gistfile1.txt

            $("#sun").draggable({
            axis: "x",
            drag: function() {
                var xpos = parseFloat(this.style.left, 10) - 100;
                var ypos = Math.sqrt(300 * 300 - xpos * xpos) * 0.75;
                this.style["margin-top"] = (-ypos) + "px";
            }
        });

var width = 300;
var rise = width / 2;

$("#sun").draggable({
axis: "x",
drag: function() {
var x = this.offsetLeft + (width / 2);
var y = this.offsetRight + (width / 2);

    var heightPct = 1 - ((x ^ 2) / (x + y)^2);
    this.style["margin-top"] = (heightPct * 30) + "px";
}

});