Bob Moler's Ephemeris Blog

Ephemeris for Monday, August 12th. The sun rises at 6:41. It’ll be up for 14 hours and 10 minutes, setting at 8:52. The moon, 2 days before first quarter, will set at 11:26 this evening.

The Perseid meteor shower is still active. Their peak will be this afternoon. So starting at moon set at 11:26 or so it will be dark enough to see them. Meteor showers are caused when the earth crosses the path of a periodic comet and runs into the debris liberated by the comet’s past visits near the sun. Comet Swift-Tuttle is the comet responsible for the Perseids. It has an orbit of the sun of 130 years. Every time the comet comes close to the sun, it liberates a cloud of small gravel that’s too massive to be swept into the comet’s tail, however it is affected by the pressure of sunlight. These make the prediction of the time of the meteor shower interesting, or that a particular cloud may miss the earth this time to hit it some other passage.

Addendum

My best Perseid photo. From the 70’s.