06/02/2015 – Ephemeris – Bright clouds that appear near the end of twilight

Ephemeris for Tuesday, June 2nd.  Today the Sun will be up for 15 hours and 21 minutes, setting at 9:21.   The Moon, at full today, will rise at 9:18 this evening and tomorrow the Sun will rise at 5:59.

This time of year one can see, on rare occasions, some ghostly clouds called noctilucent clouds.  Noctilucent means night shining.  These are silvery clouds that can be seen near the end of twilight.  We’re a bit south of the prime latitudes to see them from 50 to 70 degrees both north and south of the equator.  I’ve seen them but a few times.  They move rather rapidly, even though they’re at an altitude of around 50 miles.  The clouds appear to be made of ice crystals that possibly form around meteoritic dust. Their appearance cannot be predicted, but be aware that they may appear near the end of twilight and they are white, move rapidly, and are not the twilit clouds lower down.  These clouds are most numerous during July and August.  They seem to be showing up early this year.

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

Addendum

Noctilucent clouds, Kuresoo bog, Soomaa National Park, Estonia. July 26, 2009 by Martin Koitmäe. From Wikimedia Commons.

NASA Aeronomy of Ice in the Mesosphere (AIM) satellite data of Earth’s north polar region from July 6, 2014. Credit LASP/University of Colorado.