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Show Seth/Gregorian astronomy columns and dual-date lunar event list

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Seth
2026-03-09 02:36:56 +00:00
parent 9bd245d870
commit 196cf7557f
2 changed files with 109 additions and 21 deletions
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astro.js
+71 -8
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@@ -143,6 +143,54 @@ function dayLengthStr(riseJD, setJD) {
return `${h}h ${String(m).padStart(2,"0")}m`;
}
function jdToDecimalTime(jd) {
const frac = ((jd + 0.5) % 1 + 1) % 1;
const dec = frac * 10;
const h = Math.floor(dec);
const m = Math.floor((dec - h) * 100);
return `${h}:${String(m).padStart(2, "0")}`;
}
function dayLengthDecimalStr(riseJD, setJD) {
const decHours = (setJD - riseJD) * 10;
const h = Math.floor(decHours);
const m = Math.floor((decHours - h) * 100);
return `${h}:${String(m).padStart(2, "0")}`;
}
// ── Seth date helpers ───────────────────────────────────────────────────────
function isLeapYear(year) {
return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
}
function getDayOfYearUTC(date) {
const y = date.getUTCFullYear();
const m = date.getUTCMonth() + 1;
const d = date.getUTCDate();
const cum = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
let doy = cum[m - 1] + d;
if (isLeapYear(y) && m > 2) doy++;
return { year: y, doy };
}
function toSethDate(year, dayOfYear) {
const leap = isLeapYear(year);
if (leap && dayOfYear === 60) return { type: "leapday", year };
const idx = (leap && dayOfYear > 60 ? dayOfYear - 1 : dayOfYear) - 1;
if (idx < 360) {
const month = Math.floor(idx / 36);
const dayInM = idx % 36;
return { type: "month", year, month, day: dayInM };
}
return { type: "holiday", year, holiday: idx - 360 };
}
function sethLog(sd) {
if (sd.type === "leapday") return `Leap Day ${sd.year}`;
if (sd.type === "holiday") return `H${sd.holiday}.${sd.year}`;
return `${String(sd.day).padStart(2, "0")}.${sd.month}.${sd.year}`;
}
// ── Solstice / Equinox (Meeus Table 27.a + correction) ───────────────────────
// Returns approximate JD for each event in a given year
// season: 0=March equinox, 1=June solstice, 2=September equinox, 3=December solstice
@@ -246,15 +294,27 @@ function render() {
const jd = jdFromDate(date);
const nextNewJD = nextMoonPhaseJD(jd, 0);
const nextFullJD = nextMoonPhaseJD(jd, 2);
document.getElementById("nextNew").textContent = dateFromJD(nextNewJD).toLocaleDateString("en-US", { month: "short", day: "numeric", timeZone: "UTC" });
document.getElementById("nextFull").textContent = dateFromJD(nextFullJD).toLocaleDateString("en-US", { month: "short", day: "numeric", timeZone: "UTC" });
const nextNewDate = dateFromJD(nextNewJD);
const nextFullDate = dateFromJD(nextFullJD);
const nextNewSeth = toSethDate(getDayOfYearUTC(nextNewDate).year, getDayOfYearUTC(nextNewDate).doy);
const nextFullSeth = toSethDate(getDayOfYearUTC(nextFullDate).year, getDayOfYearUTC(nextFullDate).doy);
document.getElementById("nextNewSeth").textContent = sethLog(nextNewSeth);
document.getElementById("nextNewGreg").textContent = nextNewDate.toLocaleDateString("en-US", { month: "short", day: "numeric", year: "numeric", timeZone: "UTC" });
document.getElementById("nextFullSeth").textContent = sethLog(nextFullSeth);
document.getElementById("nextFullGreg").textContent = nextFullDate.toLocaleDateString("en-US", { month: "short", day: "numeric", year: "numeric", timeZone: "UTC" });
// Sun
const sun = sunriseSunset(date, LAT, LON);
document.getElementById("sunrise").textContent = sun.rise || (sun.alwaysUp ? "Midnight sun" : "Below horizon");
document.getElementById("sunset").textContent = sun.set || (sun.alwaysUp ? "Midnight sun" : "Below horizon");
document.getElementById("solarNoon").textContent = sun.noon;
document.getElementById("dayLen").textContent = sun.rise && sun.set ? dayLengthStr(sun.riseJD, sun.setJD) : "—";
document.getElementById("sunriseSeth").textContent = sun.riseJD ? jdToDecimalTime(sun.riseJD) : "—";
document.getElementById("sunriseGreg").textContent = sun.rise || (sun.alwaysUp ? "Midnight sun" : "Below horizon");
document.getElementById("sunsetSeth").textContent = sun.setJD ? jdToDecimalTime(sun.setJD) : "—";
document.getElementById("sunsetGreg").textContent = sun.set || (sun.alwaysUp ? "Midnight sun" : "Below horizon");
document.getElementById("solarNoonSeth").textContent = sun.noonJD ? jdToDecimalTime(sun.noonJD) : "—";
document.getElementById("solarNoonGreg").textContent = sun.noon;
document.getElementById("dayLenSeth").textContent = sun.rise && sun.set ? dayLengthDecimalStr(sun.riseJD, sun.setJD) : "—";
document.getElementById("dayLenGreg").textContent = sun.rise && sun.set ? dayLengthStr(sun.riseJD, sun.setJD) : "—";
document.getElementById("moonAgeSeth").textContent = `${(age * (10 / 29.53058867)).toFixed(2)} days`;
document.getElementById("moonAgeGreg").textContent = `${age.toFixed(1)} days`;
@@ -290,9 +350,12 @@ function render() {
ul.innerHTML = "";
allEvents.forEach(ev => {
const li = document.createElement("li");
const ds = ev.date.toLocaleDateString("en-US", { month: "short", day: "numeric", timeZone: "UTC" });
const ds = ev.date.toLocaleDateString("en-US", { month: "short", day: "numeric", year: "numeric", timeZone: "UTC" });
const sy = getDayOfYearUTC(ev.date);
const sseth = toSethDate(sy.year, sy.doy);
const sds = sethLog(sseth);
const isToday = dateToParam(ev.date) === dateToParam(date);
li.innerHTML = `<span class="event-name"${isToday ? ' style="color:var(--accent)"' : ""}>${ev.name}</span><span>${ds}</span>`;
li.innerHTML = `<span class="event-name"${isToday ? ' style="color:var(--accent)"' : ""}>${ev.name}</span><span class="event-dual"><span>${sds}</span><span>${ds}</span></span>`;
ul.appendChild(li);
});
}