This Sunday night, September 27, we’ll have one of the best lunar eclipses in years. Part of the appeal will be real stuff, part media hype, part folklore. But it really shouldn’t be missed. Here you will find the honest-to-gosh truth, and the cool facts you might want to know.
This is a convenient event. The partial eclipse begins 9:07 p.m. EDT. The black “bite” taken out of the Moon will grow and grow, and then strangely turn red at some point. Best guess for the start of redness: around 9:50; certainly by 10 p.m. When will you see this happen?
The weirdest-looking Moon is not at the start, and not when it’s total. Instead, it’s around 10 p.m., when it takes on its most bizarre shape – not quite totally eclipsed.
The total phase begins at 10:11. Expect to see greatly uneven lighting. The top of the Moon should be much brighter and yellower, with the bottom darker and redder.
Totality ends at 11:24 p.m. EDT, and the visible partial eclipse ends at 12:27 p.m. EDT. You may see other times listed in various media sources. Don’t trust them. Some use “penumbral” eclipse timings, but nothing visible happens then.
Now for the cool extra stuff. This is the night of the Harvest Moon, the year’s best-known Full Moon. The moment of Harvest Moon is mid-eclipse: 10:47 p.m. EDT.
This is also the night of lunar perigee, at 10 p.m. In fact, this is the closest perigee of the year. So, amazingly, as the eclipse is in progress, the Moon arrives at its closest point to Earth of 2015: the largest Moon of the year.
This Moon is 14 percent bigger than this year’s smallest Full Moon, and about seven percent bigger than its average size. This difference is only marginally visible to the eye. It’s more dramatic as an idea than as an actual visual phenom. However, when this Moon first rises (at sunset) it will truly look enormous. But nearly all of that is due to the famous “Moon illusion,” which “blows up” all objects when they’re close to the horizon.
If you’re a numbers person, Sunday night’s Moon will only be 221,753 miles away. That’s the center-to-center separation. The distance from Earth’s surface to the Moon’s nearest surface will then be 216,700 miles. Close!
Will it affect the tides? You bet. We will see the year’s highest tides that day and the next.
As for where in the sky: The eclipsed Moon will hover in front of the faint stars of the constellation Pisces, the Fish. No bright stars or planets will appear near the eclipsed Moon.
Another aspect: This total eclipse is the last of four in a series called a tetrad. The others happened April 15, 2014, October 8, 2014 and April 4, 2015. You see, lunar eclipses can be partial, total or penumbral, and come six months apart, when the node of the Moon’s orbit is aligned with the Earth and Sun. Eclipse types appear in no particular order. So a total is usually followed by a partial, for example. But when four consecutive lunar eclipses are all total, the series is called a tetrad.
Historically, tetrads are rare. During the entire three centuries from 1600 to 1900, there were no tetrads at all. But we are now in a period of frequent tetrads. During the 21st century, there are eight of tetrads. Thus, if considered in terms of our own lifetime, tetrads are rather common.
Still, this tetrad is strange and also fortunate for those living in North America, in that all four total eclipses were at least partly visible from nearly the entire mainland US. The one most conveniently positioned for us who live in the Hudson Valley is this one, of September 27.
Media hype, New Age and religious/Doomsday aspects of this event
For several years now, the media have often referred to a total lunar eclipse as a “Blood Moon.” We can expect to see such headlines again for this eclipse. That label sounds dramatic, but the actual color of the eclipsed moon is coppery red, like a penny, more resembling deep orange, and thus doesn’t look at all like blood.
That allusion feeds into Biblical passages such as Revelation 6:12 and Joel 2:31 (King James Bible):
The Sun shall be turned into darkness, and the Moon into blood, before the great and the terrible day of the LORD come.
This has made a few on the Internet assume that this eclipse heralds Armageddon.
The media have, the past few years, also referred to any Full Moon that happens on the night of lunar perigee (close approach) to be a “MegaMoon.” This is a newly coined term, and is not used by astronomers. Since a Full Moon/perigee coincide once or twice every year, a “big” Full Moon is actually not rare. Such events are generally of little or no interest to professional astronomers.
In fact, a total lunar eclipse is not scientifically useful. It is not like a total solar eclipse, where the appearance of phenomena like the solar corona offer opportunities for serious research. Indeed, even this coming together of Harvest Moon, extreme lunar perigee (close approach) and a total eclipse is a popular astronomy and folklore event rather than a scientifically useful one.
No matter. It’s just plain cool. In terms of folklore and tradition, when do you recall seeing the Harvest Moon get totally eclipsed? And when is the Moon eclipsed just as it reaches its closest position to Earth of the whole year? The combination gives it a huge “wow” factor.
Let’s hope for clear skies.