Black moon rising: Friday's rare lunar event explained
No, it鈥檚 not some forgotten Creedence Clearwater Revival B-side. The upcoming black moon, which rises Friday night, is a bona-fide lunar event.
Well, sort of.
In some ways, a black moon is the opposite of a blue moon. When a full moon rises twice in a month, the second one is called a blue moon. Similarly, a black moon is the second new moon in a single month. It鈥檚 a somewhat rare event, only coming around about once every 32 months; the last one occurred in March 2014.
In the Western hemisphere, the black moon will rise on September 30. Those on the other side of the planet won鈥檛 see it until October 1st, so technically it won鈥檛 be that month鈥檚 black moon. However, the Eastern hemisphere will get a black moon later that month with the rising of a second new moon 鈥� right around Halloween, as it happens.
The black moon by itself isn鈥檛 much of a spectacle. As with any new moon, the black moon will be pretty much invisible no matter where you watch it from. But the darkened sky will provide an excellent backdrop for stargazing.
This week鈥檚 black moon is the latest in a slew of seemingly special lunar events 鈥� blue moons, blood moons, supermoons and more. But the truth is many of them aren鈥檛 all that uncommon, and astronomers don鈥檛 even recognize them as separate phenomena.
So why do we make such distinctions?
Many are actually a relic of seasonal timekeeping practices. The harvest moon, which like all full moons rises just as the sun sets, got the name because it comes at the time of year when farmers could use extra light in the evening to bring in their harvests. The full buck moon corresponds to the time of year when young deer begin to sprout horns. Then there鈥檚 the strawberry moon, the sturgeon moon, the hunter鈥檚 moon 鈥� you name it, there鈥檚 a moon for it.
鈥淔ull moon names date back to Native Americans, of what is now the northern and eastern United States,鈥� skywatching columnist Joe Rao wrote for SPACE.com in 2014. 鈥淭hose tribes of a few hundred years ago kept track of the seasons by giving to each recurring full moon. Their names were applied to the entire month in which each occurred.鈥�
Nowadays, the practice has more to do with PR than practicality. It鈥檚 just easier to generate public interest for celestial events when they have a catchy name like 鈥渟upermoon.鈥� A supermoon occurs when a full moon is in perigee, orbiting at its closest point to Earth. The term, , only dates back to 1979 and didn鈥檛 become popular until 2011.
