Autumn's here—Happy New Year! Not for me, that pallid substitute in January with its noisemakers and forgotten resolutions. My calendar resets annually with the opening of classroom doors, no matte ... [+]
The last apparition of Halley's Comet was in 1986, approaching Earth as close as 0.4 astronomical units. Halley takes a long journey to visit us. The comet follows an elliptical orbit that reaches past Pluto before returning to the inner solar system. Its next flyby will be 76 years later, in 2061. During its orbit, Halley leaves fragments of itself in its trail—stray rocks, dust, and sometimes ice, blown away by the solar winds, floating in clumps across space. Occasionally, the Earth passes through this debris, causing it to rocket toward the planet at high speeds, burning brightly as it di