August 10 – 23, 2015
Mt. Washington — Shooting stars are predicted to fly all during the first week of this post, Monday the 10th through Saturday the 15th, at night and especially during the hours before dawn. It is the annual Perseid meteor shower, known for the summer night delight of its meteor-a-minute displays. Another highlight of the year occurs this week: the return to the dawn sky of the brightest star visible from Earth, Sirius the Dog Star. Whereas Perseid meteors will vanish at week’s end, Sirius becomes easier to see close above the horizon in the east-southeast every successive morning. In the evening, Planet Saturn remains a beacon in the southwest from early evening until well after 11 o’clock.
This is an especially good year for the Perseids. Next to good weather, the absence of moonlight and light pollution is key to visibility. With new moon (moon invisible) on the 14th, only a slender crescent appears each morning until then. According to Alan MacRobert, editor of Sky & Telescope, the meteor shower is expected to peak at 4 a.m. on the 13th, favoring Wednesday night the 12th until Thursday first light for camping out under the stars in a dark sky location. In The Farmer’s Almanac, astronomer Bob Berman writes that the peak will be the night of the 11th into the morning of the 12th. In a personal communication, Berman states, “I believe the shower will be almost equally good both nights — 11th-12th should have brighter meteors; 12th-13th should have fewer brilliant ones, but 20 percent more. So, whichever finds good weather!”
A meteor is a streak of light produced by space debris burning up due to friction as it enters Earth’s atmosphere at high speed. In the case of a meteor shower the source of the bright, ephemeral streaks of light is cosmic rock dust strewn by a passing comet years ago. Comet Swift-Tuttle is the source of the Perseids.
The heliacal rising, or first dawn visibility of the brilliant star Sirius occurs this week. Morning stargazing becomes increasingly more attractive now that sunrise is, more or less, 45 minutes later than its earliest rising during most of the month of June. “Heliacal” is defined as relating to or near the sun. Sunrise today, August 10, is 5:55 and Sirius rises at 5:25; sunrise on the 23rd is 6:09 and Sirius rises at 4:34. In our hilly terrain, it might take a few days before the Dog Star becomes visible above your southeastern horizon. There’s a unique charge to seeking out the heliacal rising of Sirius in the mid-summer morning sky since brilliant Sirius is best known as a nighttime winter star.
RESOURCES:
The Perseid meteor shower will be shown on SLOOH.com with real time narration from astronomers on several continents. It will be offered live, and free, using low light video cameras.