Never mind the Mayans and December 21; you could wake to the heavens exploding as early as this Saturday morning. The Leonids are coming! Originating in debris from Comet Tempel-Tuttle and located near the constellation Leo in the eastern November sky, this meteor shower usually is a bit of a kitten at 10-15 meteors per hour. Honestly that will probably be the case this year. When the cat's fancy changes, however, fireballs roar across the atmosphere like kingdom come.
You may think I'm having my rhetorical way with you. I'm not, though that's tempting. Comets and meteor showers are only semi-predictable. We know when they'll arrive, but their journeys bear enough variables to keep us somewhat in the dark about what they're packing. Meteor showers repeat at the same time every year because the comet debris of which they consist sits on mappable points of our orbit. The paths of their individual particles spread out somewhat due to the geyser effect of the comet's brush with the sun, however, and the tug of other planets can additionally warp these paths.
Comets also have their own elliptical orbits, and Tempel-Tuttle orbits closest to the sun -- or, if you want to be technical and use a lovely word, it reaches perihelion -- about every 33 years. Tempel-Tuttle's perihelion almost exactly intersects earth's own orbit, which means that in a perihelion year the sun is radiating formerly-icy comet dust at almost the same time that this dust hits earth's atmosphere. The result? Massive multi-colored fireballs that you can sometimes hear crackle and boom.
Did you get that? You can hear them! I'm not fabricating, and it gets even better. Sometimes at perihelion, when we pass through the thickest and most volatile part of the meteor stream, the snoozing cat of 10-15 meteors an hour wakes up and attacks. This is called a meteor storm. For an unforgettable hour in 1966, there were thousands of meteors per minute. Per minute! People describe instinctively reaching for an anchor because they felt as if they were rushing into space. I'm faint with envy over such a sight. It wasn't long ago, however, that people were faint with fear.
Meteor astronomy is a relatively new branch of an old science, and in the early part of the nineteenth century people didn't even know that meteor showers were annually predictable. Imagine, then, what it was like to wake up to a cosmic storm. It happened in 1833, and at least one woman died of fright. There are many wonderful accounts of what the sky looked like that night, but this one by John Tabor of Yellville, Arkansas, is my favorite:
Just before midnight, my brother woke up and was nearly paralyzed with fear at beholding the air filled with falling stars. When he was able to speak, he woke us all up and told us to hurry and get on our clothes for the world was coming to an end. I was almost stupefied with wonder and astonishment and hurriedly rose from my couch of bear skins and looked out that the door and saw the whole heavens as far as I could observe, brilliantly illuminated with hundreds and thousands of stars shooting swiftly down toward the earth. Apparently they would disappear or go out before reaching the ground. It was a grand and fearful sight. Like my brother, I and Nimrod Teaf thought it the last of the earth, and we all concluded that it was too late to pray and submitted ourselves to wait for the approach of our destruction . . . The grand display continued and our terror did not grow less. The night seemed a month long, and the end of the world had not come yet. At last, to our surprise, we noticed that day was breaking in the east and it looked as natural as it ever did. As we discerned the approach of day and as it grew lighter, we found that mother earth was still here and the end was not in sight. The flying meteors were gradually obscured by the light of day and we were left unharmed and as far as we knew, the earth remained intact.
All this drama came from particles weighing thousandths of a gram and measuring just a few millimeters across. I may abuse hyperbole sometimes, but when scientists say "particles," they mean particles. We owe the spectacle to the speed of each particle's collision with the atmosphere: upwards of 100,000 miles per hour.
No one can be sure of what you'll see in the hours between midnight and dawn on this Saturday morning, but unfortunately the Leonid perihelion isn't due again 'till 2032. if the Leonids are kittens on Saturday, try the Geminids in the early hours of December 13 and 14. There will be no lunar interference for either shower this year. Unlike the all-or-nothing Leonids, the Geminids consistently offer 50 meteors per hour. They're reliable, just like my beloved August Perseids. Still, wouldn't you love the chance to see that sleeping cat in Leo pounce one of these Novembers?
Whichever shower you watch, take along a thermos of hot chocolate and peppermint schnapps, a warm blanket, a warm someone, and the jazz standard "Stars Fell on Alabama." It was written about the Leonid Storm of 1833, and it includes the line "we kissed in a field of white." You know what to do. Just don't close your eyes.
Definitions verified and cross-referenced via NASA, EarthSky.com, Sky and Telescope, and Wikipedia. John Tabor account from Kwas, Mary L. "The Spectacular 1833 Leonid Meteor Storm: The View from Arkansas. The Arkansas Historical Quarterly. 58:3, Autumn 1999. 314-324.