Surprising images of dwarf planet Pluto from a flyby of the New Horizons spacecraft put space exploration back in the headlines as one of the biggest science stories of 2015. Instead of a barren, frigid globe, Plato proved to be colorful, contrasty, and complex, with diverse geological structure including mountains, valleys, and plains of water and nitrogen ice, evidence of past and present glacial flows, possible volcanoes spewing water ice from a warmer core, and a thin atmosphere that extends hundreds of miles above the planetary surface. Similar insights are being gleaned from Chiron and the smaller of Pluto's five moons.
2015 also brought Pluto news of a more arcane sort. The historic 24-inch Clark refractor telescope of Lowell Observatory was refurbished and opened to the public for viewing. Why mention Lowell and Earth-based optical astronomy? As a young Lowell employee, Clyde Tombaugh discovered Pluto in 1930 on photographic plates taken with a Lowell instrument. For many, telescopes, whether optical leviathans or the modest backyard variety, are spaceships for the eye and mind that provide a compelling sensory immediacy lacking in the pricier technological tour de force of a spacecraft. Recall the aesthetic impact of the starry night viewed from a dark country path or seeing Saturn for the first time through a telescope. Although modern Earth-based telescopes continue to provide astronomical breakthroughs, old telescopes and the observatories that house them survive as domed, verdigris-covered cathedrals of science. The Pluto flyby of 2015 is an occasion to celebrate space exploration new and old, and the value of looking upward and outward.