They return year after year, and for many of us, they spell holidays and warm summer nights. But who — or what — are they? The Perseid meteors, of course!
Each year around mid-August, Earth passes close to the orbit of periodic comet 109P/Swift-Tuttle, whose wake is peppered with billions of dust particles that give rise to the famous Perseid meteor shower. However, the quality of the celestial show varies dramatically from year to year, mainly as a function of Earth’s distance from the densest parts of the particle stream, but also as a function of the Moon’s presence.
The Perseids in 2018
Great news! From an astronomical point of view, the Perseids will take place under excellent circumstances in 2018, and observers across North America could be in a favourable position to benefit from the situation.
First of all, peak activity for the Perseids is expected between 4:00 p.m. on August 12 and 4:00 a.m. on August 13 (all times Eastern Daylight), with greatest probability around 10 p.m. on the 12th; so it has a good chance of happening during night-time in Quebec.
The first meteors could appear as soon as the sky darkens, but it’s after midnight that the show will really take off. The radiant, the area in the sky from where the meteors appear to emanate, climbs higher in the sky during the second half of the night: it will reach optimum height just before dawn. In Quebec, this corresponds to the timeframe when the shower should be within a few hours of its maximum intensity.
Another important factor is that the Moon will be new on August 11 and will not affect observations in any way. This means it will be worth the effort to travel away from light pollution and find the darkest, clearest observing site possible, in order to take full advantage of these perfect conditions. Under a moderately dark sky, about 30 meteors should be visible per hour, and more than 60 or even 70 at a site completely free from light pollution.
Should the weather be uncooperative during the night of August 12 to 13, keep in mind that the Perseids are also visible a few nights before and after the period of peak activity — but one has to expect significantly fewer meteors. In fact, you can spot Perseids as early as mid-July, and the shower remains active through the third week of August.
Let’s hope for clear skies… and get your wish lists ready!