During the past few weeks, you might have noticed a few meteors, or “shooting stars”, at night. You were witnessing one of the best meteor showers of the year.
The Perseid meteor shower, which this year started on July 14, is now underway and will conclude on August 14.
The best time to see the most meteors will be on the night of August 12 and into the morning hours of the next day, August 13. This year, the crescent moon sets at about 10:40 p.m. (Pacific time), leaving us with a dark sky. By contrast, next year’s Perseids takes place under a full moon, which will drastically reduce the hourly rate of visible meteors.
If you have the chance to observe from dark skies absent of any competing lights, you can also enjoy the visible band of our Milky Way galaxy as this collective glow of billions of distant stars stretches from Sagittarius in the south to Cassiopeia in the northeast.
Also, brilliant planets Jupiter and Saturn (to Jupiter’s right) will be out all night long to keep you company. They are unmistakable and located to the left of Sagittarius.
The peak of the Perseids produces about 90 meteors per hour but occurs durimg the late afternoon, in daylight, on the 12. Toward the end of the night, when the constellation Perseus is high in the sky (about 3 a.m.), we should still see from 50 to 60 meteors per hour striking the atmosphere at 59 kilometres per second (36 miles per second), about one per minute.
A higher number of bright fireballs may be seen on nights before the peak rather than nights after. The friction of comet debris causes the “flash” or “streak”, which safely vaporizes about 80 kilometres high in the atmosphere, with little chance of meteorites hitting the ground.
The Perseids' parent comet is named Swift-Tuttle, a 26-kilometre (16 mile-) -wide mountain of ice, dust, and gravel that last appeared in 1992 in its 133-year orbit around the sun. It will return in the year 2125, replenishing a fresh path of comet debris ejected from the its surface as it gets close to the sun, our star.
That is where the solar radiation interacts with the comet, causing volatile material to vaporize and create the comet’s coma, or cometary fog, measuring almost 100,000 kilometres in width around its much smaller nucleus. A dust tail forms as debris is blown off the comet’s surface, much like confetti blowing off the back of a truck on the highway.
As Swift-Tuttle retreated from the sun’s warming effects and back to the outer solar system, it faded away becoming a dark mountain once again, only to be awakened by the sun again upon its return.
The new comet dust lingers in space until Earth plows through the debris field in its yearly orbit around the sun, much like a runner crossing the finish line of a race. This is how the Perseids and other meteor showers are known to occur at the same time each year.
So gather a few friends and/or family members, set up chairs, bring snacks, and take advantage of warm moonless conditions to view this epic display. Look up at the stars, listen to the crickets and frogs, and let nature bring a sense of calm over you.
Till next time, clear skies.