Distance From Earth to Mars

I am looking for a formula or an algorithm that will calculate
the distance from the Earth to Mars at any time. IOW, a formula
that calculates distance as a function of time.

Does anyone know where I can find such a formula???

--
+----------------------------------------------------------------+
| Charles and Francis Richmond richmond at plano dot net |
+----------------------------------------------------------------+

"Charles Richmond" wrote in message
...
I am looking for a formula or an algorithm that will calculate
the distance from the Earth to Mars at any time. IOW, a formula
that calculates distance as a function of time.

Does anyone know where I can find such a formula???


There is no simple "formula"; you have to compute the heliocentric position
of both the Earth and Mars; knowing that, you can then find the distance
between the two.

The "classic" book for astronomical calculations is Jean Meeus'
"Astronomical Algorithms", published by Willman-Bell.

Paul Schlyter's written an excellent web page about low-precision planetary
position calculations which you'll find at
http://home.tiscali.se/pausch/comp/ppcomp.html

If you want high-precision calculations you need some serious computing
effort; you might perhaps use the "ephemeris" feature in the free demo
version of my own humble attempt at astronomy software, "SkyMap Pro", which
you'll find at http://www.skymap.com

Regards,

Chris

"Charles Richmond" wrote in message
...
I am looking for a formula or an algorithm that will calculate
the distance from the Earth to Mars at any time. IOW, a formula
that calculates distance as a function of time.

Does anyone know where I can find such a formula???


There is no simple "formula"; you have to compute the heliocentric position
of both the Earth and Mars; knowing that, you can then find the distance
between the two.

The "classic" book for astronomical calculations is Jean Meeus'
"Astronomical Algorithms", published by Willman-Bell.

Paul Schlyter's written an excellent web page about low-precision planetary
position calculations which you'll find at
http://home.tiscali.se/pausch/comp/ppcomp.html

If you want high-precision calculations you need some serious computing
effort; you might perhaps use the "ephemeris" feature in the free demo
version of my own humble attempt at astronomy software, "SkyMap Pro", which
you'll find at http://www.skymap.com

Regards,

Chris