The Unpredictable Leonids

Wow – a meteor shower with an average rate of just 15 “shooting stars” an hour at its peak but one that has on occasion suddenly exploded at a rate of 40 per second!  That’s the famed annual Leonid’s, which occur this year on the night of November 16th into the morning of the 17th.  No other shower in recorded history has produced such an intense burst of activity—nor been so erratic and unpredictable.

This year’s Leonid display happens under good conditions as far as interference from moonlight is concerned, occurring with a crescent Moon that sets early in the evening leaving behind a dark sky.  The meteors will appear to radiate from the head of the constellation Leo, which looks like a backwards question mark and is known as the “Sickle Asterism.”  Setting your Scientifics Star and Planet Locator for the 16th at whatever time you plan to venture out, you will see that the constellation itself doesn’t clear the northeastern horizon until after midnight on the night of the shower.  However, meteors can still be seen throughout the evening streaming up from below the horizon.

Normal rates can range from as low as a disappointing 10 to 15 meteors per hour to as high as what happened in November of 1966 (and at other times in previous years — especially 1833 and 1866, when the sky was so full of meteors that people thought the world was coming to an end!).  As dawn approached here on the East Coast, I saw a seeming blizzard of celestial “snowflakes” in the brightening sky!  Further west under still dark skies (such as at the Kitt Peak National Observatory in Arizona), rates of 40 to 50 meteors per second were seen (and also photographed using all-sky cameras), with some estimates placing the actual number at an astounding quarter million shooting stars per hour!

The actual Leonid storms themselves appear to come in 33 year intervals, with typically very low activity in the periods between.  However, there have been surprising short-lived bursts, as in 2001 when several hundred meteors per hour were seen for a few hours—so you really never know what to expect.   Then what about this year?  Peak activity of at least 100 or more Leonids could happen on the very early morning of November 17th, according predictions from various sources.  But other meteor experts aren’t so sure.  So if it’s clear on the evening of the 16th, check the sky before retiring and if no unusual activity is seen after being in the dark for, say, 15 minutes (giving your eyes time to dark-adapt),  set your alarm and check again perhaps around 3:00 a.m.   Whatever you do, be sure not to miss at least checking out this year’s Leonid display—just in case the “Lion Roars” again!


— James Mullaney

Former assistant editor at Sky & Telescope magazine & author of 10 books on stargazing. His latest, Celebrating the Universe!, is available from