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Beyond the blue, beyond the violet, and into the ultraviolet part of the electromagnetic spectrum, the radiant universe appears strangely altered. At these shorter wavelengths and higher photon energies, the hottest stars shine brightly, while the cooler more common stars like the Sun virtually disappear from view. Clusters and associations of young stars are dominated by just a few massive ultraviolet-bright stars, while ancient globular clusters are reduced to their hottest, most rapidly evolving members. Spiral galaxies that look like graceful pinwheels in visible-light images are transformed into knotty webs --- each knot containing thousands of young hot stars. And the space between the stars, clusters, and galaxies appears profoundly black --- up to 100 times darker than the nighttime sky as seen at visible wavelengths.
Until the last decade, our view of the ultraviolet universe was impeded by the stratospheric ozone layer that protects life on Earth from the Sun's harmful UV radiation. Subsequent balloon, sounding rocket, and satellite flights have yielded fascinating glimpses of the ultraviolet universe. In 1990, the Space Shuttle Columbia flew the Spacelab/Astro-1 mission. Astro is the first and only true astronomical observatory to operate onboard the Space Shuttle. It consists of 3 ultraviolet telescopes which are attached to a single pointing system in the Shuttle bay. During the Astro-1 mission, these instruments obtained UV images and spectra of hundreds of astronomical objects. Learning resources relating to this mission include a new slide set and booklet, ``Beyond the Blue: Greatest Hits of the Ultraviolet Imaging Telescope,'' which is being distributed by the ASP through its mail-order catalogue. There is also a teacher's guide with activities, ``Astro-1: Seeing in a New Light'' which is available from the NASA Teacher Resource Laboratories. Sources of information on the upcoming flight of Spacelab/Astro-2 aboard the Endeavour (currently scheduled for February--March 1995) will be discussed.
