The Perseids and The Gibbous Moon

The Perseid Meteor Shower 2016 at Frosty Drew Observatory.

The Perseid Meteor Shower 2016 at Frosty Drew Observatory.

Remember that amazing meteor shower that happens in August? That is the Perseid Meteor Shower and it started on July 17th, making now the time to plan where you will be for the August 12-13th shower peak. Meteor activity will continue to increase as we close in on the peak dates with bright meteors becoming very frequent overnight. Sadly, the bright 80% waning gibbous Moon will obscure many of this year’s falling stars, though not all of them. Bright meteors will blaze through the moonlight making for excellent views. All we need now is clear skies, late night stamina, and loads of enthusiasm to make for a stunning night of shooting stars.

The Perseid shower is the result of Earth passing through a debris field left behind by comet 109P/Swift-Tuttle. Discovered in 1862 by Lewis Swift and Horace Tuttle, comet 109P was identified as the source of the Perseid shower in 1865. The comet has a 133 year orbit around the Sun and made its last visit to the inner solar system in 1992.

Meteor showers are named after the constellation that their meteors appear to radiate from. This is called the "radiant point". The Perseid shower radiates from the constellation Perseus, visibly about half way between the constellations Perseus and Cassiopeia near the naked eye visible Perseus Double Cluster. Since Perseus will rise around sunset, the radiant point will be about 37º above the horizon at 1:00 a.m. on Saturday, August 12th and rising higher over the course of the night, eventually passing overhead. This places the radiant point at an excellent place for viewing.

This year we have to share our amazement with the bright gibbous Moon, which will rise on Friday, August 11th at 10:15 p.m. shining at near 85% full and a little later on Saturday at 10:47 p.m. blasting 76% full. This will place Saturday morning and Sunday morning, which are the best times to view, under the bright Moon that will out shine all but the brightest meteors. Though you can fight back! Setting up with the Moon out of your view will allow you to spot a few more meteors. You can accomplish this by facing the northern sky or placing the Moon behind a terrestrial object like a tree or building.

Viewing the Perseid show is a cake walk. Grab a reclining lawn chair or a blanket and lay on your back looking towards the zenith (top of the sky). Since the Perseid radiant point is the top of the constellation Perseus, which will rise overhead from the northeast, orientate your body so your feet are towards the northeast. Meteors will be frequent and appear to originate from the radiant point. Note that you will want to setup in a way where the Moon is out of your sight, even if that means facing north instead of northeast.

Frosty Drew Observatory will open all night on Friday, August 11th and Saturday August 12th for the Perseid peak. Starting at sunset, we will offer views of Saturn's rings, Jupiter’s moons, and more. Once meteor activity begins to increase, we will close the Observatory telescopes and make our way to the Observatory court yard where the Perseid shower will be taking off. We will stay on site until the pre-dawn Sun kicks us out, weather permitting. If weather is favorable, we will likely be on site overnight Saturday as well. Unfortunately, the Milky Way will only be visible for a short period after twilight wanes until the Moon rises. So stop in during the Perseid Meteor Shower peak and enjoy a fantastic night out under a sky with shooting stars blazing by.


Scott MacNeill
Scott MacNeill
Entry Date:
Aug 9, 2017
Published Under:
Scott MacNeill's Columns
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