Calculating the exact distance between planets

Hello ALL

Where do I find information (data and formulae) to calculate the exact
distance between planets, and to answer questions like "what the max
distance between planet A and planet B, and when it happens"? I'm new
to this, but I thing it will be necessary to know the date of the
aphelion/perihelion of the planets, the angular position of the major
axis, the excentricity of the ellipsis, the tilt of the orbit, and what
more? Epicicles?

TIA
--
Cesar A. K. Grossmann

"Cesar" wrote in message
oups.com...
Hello ALL

Where do I find information (data and formulae) to calculate the exact
distance between planets, and to answer questions like "what the max
distance between planet A and planet B, and when it happens"? I'm new
to this, but I thing it will be necessary to know the date of the
aphelion/perihelion of the planets, the angular position of the major
axis, the excentricity of the ellipsis, the tilt of the orbit, and what
more? Epicicles?

You might want to get hold of a copy of Jean Meus' book,
"Astronomical Algorithms". It contains everything you'll
need to program your own solutions.

Another approach (although it might involve a fair amount
of trial and error to locate closest approaches and
greatest separations) would be to employ the JPL
Horizons on-line ephemeris to generate tables of positions
over time and calculate the desired results from them.
The tabular information might, for example, be imported
into Excel spreadsheets to do so.

JP Horizons can be found at:

http://ssd.jpl.nasa.gov/?horizons

Cesar wrote:
Hello ALL

Where do I find information (data and formulae) to calculate the exact
distance between planets, and to answer questions like "what the max
distance between planet A and planet B, and when it happens"? I'm new
to this, but I thing it will be necessary to know the date of the
aphelion/perihelion of the planets, the angular position of the major
axis, the excentricity of the ellipsis, the tilt of the orbit, and what
more? Epicicles?

TIA


Try this site for info:
http://www.frostydrew.org/observator...ts/booklet.htm

It starts out with a calculation of what it would take to orbit an
object near the earth's surface, but it goes into planetary orbits just
below that. I don't think it has all of the info you're looking for,
but its a start. You can probably get the remainder of the data you are
looking for from a good orrery program. There are several free ones
listed at http://freeware.intrastar.net/planetarium.htm

BTW, 'epicycles' aren't part of the Copernican system, that was the
geocentric Ptolmeic system. In the Ptolemaic system, the planets are
assumed to move in a small circle, called an epicycle, which in turn
moves along a larger circle called a deferent. See
http://en.wikipedia.org/wiki/Epicycle
http://en.wikipedia.org/wiki/Ptolemaic_system
http://en.wikipedia.org/wiki/Coperni...ocentric_model


--
Bill Hudson

Cesar wrote:
Hello ALL

Where do I find information (data and formulae) to calculate the exact
distance between planets, and to answer questions like "what the max
distance between planet A and planet B, and when it happens"? I'm new
to this, but I thing it will be necessary to know the date of the
aphelion/perihelion of the planets, the angular position of the major
axis, the excentricity of the ellipsis, the tilt of the orbit, and what
more? Epicicles?

TIA
--
Cesar A. K. Grossmann


You can find a lot of information he

http://nssdc.gsfc.nasa.gov/planetary/planetfact.html

And he

http://www.solarviews.com/eng/data.htm

Double-A

Bill Hudson wrote:

BTW, 'epicycles' aren't part of the Copernican system, that was the
geocentric Ptolmeic system.

Hey Bill

I know what you're saying here but ... strictly speaking this isn't
exactly so.

"Copernicus and the Need for Epicycles
There is a common misconception that the Copernican model did away with
the need for epicycles. This is not true, because Copernicus was able
to rid himself of the long-held notion that the Earth was the center of
the Solar system, but he did not question the assumption of uniform
circular motion. Thus, in the Copernican model the Sun was at the
center, but the planets still executed uniform circular motion about
it. As we shall see later, the orbits of the planets are not circles,
they are actually ellipses. As a consequence, the Copernican model,
with it assumption of uniform circular motion, still could not explain
all the details of planetary motion on the celestial sphere without
epicycles. The difference was that the Copernican system required many
fewer epicycles than the Ptolemaic system because it moved the Sun to
the center."
http://csep10.phys.utk.edu/astr161/l...opernican.html

"THE COPERNICAN MODEL
Epicycles:
- To achieve accurate predictions of planetary positions, Copernicus
adds epicycles to planetary orbits around Sun.
- Unlike Ptolemy, he does not use epicycles to explain retrograde
motions of planets.
- Epicycles are less fundamental to the Copernican model, but still
necessary.
- They will eventually be eliminated by Kepler (a century later), who
shows that planetary orbits are ellipses, not circles."
http://www.astronomy.ohio-state.edu/.../lecture5.html

"Since the time of Aristarchus, Copernicus was the first to propose
that the Earth was not the center of the solar system but in fact that
the sun was the center of the solar system. This new system is referred
to as the heliocentric system. (Helios was the Greek god of the sun.)
Copernicus however, did not eliminate the need for perfect circles in
astronomical movements. Therefore, he retained the ideas of epicycles
established by Ptolemy. Holding on to epicycles would make the
Copernican system not much more accurate than the Ptolemaic system in
predicting planetary positions."
http://wind.cc.whecn.edu/~marquard/a...my/europe1.htm

etc.

John Zinni wrote:
Bill Hudson wrote:
BTW, 'epicycles' aren't part of the Copernican system, that was the
geocentric Ptolmeic system.

Hey Bill

I know what you're saying here but ... strictly speaking this isn't
exactly so.

[snip]

Thanks for the info!

--
Bill Hudson