Andy Ross wrote:
Erik Hofman wrote:
Since you are already familiar with this stuff, I need the function to
calculate the sun position (in degrees or radians) above the horizon
at a certain time/lat/lon. What is this normally called:
RightAscension, Declination, Magnitude or something else?
None of the above. :)
Not even "something else"?
:-)
> Right ascention and declination are the
longitude and latitude of the celestial coordinate system. They
specify directions to things that are outside our solar system.
Things inside it will appear to move depending on their relative
position with the earth. Magnitude refers to the brightness of
a star.
The sun position can be computed if you know the orbital parameters
for the earth, but the details are tricky. The way it would work is
to define some "sol-centric" coordinate system in which the earth
moves, compute a line from the earthbound eyepoint to the sun, figure
out what orientation the earth will be in at that moment, and then do
an euler angle decomposition relative to the WGS-84 "up" vector and
the earth's axis.
Basically, it's not easy, which is why it's probably quickest to ask
the author to change the license. :)
Well, I got the feeling everything needed is already present without
those four files, it's just a matter of tying everything together in the
right way. Someone with more knowledge about this stuff might do it in a
relatively short time. It would also clean up the code a bit.
Erik
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