08/03/2015 – Ephemeris – The Perseids are coming!

Ephemeris for Monday, August 3rd.  The Sun rises at 6:30.  It’ll be up for 14 hours and 35 minutes, setting at 9:06.   The Moon, half way from full to last quarter, will rise at 10:58 this evening.

After the Moon sets in the evening and morning hours for the next week and a half the numbers of meteors visible will increase each night.  These are members of the Perseid meteor shower of August.  The peak this year is expected to be during the 2 o’clock hour on the morning of the 13th.  These meteors are the result of debris left in the orbit of Comet Swift-Tuttle shed by innumerable visits to the inner solar system.  Every year at this time the Earth passes through this trail of debris which intersects its orbit giving rise to the meteor shower.  We call them the Perseids, because the appear to come from the direction of the constellation Perseus the hero, which is first seen in the early evening low in the northeast.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Perseid radiant at 10:30 p.m.

Orbit of Comet 109P/Swift-Tuttle. Blue line is the comet’s orbit, coming from above (North). Credit NASA / JPL / Applet by Osamu Ajiki (AstroArts), and further modified by Ron Baalke (JPL)

The distances in the lower left corner are the comet’s current distances from the Earth and Sun.  AU is astronomical units the mean distance between the Earth and Sun.  The comet’s last pass through the inner solar system was in 1992.  Swift-Tuttle is now out just past the current position of the dwarf planet Pluto.  Link to the animation from which the above image was taken and other information on Comet Swift-Tuttle go to http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=109P;cad=1