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I'm looking for a simple API that will allow me to get positions of planets and the moon for a given date, location and time.
Does anyone know an API like that?
Any suggestions or alternatives would be appreciated.

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  • $\begingroup$ I think it is not really an API, it is more like a database (although it can have an API). Celestia, Google Sky Map, both have this DB. Celestia is opensource, and its database is free. $\endgroup$
    – peterh
    Aug 12, 2019 at 14:04
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    $\begingroup$ JPL HORIZONS will do this and is callable from Python docs. It may not meet the definition of "simple" and it may not integrate with your other code however. $\endgroup$ Aug 12, 2019 at 16:15
  • $\begingroup$ There may be an answer at Where can I find/visualize planets/stars/moons/etc positions? or not, I don't really know what does or doesn't count as an API for you in your case, or if you really need a proper API or something else will do. If you can use Python then Skyfield works quite nicely. If you like compiled code, then Spice... $\endgroup$
    – uhoh
    Aug 13, 2019 at 0:37
  • $\begingroup$ Also see Python API for JPL Horizons? where an answer mentions astroquery (as does astrosnapper's comment above). $\endgroup$
    – uhoh
    Aug 13, 2019 at 0:41
  • $\begingroup$ Thanks guys for your suggestions. I'll definitely check out the python libraries. $\endgroup$ Aug 13, 2019 at 6:05

1 Answer 1

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Astropy is one option:

from astropy.time import Time
from astropy.coordinates import solar_system_ephemeris, EarthLocation
from astropy.coordinates import get_body, get_moon
from astropy.coordinates import SkyCoord, EarthLocation, AltAz
from astropy import units as u
import time;

t = Time("2019-08-11 11:00", scale="utc")
loc = EarthLocation(lat=38.2464000*u.deg, lon=274.236400*u.deg, height=0*u.m)

with solar_system_ephemeris.set('jpl'):
  moon = get_body('moon', t, loc)

altazframe = AltAz(obstime=t, location=loc, pressure=0)
moonaz=moon.transform_to(altazframe)

print(moonaz.alt.degree,moonaz.az.degree)

If you want a library you can ship with a product, you'll want something much smaller. I am actually working on a library converted to many different languages to do just that. Only the JavaScript version has a working Alt Az example, but it should be easy to convert to other languages (and will be eventually).

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