Free The Pluto Files: The Rise and Fall of America's Favorite Planet by Neil deGrasse Tyson Page B

scientifically sensible—a kind of intellectual high road that sidesteps nomenclature altogether.
     
    The Rose Center for Earth and Space also contains a 400-foot, square walkway that we call the Scales of the Universe. Not to be confused with the famous exhibit on how much you would weigh while standing on various cosmic objects, the Scales of the Universe consists of multiple vistas along a path that surrounds the giant Hayden Sphere. The sphere houses not only the Space Theater but also, in its belly, a walk-through Big Bang experience—a separate venue where we re-create the first few moments of the universe. We further exploit the outside of the sphere as an exhibit element, allowing us to compare things of greatly varied size. With models mounted on the railing of the walkway and suspended from the ceiling, the exhibit shifts by a power of ten in scale for every few yards you walk. At the beginning, the sphere represents the entire universe, and the model on the railing represents the Local Supercluster of galaxies. Take a few steps, and the sphere now represents the extent of the Local Supercluster, while the next model you encounter represents the Milky Way galaxy. Take a few more steps, and the sphere represents the Milky Way, and the model on the railing represents a star cluster. Keep walking, and the scale of comparison keeps dropping and dropping and dropping until you enter the nucleus of the hydrogen atom.
    About halfway along this walkway, you reach a vista where the sphere represents the Sun, while models on the railing represent the terrestrial planets, ranging from the size of your fist for Mercury to the size of a cantaloupe for Venus and Earth—all in correct relative size to each other. Suspended near the Sun are scale models of the Jovian, gas giant planets, which are much too large and glorious to mount on the railing.
    It’s an exhibit on the relative sizes of things. In this picture-perfect spot the visitor is comparing the size of the Sun with that of the terrestrials and the Jovians in one glance. We had no compulsion to include Pluto. Why? We don’t show comets. We don’t show asteroids. We don’t show the seven moons in the solar system that are bigger than Pluto. We were making a simple comparison of how two families of objects in the solar system contrast with the Sun in size.

    Figure 4.6. Models representing the terrestrial planets, seen from the Scales of the Universe walkway in the Rose Center for Earth and Space. With the Sun represented by the Hayden Sphere (see Figure 4.5), models of the terrestrial planets, in correct relative size, are mounted on the railing. On this scale, Mercury (left) is a little larger than a baseball; Earth and Venus, soccer balls; and Mars (right), a bocci ball. Pluto, not being a terrestrial planet, does not appear among them. (Earth serves as the principal size referent to the Sun and so remains unpainted, along with other fiducial models of the exhibit.)

    Figure 4.7. View from the Scales of the Universe inside the Rose Center for Earth and Space. The Hayden Sphere, representing the Sun from this vista, is juxtaposed with the gas giant (Jovian) planets Jupiter, Saturn, Uranus, and Neptune, each suspended from the ceiling. Pluto, not being a Jovian planet, does not appear among them. For any given scale, all models are constructed and displayed in correct relative size to each other.
    If you want to learn about the form and structure and contents of the solar system, then visit the Planet Zone in the Hall of the Universe. That’s where you will find Pluto, in a transparency, by the way, huddled with its fellow members of the Kuiper belt.
     
    The new Rose Center for Earth and Space opened to the public on Saturday morning, February 19, 2000. We were not unmindful of the potential for controversy over how we had organized the planet exhibits. But at no time during the hundreds of radio, print, and television interviews I gave—for domestic as well as