on 'zoom' event

[kingio]

I've checked http://www.webglearth.org/ and it talks about on(type:string, function(event)) : number?, that "Registers function to be called when certain event occurs", but doesn't list which events can you listen I've tried mousewheel and zoom but it doesn't get triggered.

¿Is there any way to detect zoom changes?

[kingio]

this.earth.on("wheel", function (event) {
                console.log(event);
            });