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<html lang="en"> | |
<head> | |
<meta charset="UTF-8"> | |
<meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
<title>Why We See Only One Side of the Moon</title> | |
<!-- Fonts for header and body --> | |
<link href="https://fonts.googleapis.com/css2?family=Inter:wght@400;700&family=Space+Grotesk:wght@700&display=swap" rel="stylesheet"> | |
<script src="https://cdn.tailwindcss.com"></script> | |
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.9.0/p5.min.js"></script> | |
<style> | |
html, body, .font-sans { | |
font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, "Noto Sans", sans-serif; | |
} | |
body { | |
margin: 0; | |
padding: 0; | |
overflow: hidden; | |
} | |
#animation-container { | |
position: relative; | |
width: 100vw; | |
height: 100vh; | |
overflow: hidden; | |
background-color: #000010; | |
} | |
#animation-canvas { | |
display: block; | |
position: absolute; | |
top: 0; | |
left: 0; | |
z-index: 1; | |
} | |
.header-astro { | |
font-family: 'Space Grotesk', 'Inter', Arial, sans-serif; | |
font-weight: 700; | |
letter-spacing: -0.01em; | |
} | |
.control-panel { | |
position: absolute; | |
bottom: 2rem; | |
left: 2rem; | |
z-index: 10; | |
background: rgba(0, 0, 20, 0.7); | |
backdrop-filter: blur(10px); | |
border-radius: 1rem; | |
padding: 1rem; | |
box-shadow: 0 0 20px rgba(186, 215, 255, 0.2); | |
display: flex; | |
flex-direction: column; | |
gap: 0.5rem; | |
} | |
.explanation-panel { | |
position: absolute; | |
top: 2rem; | |
right: 2rem; | |
z-index: 10; | |
background: rgba(0, 0, 20, 0.7); | |
backdrop-filter: blur(10px); | |
border-radius: 1rem; | |
padding: 1.5rem; | |
box-shadow: 0 0 20px rgba(186, 215, 255, 0.2); | |
color: white; | |
width: 220px; | |
font-size: 1rem; | |
line-height: 1.6; | |
transition: opacity 0.3s ease-in-out; | |
opacity: 0; | |
} | |
.control-btn { | |
padding: 0.5rem 1rem; | |
font-size: 0.92rem; | |
font-weight: 600; | |
color: white; | |
background-color: rgba(255, 255, 255, 0.1); | |
border: 1px solid rgba(255, 255, 255, 0.2); | |
border-radius: 0.5rem; | |
cursor: pointer; | |
transition: background-color 0.2s ease; | |
text-align: center; | |
font-family: 'Inter', system-ui, sans-serif; | |
} | |
.control-btn:hover { | |
background-color: rgba(255, 255, 255, 0.2); | |
} | |
.control-btn.active { | |
background-color: #4f46e5; | |
border-color: #4f46e5; | |
} | |
/* Disclaimer at bottom, single line, smaller, no glow */ | |
.disclaimer-line { | |
position: fixed; | |
left: 50%; | |
bottom: 1.1rem; | |
transform: translateX(-50%); | |
z-index: 40; | |
font-size: 0.89rem; | |
color: #b6bed7; | |
font-family: 'Inter', system-ui, sans-serif; | |
text-align: center; | |
padding: 0 0.5rem; | |
border-radius: 0.4rem; | |
pointer-events: none; | |
white-space: nowrap; | |
background: transparent; | |
opacity: 0.88; | |
} | |
</style> | |
</head> | |
<body class="bg-black text-white overflow-hidden font-sans"> | |
<div id="animation-container" class="relative"> | |
<h1 class="header-astro absolute text-center top-8 left-1/2 -translate-x-1/2 text-3xl md:text-4xl font-bold text-white z-20 w-11/12" style="text-shadow: 0 0 15px rgba(186, 215, 255, 0.7);"> | |
Why We See Only One Side of the Moon | |
</h1> | |
<!-- Canvas will be inserted here by p5.js --> | |
</div> | |
<div id="explanation-panel" class="explanation-panel"></div> | |
<div class="control-panel"> | |
<button id="btn-no-rotation" class="control-btn">No Rotation</button> | |
<button id="btn-fast-rotation" class="control-btn">Fast Rotation</button> | |
<button id="btn-locked-rotation" class="control-btn active">Tidally Locked</button> | |
</div> | |
<div class="disclaimer-line"> | |
Disclaimer: Earth’s rotation is hidden to keep the focus on the Moon’s motion. | |
</div> | |
<script> | |
document.addEventListener('DOMContentLoaded', () => { | |
const sketch = (p) => { | |
let earth; | |
let moon; | |
let stars = []; | |
let rotationMode = 'locked'; | |
let starCount = 800; | |
const btnNoRotation = document.getElementById('btn-no-rotation'); | |
const btnFastRotation = document.getElementById('btn-fast-rotation'); | |
const btnLockedRotation = document.getElementById('btn-locked-rotation'); | |
const explanationPanel = document.getElementById('explanation-panel'); | |
const explanations = { | |
none: '<strong>No Rotation:</strong> The Moon does not spin on its own axis. The red line always points in the same direction, so we see all sides of the Moon as it orbits.', | |
fast: '<strong>Fast Rotation:</strong> The Moon spins on its own axis very quickly, much faster than it orbits the Earth. We can easily see all of its sides.', | |
locked: '<strong>Tidally Locked:</strong> The Moon rotates on its axis at the same speed it orbits the Earth. This is why the red line (and the same face) always points toward the Earth!' | |
}; | |
function updateActiveButton() { | |
document.querySelectorAll('.control-btn').forEach(btn => btn.classList.remove('active')); | |
explanationPanel.style.opacity = '1'; | |
if (rotationMode === 'none') { | |
btnNoRotation.classList.add('active'); | |
explanationPanel.innerHTML = explanations.none; | |
} else if (rotationMode === 'fast') { | |
btnFastRotation.classList.add('active'); | |
explanationPanel.innerHTML = explanations.fast; | |
} else if (rotationMode === 'locked') { | |
btnLockedRotation.classList.add('active'); | |
explanationPanel.innerHTML = explanations.locked; | |
} | |
} | |
btnNoRotation.addEventListener('click', () => { | |
rotationMode = 'none'; | |
updateActiveButton(); | |
}); | |
btnFastRotation.addEventListener('click', () => { | |
rotationMode = 'fast'; | |
updateActiveButton(); | |
}); | |
btnLockedRotation.addEventListener('click', () => { | |
rotationMode = 'locked'; | |
updateActiveButton(); | |
}); | |
function fillStars(n) { | |
stars = []; | |
for (let i = 0; i < n; i++) { | |
stars.push(p.createVector(p.random(p.width), p.random(p.height))); | |
} | |
} | |
p.setup = () => { | |
let canvas = p.createCanvas(p.windowWidth, p.windowHeight); | |
canvas.parent('animation-container'); | |
canvas.id('animation-canvas'); | |
p.colorMode(p.HSB, 360, 100, 100, 100); | |
p.angleMode(p.DEGREES); | |
earth = new Earth(p.width / 2, p.height / 2); | |
moon = new Moon(earth.pos.x, earth.pos.y, p.min(p.width, p.height) * 0.4); | |
starCount = Math.floor((p.width * p.height) / 1800); | |
fillStars(starCount); | |
updateActiveButton(); | |
}; | |
p.draw = () => { | |
p.background(245, 90, 10); | |
drawStars(); | |
moon.update(); | |
earth.update(); | |
earth.display(moon.pos); | |
moon.display(); | |
}; | |
function drawStars() { | |
p.noStroke(); | |
for (const star of stars) { | |
star.x -= 0.02; | |
if (star.x < 0) { | |
star.x = p.width; | |
} | |
let alpha = p.random(50, 100); | |
let size = p.random(1, 3); | |
if (p.random() > 0.99) { | |
alpha = 100; | |
size = p.random(2.5, 4); | |
} | |
p.fill(0, 0, 100, alpha); | |
p.ellipse(star.x, star.y, size, size); | |
} | |
} | |
p.windowResized = () => { | |
p.resizeCanvas(p.windowWidth, p.windowHeight); | |
if (earth) earth.pos.set(p.width / 2, p.height / 2); | |
if (moon) { | |
moon.center.set(p.width / 2, p.height / 2); | |
moon.radius = p.min(p.width, p.height) * 0.35; | |
} | |
starCount = Math.floor((p.width * p.height) / 1800); | |
fillStars(starCount); | |
}; | |
class Earth { | |
constructor(x, y) { | |
this.pos = p.createVector(x, y); | |
this.bodySize = p.min(p.width, p.height) * 0.25; | |
this.eyes = [ | |
{ offset: p.createVector(-this.bodySize * 0.27, -this.bodySize * 0.13), size: this.bodySize * 0.25 }, | |
{ offset: p.createVector(this.bodySize * 0.27, -this.bodySize * 0.13), size: this.bodySize * 0.25 } | |
]; | |
} | |
update() { | |
this.bodySize = p.min(p.width, p.height) * 0.25; | |
this.eyes[0].offset.set(-this.bodySize * 0.27, -this.bodySize * 0.13); | |
this.eyes[1].offset.set(this.bodySize * 0.27, -this.bodySize * 0.13); | |
this.eyes[0].size = this.bodySize * 0.25; | |
this.eyes[1].size = this.bodySize * 0.25; | |
} | |
display(target) { | |
p.push(); | |
p.translate(this.pos.x, this.pos.y); | |
p.drawingContext.shadowBlur = 60; | |
p.drawingContext.shadowColor = p.color(200, 80, 100, 50); | |
p.fill(210, 80, 80); | |
p.noStroke(); | |
p.ellipse(0, 0, this.bodySize, this.bodySize); | |
p.fill(120, 60, 65); | |
p.noStroke(); | |
p.beginShape(); | |
p.curveVertex(this.bodySize * -0.15, this.bodySize * -0.4); | |
p.curveVertex(this.bodySize * -0.1, this.bodySize * -0.4); | |
p.curveVertex(this.bodySize * -0.2, this.bodySize * -0.2); | |
p.curveVertex(this.bodySize * -0.15, 0.05); | |
p.curveVertex(this.bodySize * -0.3, this.bodySize * 0.3); | |
p.curveVertex(this.bodySize * -0.2, this.bodySize * 0.45); | |
p.curveVertex(this.bodySize * 0.05, this.bodySize * 0.4); | |
p.curveVertex(this.bodySize * 0.1, 0.1); | |
p.curveVertex(this.bodySize * -0.1, this.bodySize * -0.4); | |
p.curveVertex(this.bodySize * -0.1, this.bodySize * -0.4); | |
p.endShape(p.CLOSE); | |
p.beginShape(); | |
p.curveVertex(this.bodySize * 0.4, this.bodySize * -0.3); | |
p.curveVertex(this.bodySize * 0.45, this.bodySize * -0.2); | |
p.curveVertex(this.bodySize * 0.35, 0); | |
p.curveVertex(this.bodySize * 0.4, this.bodySize * 0.25); | |
p.curveVertex(this.bodySize * 0.2, this.bodySize * 0.4); | |
p.curveVertex(this.bodySize * 0.15, this.bodySize * 0.2); | |
p.curveVertex(this.bodySize * 0.25, 0); | |
p.endShape(p.CLOSE); | |
p.fill(200, 5, 100, 90); | |
p.noStroke(); | |
p.arc(0, 0, this.bodySize, this.bodySize, 250, 290, p.CHORD); | |
p.arc(0, 0, this.bodySize, this.bodySize, 70, 110, p.CHORD); | |
p.drawingContext.shadowBlur = 0; | |
this.eyes.forEach(eye => this.drawEye(eye.offset.x, eye.offset.y, eye.size, target)); | |
p.noFill(); | |
p.stroke(210, 20, 20, 80); | |
p.strokeWeight(4); | |
p.arc(0, this.bodySize * 0.15, this.bodySize * 0.4, this.bodySize * 0.27, 0, 180); | |
p.pop(); | |
} | |
drawEye(x, y, size, target) { | |
let eyePos = p.createVector(this.pos.x + x, this.pos.y + y); | |
let angle = p.atan2(target.y - eyePos.y, target.x - eyePos.x); | |
let dist = p5.Vector.dist(target, eyePos); | |
let pupilOffset = p.min(dist, size / 2 - (size / 1.8 / 2)); | |
p.push(); | |
p.translate(x, y); | |
p.stroke(200, 10, 20, 80); | |
p.strokeWeight(2); | |
p.fill(200, 5, 100); | |
p.ellipse(0, 0, size, size); | |
p.rotate(angle); | |
p.noStroke(); | |
p.fill(0); | |
p.ellipse(pupilOffset, 0, size / 1.8, size / 1.8); | |
p.pop(); | |
} | |
} | |
class Moon { | |
constructor(centerX, centerY, radius) { | |
this.center = p.createVector(centerX, centerY); | |
this.radius = radius; | |
this.size = p.min(p.width, p.height) * 0.08; | |
this.orbitalAngle = 0; | |
this.selfRotationAngle = 0; | |
this.speed = 0.5; | |
this.pos = p.createVector(); | |
} | |
update() { | |
this.size = p.min(p.width, p.height) * 0.08; | |
this.orbitalAngle += this.speed; | |
this.selfRotationAngle += 4; | |
this.pos.x = this.center.x + this.radius * p.cos(this.orbitalAngle); | |
this.pos.y = this.center.y + this.radius * p.sin(this.orbitalAngle); | |
} | |
display() { | |
p.noFill(); | |
p.stroke(100, 0, 100, 10); | |
p.strokeWeight(1); | |
p.ellipse(this.center.x, this.center.y, this.radius * 2, this.radius * 2); | |
p.push(); | |
p.translate(this.pos.x, this.pos.y); | |
if (rotationMode === 'locked') { | |
let angleToEarth = p.atan2(this.center.y - this.pos.y, this.center.x - this.pos.x); | |
p.rotate(angleToEarth); | |
} else if (rotationMode === 'fast') { | |
p.rotate(this.selfRotationAngle); | |
} | |
p.fill(0, 0, 50); | |
p.noStroke(); | |
p.arc(0, 0, this.size, this.size, 90, 270); | |
p.fill(0, 0, 85); | |
p.arc(0, 0, this.size, this.size, -90, 90); | |
p.stroke(0, 100, 100); | |
p.strokeWeight(3); | |
p.line(0, -this.size * 0.5, 0, this.size * 0.5); | |
p.pop(); | |
} | |
} | |
}; | |
new p5(sketch); | |
}); | |
</script> | |
</body> | |
</html> | |