Maps from Google Earth, a desktop application, can now be viewed online through a new browser plug-in.

In addition, Web site owners can now embed Google Earth 3-D views into Web pages.

“Driven by an extensive JavaScript API, you can control the camera; create lines, markers, and polygons; import 3-D models from the Web and overlay them anywhere on the planet,” said Google (NSDQ: GOOG) engineer Paul Rademacher in a blog post. “In fact, you can even overlay your content over different planets, stars, and galaxies by toggling Sky mode, letting you build 3-D Google Sky mashups. You can also enable 3-D buildings with a single line of JavaScript, attach JavaScript callbacks to mouse events, fetch KML data from the Web, and more.” KML is a file format for displaying geographic data in a browser.

Rademacher says Google’s goal is to open up the core of Google Earth to developers so they can create the next great 3-D geo application.

Web sites using the Google Maps API can now enable those maps to be viewed through Google Earth’s 3-D view. All that’s required is a single line of JavaScript code.