/** This draws the great 2020 conjunction of Jupiter and Saturn for any given date. Try: frink drawJupiterSaturn.frink "2020-12-21 06:00 PM" for what is probably the closest visible nighttime approach for Denver, Colorado, USA You will need the 2020-08-09 release of planets.frink for this to work correctly. */ use planets.frink lat = 40 deg North long = 105 deg West if length[ARGS] > 0 d = parseDate[ARGS@0] else d = now[] [jaz, jalt] = Planet.Jupiter.refractedAzimuthAltitude[d, lat, long] [saz, salt] = Planet.Saturn.refractedAzimuthAltitude[d, lat, long] jrad = Planet.Jupiter.radiusAngle[d] srad = Planet.Saturn.radiusAngle[d] // Center on Saturn (because it moves the slowest in the sky) g1 = Planet.drawSaturnRelativeToZenith[d, lat, long, (saz-saz) cos[-salt], -(salt-salt), srad, true, true] g2 = Planet.drawJupiterMoonsRelativeToZenith[d, lat, long, (jaz-saz) cos[-salt], -(jalt-salt), jrad, true, true] g = new graphics g.add[g1] g.add[g2] g.invertGrays[].show[] g.invertGrays[].write["drawJupiterSaturn.png", 1024, undef] g.print[]