/** This draws the 2024 conjunction of Mars and Jupiter and Saturn for any given
    date.  Try:

    frink drawMarsJupiter.frink "2024-08-14 09:00"

    for what is probably the closest approach for
    Denver, Colorado, USA.  Try a few hours early for nighttime.
*/

use planets.frink
lat =   40 deg North
long = 105 deg West

if length[ARGS] > 0
   d = parseDate[ARGS@0]
else
   d = now[]

[maz, malt] = Planet.Mars.refractedAzimuthAltitude[d, lat, long]
[jaz, jalt] = Planet.Jupiter.refractedAzimuthAltitude[d, lat, long]

jrad = Planet.Jupiter.radiusAngle[d]
mrad = Planet.Mars.radiusAngle[d]

// Center on Jupiter (because it moves the slowest in the sky)
g1 = Planet.drawJupiterMoonsRelativeToZenith[d, lat, long, (jaz-jaz) cos[-jalt],
 -(jalt-jalt), jrad, true, true]
g2 = Planet.Mars.drawPolygonRelativeToZenith[d, lat, long, (maz-jaz) cos[-jalt], -(malt-jalt), mrad, true]

g = new graphics
g.add[g1]
g.add[g2]
g.invertGrays[].show[]

g.invertGrays[].write["drawMarsJupiter.png", 2048, undef]
g.invertGrays[].write["drawMarsJupiter.svg", 2048, undef]
g.print[]