CANADA: Each year, for a few days around the 21st of October, the Earth interacts with the swarm of meteoroids known as the Orionids. A stream of meteoroids which is actually the scattered bits and pieces left behind by the most famous comet of all, Halley’s comet encircles the solar system.
It is the second such interaction of the Earth this year with the Orionids after we had passed through the stream early in May. When the Earth passes through it in May, the meteoroids come from a different part of the sky and are called Eta Aquarids. These meteoroids are left behind by Halley’s Comet as it flies away from the Sun into the outer bounds of the solar system.
But in October, the Earth crosses Halley’s comet’s inbound path i.e., its path on the way to the Sun. Even though the orbit of the comet is parted by several million miles from the Earth, the dusty residue remains in space long enough to create the Eta Aquarid and Orionid meteor showers in May and October, respectively.
Meteors are commonly referred to as ‘shooting stars’ due to their brief streaky appearance in the night sky. But in reality, these are grains of dust that were suspended in space for years, which get drawn to the Earth by its gravity as we pass close to it.
As the speed of these particles increases up to over 72km per second on their way to the earth’s surface, it generates heat as a result of friction with the atmosphere. This friction releases energy in the form of a short-lived streak of light that we see. A small meteoroid, the size of a pea pod, can form a flash in the sky which can be compared to the brightness of Venus.
Historically, the best time to look for meteors is just before dawn. The chances of catching sight of meteors are higher as they tend to be brighter than the ones visible in the evening due to the light from the Sun reflected by them.
This year is no exception as according to the 2022 edition of Observer’s Handbook of the Royal Astronomical Society of Canada, predawn hours of October 21 is the ideal time to watch for Orionid meteors. The shower will appear from the club of the Orion constellation.