Commit `5395f2f431`

5395f2f431ac9e4015d60992a9990160b8bd56bc

parent: 03334ac382

Verified · cmc

cmc <hello@cleberg.net> · 2026-10-18 21:34 UTC

Add eclipse path maps and local eclipse timings

Layout: unified · split

App/Sources/EclipseScreen.swift added +164

		@@ -0,0 +1,164 @@
	1	import SkyEngine
	2	import SkyRenderer
	3	import SwiftUI
	4
	5	/// Map of a total or annular eclipse's path, with timings at greatest eclipse and for the observer.
	6	struct EclipseScreen: View {
	7	var date: Date
	8	var observer: Observer
	9	var placeName: String
	10	@State private var path: EclipsePath?
	11	@State private var local: LocalEclipse?
	12	@State private var loaded = false
	13	@Environment(\.dismiss) private var dismiss
	14
	15	private let ink = Color(red: 0.95, green: 0.95, blue: 0.93)
	16	private let accent = Color(red: 0.88, green: 0.24, blue: 0.19)
	17
	18	var body: some View {
	19	NavigationStack {
	20	ScrollView {
	21	VStack(alignment: .leading, spacing: 16) {
	22	if let path {
	23	EclipseMap(path: path, observer: observer, ink: ink, accent: accent)
	24	.aspectRatio(1.6, contentMode: .fit)
	25	.accessibilityLabel("Map of the path of the eclipse")
	26	facts(path)
	27	} else if loaded {
	28	Text("This eclipse is partial everywhere, so there is no path to map.").font(.footnote).dimmed(0.7)
	29	} else {
	30	ProgressView().tint(ink).frame(maxWidth: .infinity, minHeight: 200)
	31	}
	32	if loaded { here }
	33	}
	34	.padding(20)
	35	.readableWidth()
	36	}
	37	.background(Color.black.ignoresSafeArea())
	38	.foregroundStyle(ink)
	39	.navigationTitle(path.map { "\($0.kind) solar eclipse" } ?? "Solar eclipse")
	40	.navigationBarTitleDisplayMode(.inline)
	41	.toolbar { ToolbarItem(placement: .confirmationAction) { Button("Done") { dismiss() } } }
	42	}
	43	.task {
	44	let date = date, observer = observer
	45	(path, local) = await Task.detached { (EclipsePath.compute(near: date), LocalEclipse.at(observer, near: date)) }.value
	46	loaded = true
	47	}
	48	}
	49
	50	private func facts(_ p: EclipsePath) -> some View {
	51	let middle = p.points.min { abs($0.date.timeIntervalSince(p.peak)) < abs($1.date.timeIntervalSince(p.peak)) }
	52	var rows: [(String, String)] = [
	53	("Date", p.peak.formatted(date: .long, time: .omitted)),
	54	("Greatest eclipse", "\(p.peak.formatted(date: .omitted, time: .shortened)) at \(latLon(p.greatest))"),
	55	]
	56	if let d = p.centralDuration { rows.append(("\(p.kind == "Total" ? "Totality" : "Annularity") there", minutes(d))) }
	57	if let m = middle { rows.append(("Path width there", "\(Int(m.widthKm.rounded())) km")) }
	58	return Grid(alignment: .leading, horizontalSpacing: 16, verticalSpacing: 6) {
	59	ForEach(rows, id: \.0) { r in
	60	GridRow { Text(r.0).dimmed(0.7); Text(r.1).monospacedDigit() }.font(.subheadline)
	61	}
	62	}
	63	}
	64
	65	@ViewBuilder
	66	private var here: some View {
	67	VStack(alignment: .leading, spacing: 6) {
	68	Text("From \(placeName)").font(.caption2.weight(.medium)).textCase(.uppercase).tracking(0.8).dimmed(0.6)
	69	if let l = local {
	70	let central = l.kind == "Total" ? "Totality" : "Annular phase"
	71	Grid(alignment: .leading, horizontalSpacing: 16, verticalSpacing: 6) {
	72	GridRow { Text("Begins").dimmed(0.7); Text(time(l.partialBegin)) }
	73	if let b = l.centralBegin, let e = l.centralEnd {
	74	GridRow { Text(central).dimmed(0.7); Text("\(time(b))–\(time(e)), \(minutes(e.timeIntervalSince(b)))") }
	75	}
	76	GridRow { Text("Maximum").dimmed(0.7); Text("\(time(l.peak)), \(Int((l.obscuration * 100).rounded()))% of the Sun covered") }
	77	GridRow { Text("Ends").dimmed(0.7); Text(time(l.partialEnd)) }
	78	}
	79	.font(.subheadline.monospacedDigit())
	80	if l.peakAltitude < 10 {
	81	Text("The Sun is low at maximum (\(Int(l.peakAltitude.rounded()))°). Find a clear horizon.").font(.footnote).dimmed(0.7)
	82	}
	83	} else {
	84	Text("Not visible from here.").font(.subheadline).dimmed(0.7)
	85	}
	86	Text("Never look at the Sun without certified eclipse glasses, except during totality itself.")
	87	.font(.footnote).foregroundStyle(accent).padding(.top, 6)
	88	}
	89	}
	90
	91	private func time(_ d: Date) -> String { d.formatted(date: .omitted, time: .standard) }
	92
	93	private func minutes(_ s: TimeInterval) -> String { "\(Int(s) / 60) m \(Int(s) % 60) s" }
	94
	95	private func latLon(_ p: (lat: Double, lon: Double)) -> String {
	96	String(format: "%.1f°%@, %.1f°%@", abs(p.lat), p.lat >= 0 ? "N" : "S", abs(p.lon), p.lon >= 0 ? "E" : "W")
	97	}
	98	}
	99
	100	/// Equirectangular map around the path: coastlines, the band between the limits, and the centre line.
	101	struct EclipseMap: View {
	102	var path: EclipsePath
	103	var observer: Observer
	104	var ink: Color
	105	var accent: Color
	106
	107	var body: some View {
	108	Canvas { context, size in
	109	let centers = path.points.map(\.center)
	110	let lats = centers.map(\.lat), lons = centers.map(\.lon)
	111	let latRange = (lats.min()! - 8)...(lats.max()! + 8)
	112	let lonRange = (lons.min()! - 10)...(lons.max()! + 10)
	113	func pt(_ lat: Double, _ lon: Double) -> CGPoint {
	114	CGPoint(x: (lon - lonRange.lowerBound) / (lonRange.upperBound - lonRange.lowerBound) * size.width,
	115	y: (latRange.upperBound - lat) / (latRange.upperBound - latRange.lowerBound) * size.height)
	116	}
	117
	118	context.fill(Path(CGRect(origin: .zero, size: size)), with: .color(ink.opacity(0.04)))
	119	var grid = Path()
	120	for lat in stride(from: -80.0, through: 80, by: 10) where latRange.contains(lat) {
	121	grid.move(to: pt(lat, lonRange.lowerBound)); grid.addLine(to: pt(lat, lonRange.upperBound))
	122	}
	123	for lon in stride(from: -180.0, through: 180, by: 10) where lonRange.contains(lon) {
	124	grid.move(to: pt(latRange.lowerBound, lon)); grid.addLine(to: pt(latRange.upperBound, lon))
	125	}
	126	context.stroke(grid, with: .color(ink.opacity(0.08)), lineWidth: 0.5)
	127
	128	var coast = Path()
	129	for line in Coastline.lines {
	130	var pen = false
	131	for p in line {
	132	let q = pt(p.lat, p.lon)
	133	if pen { coast.addLine(to: q) } else { coast.move(to: q); pen = true }
	134	}
	135	}
	136	context.stroke(coast, with: .color(ink.opacity(0.55)), lineWidth: 0.8)
	137
	138	let limits = path.points.compactMap { p in p.north.flatMap { n in p.south.map { (n, $0) } } }
	139	if limits.count > 1 {
	140	var band = Path()
	141	band.move(to: pt(limits[0].0.lat, limits[0].0.lon))
	142	for l in limits.dropFirst() { band.addLine(to: pt(l.0.lat, l.0.lon)) }
	143	for l in limits.reversed() { band.addLine(to: pt(l.1.lat, l.1.lon)) }
	144	band.closeSubpath()
	145	context.fill(band, with: .color(accent.opacity(0.4)))
	146	}
	147	var center = Path()
	148	center.addLines(centers.map { pt($0.lat, $0.lon) })
	149	context.stroke(center, with: .color(accent), lineWidth: 1.2)
	150
	151	let g = pt(path.greatest.lat, path.greatest.lon)
	152	context.stroke(Path(ellipseIn: CGRect(x: g.x - 5, y: g.y - 5, width: 10, height: 10)), with: .color(ink), lineWidth: 1.5)
	153	if latRange.contains(observer.latitude), lonRange.contains(observer.longitude) {
	154	let o = pt(observer.latitude, observer.longitude)
	155	context.fill(Path(ellipseIn: CGRect(x: o.x - 4, y: o.y - 4, width: 8, height: 8)), with: .color(ink))
	156	context.draw(Text("You").font(.caption2).foregroundStyle(ink), at: CGPoint(x: o.x, y: o.y - 11))
	157	}
	158	}
	159	.overlay(alignment: .bottomLeading) {
	160	Text("Shaded: where the eclipse is \(path.kind.lowercased()). Ring: greatest eclipse.")
	161	.font(.caption2).dimmed(0.7).padding(6)
	162	}
	163	}
	164	}

App/Sources/EventsScreen.swift +11 −1

		@@ -7,6 +7,7 @@ struct EventsScreen: View {
7	7	var placeName: String
8	8	@State private var events: [SkyEvent] = []
9	9	@State private var filter = "notable"
	10	@State private var eclipse: SkyEvent?
10	11	@Environment(\.dismiss) private var dismiss
11	12
12	13	private let ink = Color(red: 0.95, green: 0.95, blue: 0.93)
		@@ -39,7 +40,15 @@ struct EventsScreen: View {
39	40	}
40	41	ForEach(months, id: \.0) { month, items in
41	42	Section(month) {
42		ForEach(items) { row($0) }
	43	ForEach(items) { e in
	44	if e.kind == .solarEclipse {
	45	Button { eclipse = e } label: { row(e) }
	46	.buttonStyle(.plain)
	47	.accessibilityHint("Shows the path and local times")
	48	} else {
	49	row(e)
	50	}
	51	}
43	52	}
44	53	}
45	54	}
		@@ -49,6 +58,7 @@ struct EventsScreen: View {
49	58	.navigationTitle("Events")
50	59	.navigationBarTitleDisplayMode(.inline)
51	60	.toolbar { ToolbarItem(placement: .confirmationAction) { Button("Done") { dismiss() } } }
	61	.sheet(item: $eclipse) { e in EclipseScreen(date: e.date, observer: observer, placeName: placeName) }
52	62	}
53	63	.foregroundStyle(ink)
54	64	.task {

PLAN.org +1

		@@ -393,6 +393,7 @@ Sky, System, Sun, Launches, Library core (above).
393	393	- Events: eclipses, meteor showers, conjunctions, oppositions, each with
394	394	an observing plan. Eclipse path maps with local timings; the 2 August
395	395	2027 total eclipse (Spain, North Africa, Egypt) is a launch target.
	396	Path maps and local timings done for every total and annular eclipse.
396	397	- Deep Space Network Now: which DSN dishes are talking to which
397	398	spacecraft.
398	399	- More satellites: Tiangong, Hubble, Starlink trains, bright passes. Done:

Packages/MoonriseKit/Sources/SkyEngine/EclipsePath.swift added +154

		@@ -0,0 +1,154 @@
	1	import CAstronomy
	2	import Foundation
	3
	4	/// Ground track of the Moon's umbra (total) or antumbra (annular) for one solar eclipse,
	5	/// from the Sun–Moon shadow axis intersected with the Earth's ellipsoid.
	6	public struct EclipsePath: Sendable {
	7	public struct Point: Sendable, Equatable {
	8	public var date: Date
	9	public var center: (lat: Double, lon: Double)
	10	public var north: (lat: Double, lon: Double)?
	11	public var south: (lat: Double, lon: Double)?
	12	/// Width of the path at this point, km.
	13	public var widthKm: Double
	14
	15	public static func == (a: Point, b: Point) -> Bool { a.date == b.date }
	16	}
	17
	18	public var kind: String
	19	public var peak: Date
	20	/// Greatest eclipse.
	21	public var greatest: (lat: Double, lon: Double)
	22	/// Duration of totality or annularity at greatest eclipse, seconds.
	23	public var centralDuration: TimeInterval?
	24	public var points: [Point]
	25
	26	static let sunRadiusKm = 695_700.0
	27	static let moonRadiusKm = 1_737.4
	28	static let earthA = 6_378.137
	29	static let earthF = 1 / 298.257223563
	30	static let kmPerAU = 1.495978707e8
	31
	32	/// The path of the first total or annular eclipse whose peak is within a day of `date`.
	33	public static func compute(near date: Date, step: TimeInterval = 60) -> EclipsePath? {
	34	SkyEngine.lock.lock()
	35	defer { SkyEngine.lock.unlock() }
	36	let g = Astronomy_SearchGlobalSolarEclipse(SkyEngine.time(date.addingTimeInterval(-86_400)))
	37	guard g.status == ASTRO_SUCCESS, g.kind == ECLIPSE_TOTAL \|\| g.kind == ECLIPSE_ANNULAR else { return nil }
	38	let peak = SkyEngine.date(g.peak)
	39	guard abs(peak.timeIntervalSince(date)) < 86_400 else { return nil }
	40
	41	var points: [Point] = []
	42	var t = peak.addingTimeInterval(-4 * 3600)
	43	while t <= peak.addingTimeInterval(4 * 3600) {
	44	if let p = point(at: t, step: step) { points.append(p) }
	45	t = t.addingTimeInterval(step)
	46	}
	47
	48	let at = Observer(latitude: g.latitude, longitude: g.longitude)
	49	let local = Astronomy_SearchLocalSolarEclipse(SkyEngine.time(peak.addingTimeInterval(-6 * 3600)), at.astro)
	50	var duration: TimeInterval?
	51	if local.status == ASTRO_SUCCESS, local.kind == g.kind {
	52	duration = SkyEngine.date(local.total_end.time).timeIntervalSince(SkyEngine.date(local.total_begin.time))
	53	}
	54	return EclipsePath(kind: SkyEngine.eclipseKind(g.kind), peak: peak, greatest: (g.latitude, g.longitude), centralDuration: duration, points: points)
	55	}
	56
	57	/// Centre and limits of the path at `date`, or nil if the shadow axis misses the Earth.
	58	static func point(at date: Date, step: TimeInterval) -> Point? {
	59	guard let (center, n, r) = axis(at: date), let next = axis(at: date.addingTimeInterval(step)) else { return nil }
	60	guard let c = center.hit, let c2 = next.0.hit else { return nil }
	61	// Unit vector across the track: perpendicular to the shadow axis and the ground motion.
	62	let across = normalize(cross(n, c2 - c))
	63	let offset = across * (abs(r) / kmPerAU)
	64	let north = Ray(origin: center.origin + offset, direction: n).hit
	65	let south = Ray(origin: center.origin - offset, direction: n).hit
	66	let t = SkyEngine.time(date)
	67	func geo(_ v: SIMD3<Double>) -> (lat: Double, lon: Double) {
	68	var vec = astro_vector_t(status: ASTRO_SUCCESS, x: v.x, y: v.y, z: v.z, t: t)
	69	let o = Astronomy_VectorObserver(&vec, EQUATOR_OF_DATE)
	70	return (o.latitude, o.longitude)
	71	}
	72	var a = geo(north ?? c), b = geo(south ?? c)
	73	if a.lat < b.lat { swap(&a, &b) }
	74	let width = (north != nil && south != nil) ? length(north! - south!) * kmPerAU : 2 * abs(r)
	75	return Point(date: date, center: geo(c), north: north == nil ? nil : a, south: south == nil ? nil : b, widthKm: width)
	76	}
	77
	78	struct Ray {
	79	var origin: SIMD3<Double>
	80	var direction: SIMD3<Double>
	81
	82	/// First intersection with the Earth's ellipsoid, AU, equator-of-date axes.
	83	var hit: SIMD3<Double>? {
	84	let k = 1 / (1 - EclipsePath.earthF)
	85	let o = SIMD3(origin.x, origin.y, origin.z * k), d = SIMD3(direction.x, direction.y, direction.z * k)
	86	let a = EclipsePath.earthA / EclipsePath.kmPerAU
	87	let A = dot(d, d), B = 2 * dot(o, d), C = dot(o, o) - a * a
	88	let disc = B * B - 4 * A * C
	89	guard disc >= 0 else { return nil }
	90	let s = (-B - disc.squareRoot()) / (2 * A)
	91	guard s > 0 else { return nil }
	92	let p = o + d * s
	93	return SIMD3(p.x, p.y, p.z / k)
	94	}
	95	}
	96
	97	/// Shadow axis from the Moon away from the Sun (equator of date), its direction,
	98	/// and the umbra radius where it meets the Earth (km; negative for the antumbra).
	99	static func axis(at date: Date) -> (Ray, SIMD3<Double>, Double)? {
	100	var t = SkyEngine.time(date)
	101	let rot = Astronomy_Rotation_EQJ_EQD(&t)
	102	let sun = Astronomy_RotateVector(rot, Astronomy_GeoVector(BODY_SUN, t, NO_ABERRATION))
	103	let moon = Astronomy_RotateVector(rot, Astronomy_GeoMoon(t))
	104	let s = SIMD3(sun.x, sun.y, sun.z), m = SIMD3(moon.x, moon.y, moon.z)
	105	let n = normalize(m - s)
	106	let ray = Ray(origin: m, direction: n)
	107	guard let hit = ray.hit else { return nil }
	108	let D = length(m - s) * kmPerAU
	109	let L = length(hit - m) * kmPerAU
	110	let r = moonRadiusKm - L * (sunRadiusKm - moonRadiusKm) / D
	111	return (ray, n, r)
	112	}
	113	}
	114
	115	private func dot(_ a: SIMD3<Double>, _ b: SIMD3<Double>) -> Double { (a * b).sum() }
	116	private func length(_ a: SIMD3<Double>) -> Double { dot(a, a).squareRoot() }
	117	private func normalize(_ a: SIMD3<Double>) -> SIMD3<Double> { a / length(a) }
	118	private func cross(_ a: SIMD3<Double>, _ b: SIMD3<Double>) -> SIMD3<Double> {
	119	SIMD3(a.y * b.z - a.z * b.y, a.z * b.x - a.x * b.z, a.x * b.y - a.y * b.x)
	120	}
	121
	122	/// A solar eclipse as seen from one place.
	123	public struct LocalEclipse: Sendable {
	124	public var kind: String
	125	public var obscuration: Double
	126	public var partialBegin: Date
	127	public var centralBegin: Date?
	128	public var peak: Date
	129	public var centralEnd: Date?
	130	public var partialEnd: Date
	131	/// Sun's altitude at the peak, degrees.
	132	public var peakAltitude: Double
	133
	134	/// The observer's view of the solar eclipse peaking within six hours of `date`, if any part is above the horizon.
	135	public static func at(_ observer: Observer, near date: Date) -> LocalEclipse? {
	136	SkyEngine.lock.lock()
	137	defer { SkyEngine.lock.unlock() }
	138	let l = Astronomy_SearchLocalSolarEclipse(SkyEngine.time(date.addingTimeInterval(-6 * 3600)), observer.astro)
	139	guard l.status == ASTRO_SUCCESS else { return nil }
	140	let peak = SkyEngine.date(l.peak.time)
	141	guard abs(peak.timeIntervalSince(date)) < 6 * 3600 else { return nil }
	142	guard l.partial_begin.altitude > 0 \|\| l.peak.altitude > 0 \|\| l.partial_end.altitude > 0 else { return nil }
	143	let central = l.kind == ECLIPSE_TOTAL \|\| l.kind == ECLIPSE_ANNULAR
	144	return LocalEclipse(
	145	kind: SkyEngine.eclipseKind(l.kind), obscuration: l.obscuration,
	146	partialBegin: SkyEngine.date(l.partial_begin.time),
	147	centralBegin: central ? SkyEngine.date(l.total_begin.time) : nil,
	148	peak: peak,
	149	centralEnd: central ? SkyEngine.date(l.total_end.time) : nil,
	150	partialEnd: SkyEngine.date(l.partial_end.time),
	151	peakAltitude: l.peak.altitude
	152	)
	153	}
	154	}

Packages/MoonriseKit/Tests/SkyEngineTests/EclipsePathTests.swift added +47

		@@ -0,0 +1,47 @@
	1	import Foundation
	2	import Testing
	3	@testable import SkyEngine
	4
	5	/// Distance in km between two points on a sphere.
	6	private func km(_ a: (lat: Double, lon: Double), _ b: (lat: Double, lon: Double)) -> Double {
	7	let r = Double.pi / 180
	8	let h = pow(sin((b.lat - a.lat) * r / 2), 2) + cos(a.lat * r) * cos(b.lat * r) * pow(sin((b.lon - a.lon) * r / 2), 2)
	9	return 2 * 6371 * asin(h.squareRoot())
	10	}
	11
	12	@Test func totalEclipse2027Path() throws {
	13	// NASA (Espenak): greatest eclipse 2027-08-02 10:07 UT at 25.5° N, 33.2° E,
	14	// totality 6 m 23 s, path 258 km wide; the path crosses southern Spain and Luxor.
	15	let path = try #require(EclipsePath.compute(near: Date(timeIntervalSince1970: 1_817_201_220)))
	16	#expect(path.kind == "Total")
	17	#expect(abs(path.greatest.lat - 25.5) < 0.3 && abs(path.greatest.lon - 33.2) < 0.3)
	18	let duration = try #require(path.centralDuration)
	19	#expect(abs(duration - 383) < 5)
	20	#expect(path.points.count > 100)
	21
	22	func nearest(_ place: (lat: Double, lon: Double)) -> Double {
	23	path.points.map { km($0.center, place) }.min()!
	24	}
	25	#expect(nearest((25.69, 32.64)) < 40) // Luxor, close to the centre line
	26	#expect(nearest((36.01, -5.60)) < 120) // Tarifa, inside the path
	27
	28	let middle = path.points.min { abs($0.date.timeIntervalSince(path.peak)) < abs($1.date.timeIntervalSince(path.peak)) }!
	29	#expect(abs(middle.widthKm - 258) < 20)
	30	}
	31
	32	@Test func noPathForPartialEclipse() {
	33	// 21 September 2025 was partial only.
	34	#expect(EclipsePath.compute(near: Date(timeIntervalSince1970: 1_758_483_660)) == nil)
	35	}
	36
	37	@Test func localCircumstances2027() throws {
	38	let peak = Date(timeIntervalSince1970: 1_817_201_220)
	39	let luxor = try #require(LocalEclipse.at(Observer(latitude: 25.69, longitude: 32.64), near: peak))
	40	#expect(luxor.kind == "Total")
	41	let begin = try #require(luxor.centralBegin), end = try #require(luxor.centralEnd)
	42	#expect(end.timeIntervalSince(begin) > 360)
	43	let madrid = try #require(LocalEclipse.at(Observer(latitude: 40.42, longitude: -3.70), near: peak))
	44	#expect(madrid.kind == "Partial" && madrid.centralBegin == nil)
	45	#expect(madrid.obscuration > 0.8 && madrid.obscuration < 0.95)
	46	#expect(LocalEclipse.at(Observer(latitude: 41.88, longitude: -87.63), near: peak) == nil) // Chicago: night
	47	}

Commit 5395f2f431

Commit `5395f2f431`