Download or view transit3.frink in plain text format
// This program draws the transit of Venus (easily adapted for Mercury)
// across the sun, taking into account a lot of effects.
use planets.frink
use sun.frink
timezone = "Mountain"
lat = 39.58560 degrees North
long = 104.89598 degrees West
/*lat = DMS[40, 33, 35.84] North
long = DMS[105,04,57.64] West*/
df = ### yyyy-MM-dd-HH:mm ###
g = new graphics
//for planet = [Planet.Mercury, Planet.Venus]
planet = Planet.Venus
startdate = #2012-06-05 04:04 PM#
enddate = sunset[startdate, lat, long]
println["Sunset is $enddate"]
g = new graphics
g.backgroundColor[.8, .8, 1]
// Draw the sun
g.color[1,1,0] // Yellow
azsun = 40 deg
altsun = 10 deg
[azsun, altsun] = refractedSunAzimuthAltitude[startdate, lat, long]
sunRadius = sunRadiusAngle[startdate]
g.fillEllipseCenter[(azsun-azsun) cos[-altsun], -(altsun-altsun), 2 sunRadius, 2 sunRadius]
g.color[0,0,0]
win = g.show[]
g.font["SansSerif", 0.01 degree]
dateformat = ###h:mm a###
for d = startdate to enddate step 20 min
{
[azsun, altsun] = refractedSunAzimuthAltitude[d, lat, long]
[azp, altp] = planet.refractedAzimuthAltitude[d, lat, long]
separation = angularSeparation[azsun, altsun, azp, altp]
sunRadius = sunRadiusAngle[d]
venusRadius = planet.radiusAngle[d]
//println[venusRadius -> [0, "deg", "arcmin", "arcsec"]]
flag =""
if separation < sunRadius + venusRadius
{
flag = "*"
if separation < sunRadius - venusRadius
flag = "**"
}
azp = (azp + 180 degrees) mod circle
azsun = (azsun + 180 degrees) mod circle
azsep = (azp-azsun) mod (360 degrees)
if azsep > 180 degrees
azsep = azsep - circle
// Draw Venus
// How much more black could it be? The answer is none. None more black.
x = azsep cos[-altp]
y = -(altp-altsun)
g.fillEllipseCenter[x, y, 2 venusRadius, 2 venusRadius]
g.text[d -> [dateformat, timezone], x - venusRadius, y + venusRadius, "right", "center", 45 deg]
// g.add[planet.drawPolygonRelativeToZenith[d, lat, long, azp, -altp, venusRadius, true]]
win.repaint[]
println[(d->timezone) + "\t" + format[separation,"deg", 5] + "\t" + format[azsep,"deg",2] + "\t$flag" ]
}
g.write["venusChart.svg", 1024, 768]
g.write["venusChart.png", 1024, 768]
g.write["venusChart.html", 1024, 768]
Download or view transit3.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 20217 days, 23 hours, 47 minutes ago.