Since its launch on July 23, 1999, the Chandra X-ray Observatory has been NASA's flagship mission for X-ray astronomy, taking its place in the fleet of "Great Observatories."

As Chandra celebrates its fifth year of observations, you are invited to experience the impact Chandra has made on astronomy and physics. From Chandra's "First Light" to its fifth anniversary, explore the wonders of the X-ray universe through this special edition section of chandra.harvard.edu. Activities include voting for your favorite Chandra image, figuring out 20 Chandra images, viewing highlights from the past 5 years and more.

For more information, images, and materials visit the official Chandra website at http://chandra.harvard.edu.