Why extremely rare events keep happening all the time
Something weird seems to be happening in the heavens. This week marks a coincidence of the full moon and the summer solstice. Some astronomers are calling this combination of maximum moonlight and the Northern Hemisphere's longest day a rare event. It comes close on the heels of last month's rare passage of Mercury in front of the sun, September's rare pairing of a lunar eclipse with a so-called supermoon, the rare 2014 "tetrad" of lunar eclipses, the rare 2012 transit of Venus...