Leonid meteor shower's new moon helps with low cycle

Things like cloudy skies, last summer's wildfire smoke, and full moons all have the potential to put a damper on an early morning meteor-viewing session.

With this year's Leonid meteor shower, at least, you can rule out two of those factors.

The seasonal fires are gone, and the fact that the most recent version of the annual sky show is in a low cycle for meteors per hour is balanced out by this year's new moon, which means there will be no fireball tracers drowned out by a bright lunar source of illumination.

Of course, that still leaves us at the mercy of the overcast-sky gods, but keep your fingers crossed for at least some clear patches in the celestial roof either tonight—early Friday morning (November 17)—or tomorrow (Saturday) after midnight.

The Leonids—so named because they seem to radiate from the constellation of Leo (the lion)—should start becoming visible in the east-northeast at about midnight. With any luck, 10 or 15 meteors with long tails should be visible per hour.

The action heats up, literally, when our planet crosses a swath of debris left by a comet named Tempel-Tuttle. The particles therein, most no bigger than a pea, are already travelling at a pretty high rate of speed. When that combines with the velocity of the Earth as it orbits the sun, the cosmic dust enters our atmosphere and burns up almost instantly at a speed of about 72 kilometres per second.

About three times per century, every 33 years or so, the Leonids are at the high point of their cycle when the Earth crosses their parent comet's debris trail after it has made a new trip around our sun, shedding dust and rocks as it heats up. In those cases, the swarm of meteor sightings can exceed 1,000 per minute!.

Sadly, that is not the case this year (although there are non-peak years where the shower may produce a thousand or so per hour—still pretty spectacular).

So get out around midnight, if the skies cooperate, away from bright sources of illumination like streetlights, and give your eyes 15 or 20 minutes to adjust to the darkness first.

Happy skygazing.