Astronomy: Splendor in the Night

After sunset on Oct. 20, a strange and luminous object will rise above the western horizon and make a broad sweep across the darkening sky. Beginning as a fuzzy smear of light, it is expected to grow brighter and brighter until its 20 million-mile tail stretches put to look like a new Milky Way; then its head will appear with a light as great as the full moon. As the newly discovered Ikeya-Seki comet makes its rendezvous with the sun, it will curve high above the northern sky in one of the most...