We have posted before about the blue moon, which is the name given to the second full moon appearing in any given month. Tonight, September 30th in the Western hemisphere, there will occur the darker version of the blue moon — a black moon. A black moon is whenever there are two new moons in a given month. This black moon will officially occur on Friday, Sept. 30, at 8:11 p.m. Eastern Time (5:11 p.m. Pacific Time).

Don’t rush outside to see it, the new moon is the moon phase where the moon is entirely in the earth’s shadow, so it is dark. There is literally nothing to see.  Black moons are moderately rare, occurring about once every 32 months.

For those in the Eastern hemisphere, the new moon will rise on October 1, making it the first new moon rather than the second. Rather than encountering a black moon in September, those in Asia, Japan, Australia or New Zealand will have a black moon on October 31, which happens to be Halloween. That should make for an even slightly spookier evening.