Physics Today: Opportunities for amateur astronomers to observe the night sky are becoming rare as light pollution fades the night sky away. Yet, thanks to a new product called Google Sky, a simple desktop computer can provide some unprecedented views of the universe that were previously available only to professional astronomers. Google Sky is based on the same technology as Google Earth and displays the visible universe based on a mosaic of images from the Sloan Digital Sky Survey, the Digitized Sky Survey and the Hubble Space Telescope.

Thumbnail images at the bottom of Google Sky's display can bring up high resolution images of the planets, the constellations, highlights from the Hubble Space Telescope, famous stars, galaxies and nebulae, and views of the universe in the x-ray, ultraviolet and infrared. Other items available through Google Sky include:

* Infrared - An infrared view of the sky from the Infrared Astronomical Satellite (IRAS). Change the transparency of this layer by moving the slide bar to blend the optical and infrared.
* Microwave - A view of the microwave sky from NASA's Wilkinson Microwave Anisotropy Probe (WMAP), which shows the universe as it was 380,000 years after the big bang.
* Historical - The sky as drawn by Giovanni Maria Cassini (printed in 1792) showing the constellations in their classical form from the collections of David Rumsey.

Other online observatories
Bradford Robotic Telescope
Micro-Observatory
Seeing in the Dark
Slooh