Home > Constellations, Ephemeris Program, Mythology, Nova, Observing > Ephemeris: 05/20/2025 – Corona Borealis, Ariadne’s Crown

Ephemeris: 05/20/2025 – Corona Borealis, Ariadne’s Crown

May 20, 2025

This is Ephemeris for Tuesday, May 20th. Today the Sun will be up for 15 hours and 1 minute, setting at 9:10, and it will rise tomorrow at 6:08. The Moon, at last quarter today, will rise at 3:12 tomorrow morning.

There are two bright stars in the eastern part of the sky. High in the southeast at 11 PM is Arcturus, and in the east northeast, lower down is the star Vega. A third of the way between Arcturus and Vega is a small arc of stars called Corona Borealis, the northern crown. It is a small constellation. The brightest star in it is called Alphecca. According to Greek mythology it is the crown given to Princess Ariadne, daughter of King Minos of Crete. Of interest in the next year or so is a possibility of a nova or bright star appearing just south of that arc of stars for about a week. It is a recurrent nova, which explodes about every 80 years. The last time was in 1946, so the next time would be within the next year or so. And astronomers are breathlessly waiting for that to happen.

The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.

Addendum

Looking in the east southeastern sky for Corona Borealis. The view is from the horizon to just pass the zenith. Corona Borealis is about 1/3 of the way from Arcturus which is high in the southeast to Vega lower in the east-northeast.. It’s a small semicircle of stars. Created using Stellarium, LibreOffice Draw, and GIMP.
T Coronae Borealis (T CrB) nova finder.
T Coronae Borealis (T CrB) nova finder, when it occurs. This is the orientation of its position in the sky if it occurs in the spring. Created using Stellarium, LibreOffice Draw, and GIMP.
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