Home > Double star, Ephemeris Program, Observing > Ephemeris: 06/17/2025 – Finding the naked-eye double star Mizar and Alcor

Ephemeris: 06/17/2025 – Finding the naked-eye double star Mizar and Alcor

June 17, 2025

This is Ephemeris for Tuesday, June 17th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:56. The Moon, 1 day before last quarter, will rise at 1:36 tomorrow morning.

In tonight’s sky, the Big Dipper is high in the northwest hanging from its handle. In its handle is a star or two that are fascinating. It’s the star at the bend in the handle. It’s called Mizar. Next to it, for those with good eyesight, is a dimmer star, called Alcor. The name Mizar is from the Arabic, meaning apron or cover, while Alcor means the forgotten one. In ancient times the ability to actually see both stars was a test for good eyesight, especially for Arabic warriors. The pair is also known as the “Horse and the Rider”. Some Native American tribes saw the handle stars as hunters tracking the Great Bear, Ursa Major, of which the Big Dipper is a part, rather than its very unnatural tail. Dim Alcor became a hunting dog.

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

This is the Big Dipper at about 11 PM June 17th, high in the northwestern sky, showing the location of Mizar at the bend of the handle with its companion Alcor. Created using Stellarium, annotations with LibreOffice Draw, and GIMP.
A telescopic view of Mizar in Alcor
Here is a telescopic view of Mizar in Alcor. Note that Mizar is again a binary star. Its components A and B, A being the brighter of the two. Binoculars can’t quite split Mizar but it can be done with a small telescope. The dim star between the two is a background star about 300 light years away compared to Mizar and Alcor’s 81 light year distance. Created using Stellarium, annotations with LibreOffice Draw, and GIMP.

Categories: Double star, Ephemeris Program, Observing Tags: ,