Archive for June 25, 2019

06/25/2019 – Ephemeris – Weird clouds of the twilight zone

June 25, 2019 Comments off

Ephemeris for Tuesday, June 25th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, at last quarter today, will rise at 2:23 tomorrow morning.

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 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 meteoric dust. Their appearance cannot be predicted, but show up near the end of twilight and they are white, and are not the usual reddish clouds of twilight. These clouds mostly appear in July and August. But I’ve seen many recent reports of them from Europe.

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


Noctilucent Clouds

Noctilucent clouds, Kuresoo bog, Soomaa National Park, Estonia. July 26, 2009 by Martin Koitmäe. From Wikimedia Commons. is a great place to learn more and hosts a gallery of recent noctilucent cloud photos.