ok,
not sure where to ask this but I'm a teacher who dabbles in programming and I'm writing a program to illustrate transfer orbits etc and needed the orbital elelments of the planets and found them here. I just need clarification if the "L mean longitude" tells me where the planet was on the date specified. ie earth's mean logitude is 100.5. Does that mean that earth is 100.5 degrees from the perihelion? Please say yes so I'm on the right track or how far am I off? Any direction is appreciated
cheers
jb

Planetary Mean Orbits (J2000)
(epoch = J2000 = 2000 January 1.5)

Planet
(mean) a e i Omega ~omega L
AU deg deg deg deg
Mercury 0.38709893 0.20563069 7.00487 48.33167 77.45645 252.25084
Venus 0.72333199 0.00677323 3.39471 76.68069 131.53298 181.97973
Earth 1.00000011 0.01671022 0.00005 -11.26064 102.94719 100.46435

I think that L deg of Earth (100.46435) means that at the January 1, 2000, the Earth was at 100.46... degree of longitudel position around the sun. Not sure and hope someone will jump to correct this.

A good source to clarify your doubts is by consult the encyclopedia:

http://en.wikipedia.org/wiki/Planet

Rodolfo

Som links:
NREL Solarpos documentation and source Source code and pretty good documentation for a solar position\intensity calculator.

This is a compact step by step tutorial on calculating basic keplerian orbits for the planets by Paul Schlyter

now it makes more sense.. angle is celestial sphere angle..not sure why my brain got mixed up.. my positions don't look right with the change but it at least is a start...
need to get a overhead map of jan '00 and compare.
thanks guys...

SUCCESS..thanks guys..turns out my rotation matrix had the -ve signs backwards.. which is why the new changes were messed up... and to think I always tell my physics students that that is the biggest error
I'm amazed how accurate it is... or appears to be lol
cheers
jb

Waaaw!