index.js

var stage = new Konva.Stage({
    container: 'dibujo',
    width: 556,
    height: 316
});

function crearAnimacion(star){
    var anim = new Konva.Animation(function(frame) {
        var scale = Math.sin(frame.time * 2.5 * Math.PI / 2000) + 0.001;
        star.scale({ x :scale, y : scale});
        var angleDiff = frame.timeDiff * 90/ 1000;
        star.rotate(angleDiff);
    }, layer);
    anim.start();
}

function crearEstrella(){
    var sX, sY;
    sX = sY = Math.random();

    return new Konva.Star({
        x: Math.floor(Math.random() * 556),
        y: Math.floor(Math.random() * 316),
        numPoints: 5,
        innerRadius: 40,
        outerRadius: 80,
        rotation: Math.floor(Math.random() * 360),
        scaleX: sX,
        scaleY: sY,
        fill: 'yellow',
        stroke: 'black',
        strokeWidth: 1,
        opacity: 0.8,
        draggable: true
    });
}

var layer = new Konva.Layer();

for(var i = 1; i <= 5; ++i){

    var star = crearEstrella();

    layer.add(star);

    crearAnimacion(star);
}

stage.add(layer);