A south polar azimuthal equidistant projection, oriented so that noon is as 12 o'clock, as in xkcd:1335. The map updates continuously.
-
-
Save ryaninvents/4c6b70f9ed689917fa0b165ae2c151e9 to your computer and use it in GitHub Desktop.
Now
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
license: gpl-3.0 |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
<!DOCTYPE html> | |
<meta charset="utf-8" /> | |
<style> | |
body { | |
background: #fcfcfa; | |
} | |
.stroke { | |
fill: none; | |
stroke: #000; | |
stroke-width: 3px; | |
} | |
.fill { | |
fill: #fff; | |
} | |
.graticule { | |
fill: none; | |
stroke: #777; | |
stroke-width: 0.5px; | |
stroke-opacity: 0.5; | |
} | |
.land { | |
fill: #222; | |
} | |
.boundary { | |
fill: none; | |
stroke: #fff; | |
stroke-width: 0.5px; | |
} | |
.night { | |
stroke: steelblue; | |
fill: steelblue; | |
fill-opacity: 0.4; | |
} | |
</style> | |
<body> | |
<script src="//d3js.org/d3.v3.min.js"></script> | |
<script src="//d3js.org/topojson.v1.min.js"></script> | |
<script> | |
var width = 960, | |
height = 960; | |
var π = Math.PI, | |
radians = π / 180, | |
degrees = 180 / π; | |
var circle = d3.geo.circle().angle(90); | |
var projection = d3.geo | |
.azimuthalEqualArea() | |
.scale(150) | |
.translate([width / 2, height / 2]) | |
.clipAngle(180 - 1e-3) | |
.rotate([0, -90]) | |
.precision(0.1); | |
var path = d3.geo.path().projection(projection); | |
var graticule = d3.geo.graticule(); | |
var svg = d3 | |
.select('body') | |
.append('svg') | |
.attr('width', width) | |
.attr('height', height); | |
svg | |
.append('defs') | |
.append('path') | |
.datum({ type: 'Sphere' }) | |
.attr('id', 'sphere') | |
.attr('d', path); | |
svg | |
.append('use') | |
.attr('class', 'stroke') | |
.attr('xlink:href', '#sphere'); | |
svg | |
.append('use') | |
.attr('class', 'fill') | |
.attr('xlink:href', '#sphere'); | |
var g = svg.append('g'); | |
g.append('path') | |
.datum(graticule) | |
.attr('class', 'graticule') | |
.attr('d', path); | |
d3.json('/mbostock/raw/4090846/world-50m.json', function(error, world) { | |
if (error) throw error; | |
g.insert('path', '.graticule') | |
.datum(topojson.feature(world, world.objects.land)) | |
.attr('class', 'land') | |
.attr('d', path); | |
g.insert('path', '.graticule') | |
.datum( | |
topojson.mesh(world, world.objects.countries, function(a, b) { | |
return a !== b; | |
}), | |
) | |
.attr('class', 'boundary') | |
.attr('d', path); | |
var night = svg.append('path').attr('class', 'night'); | |
function updatePosition() { | |
var sun = solarPosition(new Date()), | |
angle = 180 - sun[0]; | |
projection.rotate([angle, -90]); | |
night.datum(circle.origin(sun)).attr('d', path); | |
g.attr( | |
'transform', | |
'translate(' + | |
width / 2 + | |
',' + | |
height / 2 + | |
')' + | |
'rotate(' + | |
angle + | |
')' + | |
'translate(' + | |
-width / 2 + | |
',' + | |
-height / 2 + | |
')', | |
); | |
} | |
d3.timer(updatePosition, 15e3); | |
updatePosition(); | |
}); | |
d3.select(self.frameElement).style('height', height + 'px'); | |
function antipode(position) { | |
return [position[0] + 180, -position[1]]; | |
} | |
function solarPosition(time) { | |
var centuries = (time - Date.UTC(2000, 0, 1, 12)) / 864e5 / 36525, // since J2000 | |
longitude = ((d3.time.day.utc.floor(time) - time) / 864e5) * 360 - 180; | |
return [ | |
longitude - equationOfTime(centuries) * degrees, | |
solarDeclination(centuries) * degrees, | |
]; | |
} | |
// Equations based on NOAA’s Solar Calculator; all angles in radians. | |
// http://www.esrl.noaa.gov/gmd/grad/solcalc/ | |
function equationOfTime(centuries) { | |
var e = eccentricityEarthOrbit(centuries), | |
m = solarGeometricMeanAnomaly(centuries), | |
l = solarGeometricMeanLongitude(centuries), | |
y = Math.tan(obliquityCorrection(centuries) / 2); | |
y *= y; | |
return ( | |
y * Math.sin(2 * l) - | |
2 * e * Math.sin(m) + | |
4 * e * y * Math.sin(m) * Math.cos(2 * l) - | |
0.5 * y * y * Math.sin(4 * l) - | |
1.25 * e * e * Math.sin(2 * m) | |
); | |
} | |
function solarDeclination(centuries) { | |
return Math.asin( | |
Math.sin(obliquityCorrection(centuries)) * | |
Math.sin(solarApparentLongitude(centuries)), | |
); | |
} | |
function solarApparentLongitude(centuries) { | |
return ( | |
solarTrueLongitude(centuries) - | |
(0.00569 + | |
0.00478 * Math.sin((125.04 - 1934.136 * centuries) * radians)) * | |
radians | |
); | |
} | |
function solarTrueLongitude(centuries) { | |
return ( | |
solarGeometricMeanLongitude(centuries) + | |
solarEquationOfCenter(centuries) | |
); | |
} | |
function solarGeometricMeanAnomaly(centuries) { | |
return ( | |
(357.52911 + centuries * (35999.05029 - 0.0001537 * centuries)) * | |
radians | |
); | |
} | |
function solarGeometricMeanLongitude(centuries) { | |
var l = | |
(280.46646 + centuries * (36000.76983 + centuries * 0.0003032)) % 360; | |
return ((l < 0 ? l + 360 : l) / 180) * π; | |
} | |
function solarEquationOfCenter(centuries) { | |
var m = solarGeometricMeanAnomaly(centuries); | |
return ( | |
(Math.sin(m) * | |
(1.914602 - centuries * (0.004817 + 0.000014 * centuries)) + | |
Math.sin(m + m) * (0.019993 - 0.000101 * centuries) + | |
Math.sin(m + m + m) * 0.000289) * | |
radians | |
); | |
} | |
function obliquityCorrection(centuries) { | |
return ( | |
meanObliquityOfEcliptic(centuries) + | |
0.00256 * Math.cos((125.04 - 1934.136 * centuries) * radians) * radians | |
); | |
} | |
function meanObliquityOfEcliptic(centuries) { | |
return ( | |
(23 + | |
(26 + | |
(21.448 - | |
centuries * | |
(46.815 + centuries * (0.00059 - centuries * 0.001813))) / | |
60) / | |
60) * | |
radians | |
); | |
} | |
function eccentricityEarthOrbit(centuries) { | |
return 0.016708634 - centuries * (0.000042037 + 0.0000001267 * centuries); | |
} | |
</script> | |
</body> |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment