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    Cernan Earth and Space Center


    Grade Level: 5th grade and up
    Length: 40 minutes

    Galaxies is a multimedia program that combines stars, video, panoramic scenes, planetarium special effects and numerous astronomical photographs taken at some of the world's largest observatories to visually describe the largest building blocks of the universe -- galaxies. Galaxies are gigantic collections of billions of stars, yet most are so distant that the light we see from them has travelled millions of years to reach us. This planetarium program, written by noted author and scientist Timothy Ferris, examines the wonders of our own Milky Way galaxy, including star clusters and nebulae, and then focuses on the more distant and mysterious galaxies that comprise the universe.

    Galaxies begins and ends with an updated version of a scene from Thornton Wilder's play Our Town where the lead character Rebecca recites her Grover's Corners address in cosmological terms. Today, with a greater understanding of the structure of the universe, we would recite this cosmic address a bit differently.

    The program next describes the different classifications of galaxies, including spiral, elliptical, S0, irregular and peculiar, and how our own Milky Way galaxy is different and similar to these types. Using the planetarium's star projector, viewers are taken on a visual tour of the Milky Way, describing such notable features as the Great Rift near the constellation Cygnus, the Southern Cross and the Coal Sack, the center of the galaxy in Sagittarius, the Crab Nebula and the supernova that created it, and how the Milky Way would appear if our eyes were sensitive to gamma rays, x-rays, infrared or radio waves.

    Star clusters are next described. The "open" star clusters, such as the Pleiades in Taurus, are found scattered throughout the disk of the Milky Way, while the "globular" clusters, which may contain 100,000 stars or more, form a spherical halo that surrounds the galaxy.

    Viewers then journey to the Milky Way's two companion galaxies, the Large and Small Magellanic Clouds, and the Andromeda Galaxy. Several unusual galaxies are next highlighted, including one galaxy (Centaurus A) that may be cannibalizing a smaller, nearby galaxy and other pairs of galaxies that are colliding with one another. Superclusters of galaxies, the largest organized structures in the universe, are briefly described.

    The final segment of the program describes "lookback time," which is how some astronomers describe the fact that we are looking back in time whenever we observe the sky. Whether it is a nearby star or a distant galaxy, the light we see when we observe the universe has travelled hundreds, thousands or millions of years before reaching our eyes. A brief question-and-answer period follows the presentation of Galaxies.