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The night the stars fell
On the night of 12 to 13 November 1833 the sky over North America rained meteors, with estimates of tens of thousands an hour. Many people thought the world was ending. The event helped found the modern study of meteors, because observers noticed that all the streaks seemed to radiate from one place in Leo.
A second great storm came in 1966, with rates in the tens of thousands an hour for a short time over the western United States.
A 33-year heartbeat
The parent comet, Tempel–Tuttle, returns to the inner Solar System every 33 years, and each pass lays down a fresh, dense ribbon of dust. When Earth crosses it soon after the comet passes, a storm can happen. Strong displays ran from 1999 to 2002, with rates reaching thousands an hour in some places.
Between those years the dust has spread out, and the shower falls back to a modest level. Forecasters model each trail, so you can look up any upcoming good year before planning travel.
Going back through historical records, the Yale mathematician Hubert Newton worked out the 33-year rhythm and predicted that a storm would return in 1866. It did, and the success showed that meteor showers could be forecast like eclipses.
The Leonids on an ordinary year
In a normal year, expect about 10 to 15 meteors an hour from a dark site, after midnight when the head of the Lion rises. The meteors are fast, at about 71 km per second, among the fastest of any shower, and often bright and tinted green or blue. Fireballs are not unusual, and some leave trains that linger for several seconds.
Watching in November
- Wait until the radiant is up. Leo rises around midnight, so aim for the small hours.
- Dress for frost. Mid-November is already cold in the north.
- Check the Moon. Moonlight swamps the faint meteors that make up most of a normal Leonid year.
Where to go next
A few weeks later the year's richest shower, the Geminids, arrives. The full list lives on the meteor showers hub.
Questions people ask
Is a Leonid storm coming?
Storms are tied to the comet's 33-year cycle and are predicted by specialists. In an ordinary year, expect a modest shower.
Why is it called the Leonids?
The meteors seem to come from the constellation Leo, the Lion.
How fast are Leonids?
About 71 km per second, among the fastest of any shower.