programs, such as
http://www.astro.com/swisseph/?lang=e

 

[Barry Schwarz]

Hi everyone,

I need an algorithm/program that can computer planetory position data
for a given date/time/place. Can anyone please help me to find the same
(source code/algorithm) or explain me how to find/calculate it.

Not a C question. You might have better luck in an algorithms group
or one devoted to astronomy.


<<Remove the del for email>>

 

[Randy Howard]

(e-mail address removed) wrote
(in article

Hi everyone,

I need an algorithm/program that can computer planetory position data
for a given date/time/place. Can anyone please help me to find the same
(source code/algorithm) or explain me how to find/calculate it.

Xephem does an excellent job at this sort of thing, and is open
source.

 

[ajm]

Hi,

Here's the obvious method: start with known positions and velocities at
known times of all the masses about whose gravitational influence you care.
Then apply Newton's laws of motion, iteratively. To find the position of a
planet in the night sky at a given point on earth at a given time, you then
only need apply a little elementary trigonometry to the situation.

Might be better computing the N-body Lagrangian and approximating to
the desired degree of accuracy.

Here's a less obvious but much easier method: wait until Aries is rising
into Leo and Mars is dominant, and a tall dark stranger will bring you a
surprise package that could save you a lot of trouble! But be wary in your
financial dealings with him.

I agree with Richard if the stranger offers money take it, otherwise
run...

ajm.

 

[SM Ryan]

(e-mail address removed) wrote:
# Hi everyone,
#
# I need an algorithm/program that can computer planetory position data
# for a given date/time/place. Can anyone please help me to find the same
# (source code/algorithm) or explain me how to find/calculate it.

US Navy Observatory, Ministry of Defence, Greenwich
Observatory, etc. Google should find lots of places.

The simple algorithm is to observe the Kepler ellipse
for each planet, the orbital period, and where on the
ellipse the body throughout its period. The observations
are then updated every half century. (Kepler doesn't include
effects of one planet on another; Newton doesn't include
the curvature of space. Over time the predictions drift
from reality.) That should get you close enough to fine
adjust manually.