Like my other recreation of the xkcd:1335 map projection, but rotated to solar noon at 12 o’clock and with the solar terminator overlaid. The blue region is night. The map updates continuously.
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Now + Solar Terminator
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license: gpl-3.0 |
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<!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: .5px; | |
stroke-opacity: .5; | |
} | |
.land { | |
fill: #222; | |
} | |
.boundary { | |
fill: none; | |
stroke: #fff; | |
stroke-width: .5px; | |
} | |
.night { | |
stroke: steelblue; | |
fill: steelblue; | |
fill-opacity: .3; | |
} | |
</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.azimuthalEquidistant() | |
.scale(150) | |
.translate([width / 2, height / 2]) | |
.clipAngle(180 - 1e-3) | |
.rotate([0, 90]) | |
.precision(.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"); | |
d3.timer(function() { | |
var sun = antipode(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.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 * (46.8150 + centuries * (0.00059 - centuries * 0.001813))) / 60) / 60) * radians; | |
} | |
function eccentricityEarthOrbit(centuries) { | |
return 0.016708634 - centuries * (0.000042037 + 0.0000001267 * centuries); | |
} | |
</script> |
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