Bob Moler's Ephemeris Blog

This is Bob Moler with Ephemeris for Pi Approximation Day*, Monday, July 22nd. Today the Sun will be up for 15 hours exactly, setting at 9:19, and it will rise tomorrow at 6:19. The Moon, 1 day past full, will rise at 10:37 this evening.

The first Pi day of the year for mathematics junkies was March 14th utilizing the three most significant digits of the mathematical value π, the ratio of the circumference of a circle to its diameter, written as 3.14. Today is the second version of π written as the fraction 22/7. We don’t write our date that way, we write it as 7/22. In other parts of the world it is written as 22/7. So whichever way you slice it, it’s a pi day and in Northern Michigan I would imagine it’s a cherry pi. In the sky today the planet Mercury is at its greatest elongation or separation east of the Sun in the western sky. It is preceding the Sun heading southward against the stars and is not easily visible after sunset.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT–4 hours). They may be different for your location.

* In the radio program I called it Pi Day #2. I have since found out that today has a special name.

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