drawJupiterSaturn.frink

View or download drawJupiterSaturn.frink in plain text format


/** 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
*/


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.print[]


View or download drawJupiterSaturn.frink in plain text format


This is a program written in the programming language Frink.
For more information, view the Frink Documentation or see More Sample Frink Programs.

Alan Eliasen was born 18658 days, 12 hours, 35 minutes ago.