Thanks to the New York Times for this reminder:
The Supermoon and Other Moons That Are Super in Their Own Ways
By NICHOLAS ST. FLEUR
Shrug off the supermoon.
Yes, it’s true that on Sunday and Monday nights the full moon will be at its closest to Earth in nearly 70 years. But to the casual observer, it probably won’t look much different from a regular full moon. Yet headlines heralding the event as some sort of don’t-miss spectacle are everywhere.
The supermoon isn’t unique in being sensationalized. Several times every year some sort of catchy-named lunar activity grabs attention, whether warranted or not. That’s how we’ve ended up with must-see events like the blood moon, the black moon, the blue moon, the strawberry moon and the harvest moon, among others.
Though some of these names have historical and cultural origins, many are rooted in folklore and are often overhyped. Below you’ll find an explanation of the science and origins behind some of these events that will let you decide whether they are worth late nights or early mornings of moongazing.
And if you do want to watch the supermoon, the exact time that the moon will be closest will be Monday around 6:22 a.m. Eastern time, but it may shine brighter when the sky is darkest on Sunday and Monday nights.
“The supermoon is a made-up term,” said James Lattis, an astronomer at the University of Wisconsin-Madison. “It’s not an astronomical term, there’s no technical definition of it.”Supermoon was actually coined by an astrologer in the 1970s, not by a scientist. The term has come to loosely mean a full moon that is at perigee, or when the moon is at its closest position to Earth along its orbit.
Now, this definition can vary, which means supermoons can occur multiple times a year, or about once every 14 months, depending on the definition you use. The next so-called supermoon will be on Dec. 14.
The supermoon on Sunday and Monday nights is supposed to be special because it is the closest the full moon will be to Earth since 1948. That means it will be the biggest and brightest full moon in about 68 years. Compared to an average full moon, this supermoon will be approximately 7 percent larger and 15 percent brighter. But most people won’t be able to tell the difference between it and a regular moon.
“There’s no fireworks show, no blinking sign that says, ‘Hey, this is the supermoon!’” said Noah Petro, a deputy project scientist for the Lunar Reconnaissance Orbiter mission.
Instead, the supermoon really shines when it is compared with the full moon at apogee, or its farthest position from Earth. If you place images of the two side by side, you can see the difference more easily, Dr. Petro said. The supermoon is 14 percent larger than the apogee full moon and 30 percent brighter.
On average, the moon is about 238,900 miles away from Earth. But Sunday and Monday’s supermoon will be approximately 221,524 miles away.
Astronomers measure the distance of the moon from Earth by shooting lasers to the surface of the moon, which then bounce off mirrors called retroreflectors, which were left behind by the Apollo missions and two Soviet landers.
Even though most people will not notice anything special about this supermoon, Dr. Petro said it will still be a good excuse to start gazing at the night sky more regularly.
A total lunar eclipse occurs when the moon moves completely behind Earth’s shadow. Recently, this event has given rise to the sinisterly named blood moon, because the moon becomes a dark reddish-brown as it’s consumed by Earth’s shadow.
“A term like that has a number of problems,” Dr. Lattis said. “In the case of a total lunar eclipse, they aren’t always red. The term blood moon not only suggests, it exaggerates.”…
Read the whole article here.