2019, August 12-13: Perseid Meteor Shower Peak Dimmed by Bright Moon


Meteor Shower (NASA Photo)

Annual meteor showers occur when our planet passes through the dusty debris that are spread broadly along a comet’s celestial path.  Each year during mid-August, Earth passes through the track of Comet Swift-Tuttle.  Tiny bits of dusty rock smash into our planet’s atmosphere and are vaporized in a quick streak of light — a meteor or shooting star.  During this time, the meteors can be seen anywhere in the sky, but they seem to emerge from the region of the constellation Perseus in the northeastern sky during the early evening.  As Earth rotates during the night, the point of emergence (radiant) moves higher in the sky.  The best viewing occurs after midnight when the radiant is highest in the sky before morning twilight begins,

It is important to note that the rates that are published in the popular press include dim meteors and those that dazzle our eyes and temporarily leave a streaked glow in the atmosphere.  It is impossible for any one observer to see all the projected meteor counts.  Today many live in cities or larger metropolitan where the glow of bright streetlights wash out the dimmer nighttime stars and dimmer meteors during this shower.

So, for observers in metropolitan areas should half the projected rates (60 meteors per hour).  So we’re down to 30 meteors per hour for most observers in metropolitan areas.  To see the entire sky, the observer needs an all sky camera to catch all the meteors or four friends who look above the cardinal directions while the single observer looks overhead.  So, a lone observer can see 5-6 meteors per hour in a metropolitan area or 10-12 per hour in a dark location. So be patient, especially this year with a bright moon in the sky during the morning.

This year, a gibbous moon adds bright light, so the observable rate is reduced further to perhaps 2-3 in town, 4-6 away from lights.

Here are notes for the mornings of August 11-13 that include some planet observations.  Times are in Central Daylight Time for observers near Chicago Illinois.

  • August 11: The Perseid meteor shower is near its peak. The moon sets a few minutes after 2 a.m. CDT and morning twilight begins about 2 hours later.
  • August 12: Jupiter is now setting before 1 a.m. CDT. For the Perseids, moonset occurs near 3 a.m. CDT and morning twilight begins an hour later. Bright Mercury is 10° up in the east-northeast, 30 minutes before sunrise.
  • August 13: For the peak morning of the Perseids, the moon sets about 15 minutes before morning twilight begins. About 30 minutes before sunrise, Mercury, a little brighter than yesterday morning, is nearly 10° up in the east-northeast.
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