这里我截取的是一个图片，实际上是会动的。废话不多说，上代码。
HTML：

<canvas id="canvas"></canvas>

CSS：

/*css reset */
body,p,div,ol,ul,li,dl,dt,dd,h1,h2,h3,h4,h5,h6,form,input,iframe,nav {margin: 0;padding: 0;
}
html,body {width: 100%;height: 100%;
}
body {font: 14px Microsoft YaHei;-webkit-text-size-adjust:100%;-moz-user-select: none;-webkit-user-select: none;user-select: none;position: relative;background: #000;
}#canvas {width: 100%;height: 100%;display: block;opacity: .8;
}

JS：

// 音量大小,0.01-1//宇宙特效
var canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d'),
w = canvas.width = window.innerWidth,
h = canvas.height = window.innerHeight,hue = 217,
stars = [],
count = 0,
maxStars = 1100;                //星星数量,默认1300
var canvas2 = document.createElement('canvas'),
ctx2 = canvas2.getContext('2d');
canvas2.width = 100;
canvas2.height = 100;
var half = canvas2.width / 2,
gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half);
gradient2.addColorStop(0.025, '#CCC');
gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)');
gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)');
gradient2.addColorStop(1, 'transparent');ctx2.fillStyle = gradient2;
ctx2.beginPath();
ctx2.arc(half, half, half, 0, Math.PI * 2);
ctx2.fill();// End cache
function random(min, max) {if (arguments.length < 2) {max = min;min = 0;}if (min > max) {var hold = max;max = min;min = hold;}return Math.floor(Math.random() * (max - min + 1)) + min;
}function maxOrbit(x, y) {var max = Math.max(x, y),diameter = Math.round(Math.sqrt(max * max + max * max));return diameter / 2;//星星移动范围，值越大范围越小，
}var Star = function() {this.orbitRadius = random(maxOrbit(w, h));this.radius = random(60, this.orbitRadius) / 10;       //星星大小,值越大星星越小,默认8this.orbitX = w / 2;this.orbitY = h / 2;this.timePassed = random(0, maxStars);this.speed = random(this.orbitRadius) / 80000;        //星星移动速度,值越大越慢,默认5Wthis.alpha = random(2, 10) / 10;count++;stars[count] = this;
}Star.prototype.draw = function() {var x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX,y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY,twinkle = random(10);if (twinkle === 1 && this.alpha > 0) {this.alpha -= 0.05;} else if (twinkle === 2 && this.alpha < 1) {this.alpha += 0.05;}ctx.globalAlpha = this.alpha;ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius);this.timePassed += this.speed;
}for (var i = 0; i < maxStars; i++) {new Star();
}function animation() {ctx.globalCompositeOperation = 'source-over';ctx.globalAlpha = 0.5;                                 //尾巴ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 2)';ctx.fillRect(0, 0, w, h)ctx.globalCompositeOperation = 'lighter';for (var i = 1,l = stars.length; i < l; i++) {stars[i].draw();};window.requestAnimationFrame(animation);
}animation();