¡SkyCaramba! Weekly astronomy blog for the week ending August 10, 2013
About 11 nights into August, the Perseid meteor shower peaks. You may have already seen some. And you may see them for a few more weeks. The meteors appear to radiate from a point in the constellation Perseus. That’s a far northern constellation, so you may not see many meteors if you’re in the southern hemisphere.
A thin crescent moon in the evening won’t interfere with the Perseids much this year. It will be set by late evening when shower activity is more likely to pick up. You can also continue watching after midnight until dawn. You could see 60 or more per hour.
Seeing the Perseids is the best you can come to seeing Comet 109P/Swift-Tuttle for about another century. Perseid meteors come from dust left behind in the comet’s orbit. That orbit takes 133 years. It last came our way in 1992. While the comet won’t come close to us again for quite some time, Earth passes through its dust trail at the same time every year.
It’s only in the last two centuries that astronomers understood meteor showers were yearly events. From year to year, sometimes our planet passes near a dust trail or through a thin part of one. And moonlight keeps us from seeing dimmer meteors in some years. The Perseids have been known to be an annual occurrence since 1835.
The Perseids are sometimes called the Tears of St. Lawrence. At the beginning of August 258, a Roman emperor had ordered that all of the Catholic Church’s deacons, priests, bishops, and the pope be killed. The authorities caught up with the deacon Lawrence on the 10th. Because the date is close to when the Perseids peak, these meteors have been associated with the St. Lawrence feast day.
If you see any meteors during August, see if their trails point back to Perseus. If so, those are probably Perseids. ¡SkyCaramba!