Thursday, January 19, 2012

Comets

In the deep winter of 1744, Sophia, a fourteen-year-old minor German princess, was on her way to Russia. She had been summoned, with her mother, by the Empress Elizabeth, as a potential bride for the fifteen-year-old heir to the Russian throne. Somewhere along the way, about halfway between Berlin and St. Petersburg, she viewed the Great Comet of 1744 (now designated C/1743X1). "I had never seen anything so grand," she later wrote in her memoirs. "It seemed very close to earth."

Lovely, spunky young Sophia later became Catherine the Great, empress of all the Russias, and I glean the fact of her observation of the comet from Robert Massie's new best-selling biography. The comet she watched was the sixth brightest in recorded history, and the brightest of her century. It reached an apparent magnitude of -7, as bright as a crescent Moon. In early March, it dazzled in the morning dawn, six tails reaching up from the horizon like a Japanese fan.


Two centuries earlier, or even a century, such an apparition might have been considered a portent or sign from God. By 1744, every educated person in Europe -- and Sophia was well educated -- knew that comets were natural celestial events. In 1705, Newton's friend Edmund Halley had applied Newton's physics to these occasional visitors, and shown that many comets are periodic, including the comet that bears his name. He predicted its return in 1758, but did not live to see it, dying in 1742 -- also just missing the comet that so thrilled Sophia.

And my lifetime? The brightest comet so far was Ikeya-Seki in 1965. I have lovely memories of Comet West in 1976, and Comet Hyakutake in 1996, both of which I have written about in one place or another. But perhaps the biggest thrill was a comet that wasn't nearly so bright (this time around), Comet Halley in 1984, for which Sky & Telescope magazine sent me off to Australia to record what I saw. What a privilege to be in the shadow of Ayers Rock with several dozen other people so bedazzled by comets that they would travel half-way around the world to peek at a fuzzy spot in a dark, dark sky.