Today’s Astronomical Events – April 23rd, 2015

Messier 101, aka the Pinwheel Galaxy, is at its best visibility for the year tonight. A beautiful face-on spiral galaxy located close to Mizar in the constellation Ursa Major, the Great Bear, it was discovered by Pierre Méchain in 1781 and lies some 21 million light years away.

At magnitude 7.9, it’s one of the brightest galaxies and may be glimpsed in binoculars, but like many deep sky objects you’ll need clear, dark skies to see it.

(Click on an image to enlarge.)

Map courtesy of Mobile Observatory. Image by the author, using Slooh.



08:05 UT – Mercury appears 1.4° north of Mars. (Mercury: 81% illuminated, magnitude -1.1, diameter 5.7”. Mars: 99% illuminated, magnitude 1.4, diameter 3.8”. Aries, not visible.)

Mercury fades to magnitude -1.0. (80% illuminated, diameter 5.7”. Aries, not visible.)

The face-on spiral galaxy M101 culminates at midnight tonight. (Magnitude 7.9. Ursa Major, all night. See images above.)



Events in bold involve objects and/or events that are easily visible with the naked eye.

All times are in Universal Time (UTC). To convert the time to your timezone, click here.

Learn more about upcoming astronomical events in 2015 An Astronomical Year (Kindle Edition) and The Astronomical Almanac (2015-2019) (Kindle Edition and Paperback Edition) and 2016 An Astronomical Year (North American Kindle Edition.)

The Amateur Astronomer’s Notebook allows astronomers to log 150 observing sessions and includes an appendix of hundreds of suggested deep sky objects.

Details of all available books across the world can be found here or by visiting the author’s page on Amazon.

If you have any comments or questions, please feel free to contact me at astronomywriter “at”

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