If you’re living on the East Coast and it’s clear this Sunday evening, Nov. 19, step outside around 11:45 p.m. and take a few moments to scan the sky for the Leonid meteor shower.

Astronomers are predicting a slightly better show this year, as we pass through the dusty trail of comet 55P/Tempel-Tuttle.

Bright streaks of light will stream across the sky from east to west as the Earth plows through bits of dirt, about the size of beach sand, that were left behind by the comet. The Leonids are an annual event, but this year the show may have a little extra burst just before midnight, as we pass through a thick filament of dust that was blown off the comet in 1932.

Meteor showers are a form of cosmic pollution left behind as comets spew out dust particles, like dust kicked up behind a speeding car on a dry dirt road. Those beautiful tails that give comets their ghostly appearance are plumes of dust, gas and ice that have been blown off the surface of the comet by radiation from the sun. The dust trail, millions of kilometres long, remains spread around the comet’s orbit, which in the case of Tempel-Tuttle, happens to cross the orbit of the Earth. Every November, the Earth plows through the dust trail, and the particles hit our planetary windshield, our atmosphere, where they are vaporized by air friction.

The last time we passed through this filament in the trail was 1969, when activity suddenly increased for about an hour. This year, sky watchers are predicting a fairly good show of a meteor every 30 seconds or so, for that hour.

If you do spot a meteor, think about this: the speed of those streaks across the sky is as much a product of our own speed through space as theirs. We tend to forget that the Earth moves 30 kilometres per second in its orbit around the sun. The meteors are one of the few opportunities we have to see how fast our spaceship Earth actually moves as we journey through the cosmos.

For more information on meteors: http://www.amsmeteors.org/.

— Bob McDonald