29:null 2a:["$","title",null,{"children":"Sun Position in 900 Bytes | Michaël Guitton | Observable"}] 2f:T755,(async function* (rate) { const getPhase = (a, h) => { const time = a < 180 ? "morning" : "evening"; return h < -18 ? "night " + (a < 180 ? "(after nadir)" : "(before nadir)") : h < -6 ? time + " blue hour" : h < -0.833 ? time + " twilight" : h < 6 ? time + " golden hour" : "day " + (a < 180 ? "(before noon)" : "(after noon)"); }; const rightAlign = 'style="text-align: right; font-variant-numeric: tabular-nums;"'; const rotate = (deg) => `style="display: inline-block; transform: rotate(${deg}deg)"`; const getColor = (h) => h < -18 ? "#74add1" : h < -6 ? "#abd9e9" : h < -0.833 ? "#e0f3f8" : h < 6 ? "#fee090" : "#ffffaa"; while (true) { yield html`

${cities .map(([name, lng, lat]) => { const { azimuth, altitude } = getSunPosition(Date.now(), lng, lat); const d = 180 / Math.PI; const a = d * azimuth; const h = d * altitude; return ` `; }) .join("")}

City	↓ Long	Lat	Sun Phase	Altitude	Azimuth
${name}	${lng.toFixed(1)}	${lat.toFixed(1)}	${getPhase(a, h)}	${h.toFixed(2)}° →	${a.toFixed(2)}° ↑

`; await Promises.delay(rate); } })(interval)30:T85e,cities = [ ["London", -0.127758, 51.507351], ["Berlin", 13.404954, 52.520008], ["Amsterdam", 4.895168, 52.370216], ["Helsinki", 24.938379, 60.169857], ["Paris", 2.352222, 48.856613], ["Barcelona", 2.173404, 41.385063], ["Lisbon", -9.139337, 38.722252], ["Budapest", 19.040236, 47.497913], ["Prague", 14.437800, 50.075539], ["Madrid", -3.703790, 40.416775], ["Vienna", 16.373819, 48.208176], ["Dublin", -6.260310, 53.349804], ["Reykjavik", -21.942400, 64.147209], ["Copenhagen", 12.568337, 55.676098], ["Stockholm", 18.068581, 59.329323], ["Dakar", -17.467686, 14.716677], ["Kyiv", 30.542721, 50.447731], ["Moscow", 37.617298, 55.755825], ["Minsk", 27.561523, 53.904541], ["Novosibirsk", 82.933952, 55.018803], ["Rome", 12.496365, 41.902782], ["Munich", 11.581981, 48.135124], ["Istanbul", 28.978359, 41.008240], ["Baghdad", 44.361488, 33.312805], ["Tehran", 51.388973, 35.689198], ["Kabul", 69.207489, 34.555347], ["Warsaw", 21.012230, 52.229675], ["Oslo", 10.752245, 59.913868], ["Bangkok", 100.501762, 13.756331], ["Singapore", 103.819839, 1.352083], ["Kuala Lumpur", 101.686852, 3.139003], ["Tokyo", 139.691711, 35.689487], ["Hong Kong", 114.109497, 22.396427], ["Seoul", 126.977966, 37.566536], ["Taipei", 121.565414, 25.032969], ["Shanghai", 121.473701, 31.230391], ["Beijing", 116.407394, 39.904202], ["Bangalore", 77.594566, 12.971599], ["New York City", -74.005974, 40.712776], ["San Francisco", -122.419418, 37.774929], ["Los Angeles", -118.243683, 34.052235], ["Vancouver", -123.120735, 49.282730], ["Seattle", -122.332069, 47.606209], ["Boston", -71.058884, 42.360081], ["Austin", -97.743057, 30.267153], ["Toronto", -79.383186, 43.653225], ["Washington, DC", -77.036873, 38.907192], ["Montreal", -73.567253, 45.501690], ["Mexico City", -99.133209, 19.432608], ["Buenos Aires", -58.381557, -34.603683], ["Sao Paulo", -46.633308, -23.550520], ["Sydney", 151.209900, -33.865143], ["Melbourne", 144.946457, -37.840935], ["Auckland", 174.763336, -36.848461], ["Honolulu", -157.858093, 21.315603] ].sort((a, b) => a[1] - b[1])31:[] 2d:{"id":"084e7812b2149ff4","slug":null,"title":"Sun Position in 900 Bytes","thumbnail":"8ee8afe753d478282196287aee9ea89dc6cd9ef731c84549b57cfecc4212c4af","access_level":"public","create_time":"$D2023-07-17T10:32:46.062Z","update_time":"$D2024-02-08T10:45:35.573Z","view_time":null,"first_public_time":"$D2023-07-17T10:32:46.062Z","fork":{"id":"38a8d14661d2af49","slug":"sun-position-in-900-bytes","title":"Sun Position in 900 Bytes","owner":{"id":"78f29d059906819a","login":"mourner","name":"Volodymyr Agafonkin"}},"stars":0,"starred":false,"owner":{"type":"team","id":"4c1622bb5c37477f","login":"galopin","name":"Michaël Guitton","avatar_url":"https://avatars-next.observableusercontent.com/10e2fe999ac95c8686156fd07e96a686520149a4eef18a95f97795b7a7be1e29","tier":"starter_2024"},"version":376,"publish_version":null,"role":null,"authored":false,"authors":[{"type":"individual","id":"950eb34948878085","login":"galopin","name":"Michaël Guitton","avatar_url":"https://avatars-next.observableusercontent.com/b59822ff41962e9448473fadd4a11819ac725b074ad3868aabf532bade0ac00d","tier":null}],"members":[{"type":"individual","id":"950eb34948878085","login":"galopin","name":"Michaël Guitton","avatar_url":"https://avatars-next.observableusercontent.com/b59822ff41962e9448473fadd4a11819ac725b074ad3868aabf532bade0ac00d","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"subscribed":null,"forks":0,"collection":null,"type":"notebook","body":{"title":"Sun Position in 900 Bytes","cells":[{"id":356,"value":"# Sun Position in 900 Bytes","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":373,"value":"A tiny function to get the position of the Sun in the sky given date/time and location.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":0,"value":"The code is based on the formulas from the 2nd edition of Jean Meeus’s [Astronomical Algorithms](https://www.willbell.com/math/mc1.htm) book.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":371,"value":"This function accepts a Unix timestamp (in milliseconds), longitude and latitude.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":223,"value":"It returns an object with the following properties:\n\n- `azimuth`: `0` to `2π` \n North-based Sun azimuth in radians relative to the observer;\n- `altitude`: `-π/2` to `π/2` \n Sun altitude in radians relative to the observer.","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":4,"value":"getSunPosition = (date, lng, lat) => {\n const {sin, cos, asin, atan2, PI} = Math, \n r = PI / 180, t = date / 315576e7 - 0.3,\n m = r * (357.52911 + t * (35999.05029 - t * 1537e-7)), c = r * (125.04 - 1934.136 * t),\n l = r * (280.46646 + t * (36000.76983 + t * 3032e-7) + (1.914602 - t * (4817e-6 - t * 14e-6)) * sin(m) - \n 569e-5 - 478e-5 * sin(c)) + (0.019993 - 101e-6 * t) * sin(2 * m) + 289e-6 * sin(3 * m),\n e = r * (84381.448 - t * (46.815 - t * (59e-5 + 1813e-6 * t))) / 3600 + r * 256e-5 * cos(c),\n sl = sin(l), cr = cos(r * lat), sr = sin(r * lat), d = asin(sin(e) * sl),\n h = r * (280.46061837 + 13184999.8983375 * t + lng) - atan2(cos(e) * sl, cos(l)),\n sd = sin(d), cd = cos(d), ch = cos(h);\n return {\n azimuth: PI + atan2(sin(h), ch * sr - cr * sd / cd), \n altitude: asin(sr * sd + cr * cd * ch)\n };\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":364,"value":"## Example","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":318,"value":"Let’s use this to continuously calculate the current Sun position for some cities:","pinned":false,"hidden":false,"mode":"md","author":"$undefined","summary":"$undefined","output":"","database":"$undefined"},{"id":40,"value":"$2f","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":101,"value":"$30","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":367,"value":"viewof interval = ((step) =>\n Inputs.range([step, 4 * step], {\n label: \"Refresh rate\",\n step,\n value: step\n }))(15000)","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W31","stdlib":"1","titling":"auto"}} 2e:"$2d:body"