Super Blood Moon? Sunday to Bring Rare 'Supermoon' Lunar Eclipse

9-23-15 Blood moon
A shadow falls on the moon as it undergoes a total lunar eclipse, as seen from Mexico City on April 15, 2014. On September 27, a lunar eclipse will occur at the same time as a supermoon for the first time since 1982. Edgard Garrido/Reuters

The full moon Sunday will appear larger, brighter and redder than usual as it reaches its closest point to the Earth. As it so happens, it will also be going through a lunar eclipse. The two events—the so-called "supermoon" and the eclipse—have occurred in tandem only five times since the turn of the 20th century, with the most recent in 1982. After Sunday's event, the next super moon lunar eclipse is expected in 2033.

As NASA explains in an animated preview video published last month, a "supermoon" is a result of the moon's elliptical orbit. The moon reaches the point farthest from the Earth at its apogee, and the closest point to the Earth at its perigee. A perigee full moon—when it is 31,000 miles closer to Earth than at its apogee—appears 14 percent larger and 30 percent brighter than an apogee full moon.

A lunar eclipse occurs when the moon is directly opposite the sun, with the Earth in the middle. The Earth's shadow blocks light from the sun that normally reflects directly off the moon. Instead, light refracts around the edges of the Earth to give the moon the reddish-orange glow of sunset. That's why this event is sometimes referred to as a "blood moon."

Before people understood why an eclipse actually occurred, it constituted a rather terrifying phenomenon. "It looked like one heck of an omen in the sky," says Alan MacRobert, a senior editor at Sky & Telescope. "I mean the moon turning to blood—how could anybody think this means good news?"

Even today, some claim vociferously that a blood moon portends doom, like John Hagee, founder and senior pastor of a San Antonio megachurch and author of the 2013 book Four Blood Moons. "Every heavenly body is controlled by the unseen hand of God, which signals coming events to humanity. There are no solar or lunar accidents," reads the description of a video promoting the book. Rumors in the vein of Hagee's warnings have reportedly suggested that an asteroid due to hit the Earth sometime between September 15 and 28, and coinciding with the supermoon lunar eclipse, will end life on the planet.

MacRobert says this isn't the first (and likely not the last) time such erroneous claims have been made or spread quickly, especially on the Internet in recent years. "I don't think there's been a month or a year that's gone by in the last decades," he says, "that some loony tune hasn't created a stir by saying he's discovered a secret asteroid that's going to hit the Earth next month and nobody knows about it but him. And it's amazing how gullible people are."

Instead of allowing themselves to be consumed by ominous predictions, MacRobert says, people should defer to an authoritative source with expertise in asteroids. Paul Chodas, manager of NASA's Near-Earth Object office, says in an August news release that "there is no scientific basis—not one shred of evidence—that an asteroid or any other celestial object will impact Earth on those dates [September 15-28]." His group identifies and predicts the paths of asteroids that could potentially pose a threat to our planet.

"If there were any object large enough to do that type of destruction in September, we would have seen something of it by now," Chodas says. "In fact, not a single one of the known objects has any credible chance of hitting our planet over the next century."

With irrational fears dispelled, people can watch what MacRobert calls this "rather beautiful and dramatic illustration of the cycles of astronomical bodies" without any optical equipment, though if you own a pair of binoculars or an amateur telescope, this is the right time to take it down from the shelf.

The super moon lunar eclipse will be visible from North and South America, Europe, Africa and parts of West Asia and the eastern Pacific, according to NASA. MacRobert says the event is visible to the naked eye for anyone with an unobstructed view of the eastern sky and clear weather (clouds could get in the way). The eclipse takes place in phases, with the total lunar eclipse beginning at 10:11 p.m. ET and ending at 11:23 p.m. Sky & Telescope has created a timetable that can be used to determine when each stage begins in different time zones.

"Things like this remind you that there's a big universe out there," MacRobert says. "If you turn your head up from our busy little lives here on this planet, there are much greater, grander, more enormous happenings out there."