Pi day, which was designated by the U.S. House of Representatives in 2009, celebrates the well-known mathematical constant Pi (π). For you non-geeks, Pi Day is 3/14 because the first three digits of the mathematical constant pi, which is the ratio of a circle’s circumference to its diameter, are 3.14.
As midnight approaches tonight, look to the east for the bright star Arcturus. At magnitude 0.0, it is the second-brightest star visible from mid-northern latitudes.
If you scan about 20° to the left and a little below this luminary, you should see a conspicuous semicircle of stars: the constellation Corona Borealis the Northern Crown.
This small constellation is the most prominent group of stars having a shape reminiscent of a circle, and it makes it an ideal target for Pi Day — a day where we celebrate all things circular.
For more quick and easy observing tips, check out The sky this week for March 8 to 17.