Bob Moler's Ephemeris Blog

This is Ephemeris for Friday, August 12th. Today the Sun will be up for 14 hours and 11 minutes, setting at 8:53, and it will rise tomorrow at 6:42. The Moon, 1 day past full, will rise at 9:48 this evening.

The Perseid meteor shower will reach its peak tonight as the nearly full Moon rises. Only the brightest of these meteors will be visible in the bright moonlit sky. Next year the Moon will be less bright and will only interfere in the early morning hours. Comet Swift-Tuttle is responsible for shedding the tiny bits of rock that end up orbiting the Sun near its path. The Earth plows through these particles every year at this time, giving us a great sky show, which at peak on a dark morning provide 60 or more of these so-called shooting stars per hour. The members of the Perseids will all seem to come from the northeastern sky, from the top of the constellation of Perseus the hero. The star figure to me instead looks like the cartoon roadrunner running up the sky.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.

Addendum

Perseid fireballs in one of NASA’s all sky cameras during the morning hours of August 13, 2017. This is a long time exposure. The bright swath in the image is the Moon that morning. Since it is a time exposure, the radiant is also moving with the earth’s rotation, so the meteors only seem to come from the northeastern sky. North is at the top, and East is to the left. The Moon that morning was 1 day before last quarter, so tonight’s Moon will be even brighter. Credit NASA.

Screen capture of an interactive animation of the orbits of the Perseid meteoroids and the inner planets. The planets move counterclockwise, while the meteoroids move clockwise and cross the Earth’s orbital plane at a high angle. Image taken from the International Meteor Organization, imo.net. Interactive animation by MeteorShowers.org.