Sunday, Sept. 27, will bring the second of this year’s three supermoons, as well as the closest full moon of the year (a super-duper moon?). Most exciting of all is that a full lunar eclipse will take place at the same time. This dual event hasn’t happened since 1982 and won’t happen again until 2033.

To get the full effect of the supermoon, go right at sunset (when full moons rise) to a place where the horizon isn’t too obscured by trees. Thanks to an optical illusion, the full moon always seems much larger when it’s close to the horizon.

The lunar eclipse has a leisurely timeframe of a few hours, so you can check on it periodically to watch the moon turn different shadowy shades of red and gray. Lunar eclipses can last up to three hours and 40 minutes, with totality lasting for as long as an hour and 40 minutes. The eclipse is set to begin at 9:07 p.m. Eastern Time and totality will begin at 11:11 p.m.

You’ve probably seen the emails and Facebook posts heralding the coming of various supermoons and going on about how much larger and brighter the moon will appear. Same with the Mars hoax posts that claim Mars will appear as large as the full moon. That would be incredibly cool, and it would make observing the red planet much easier, but it’s never going to happen.

Supermoons do have an enticing quality to them, however, and they really can look slightly larger (up to 14 percent) and brighter (up to 30 percent). Whether noticing a marked difference is accurate perception or the result of an active imagination may never be confirmed.

The moon has an elliptical, or oval-shaped, orbit, and its distance from Earth each month falls between approximately 222,000 miles and 252,000 miles. Most nights it’s somewhere between that.

The term “supermoon” was coined by astrologer Richard Nolle in 1979 and defined as a new or full moon at or within 90 percent of its closest approach to Earth (perigee) in a given orbit. In astronomical terms, a supermoon is the combination of perigee and syzygy, when Earth, the moon, and the sun are all aligned, which is the case during every new or full moon. In fact, the astronomical term for a supermoon is the less slick-sounding tongue-twister “perigee-syzygy.”

There’s also something called a micromoon. As you can probably guess, it’s when a full or a new moon takes place at the same time the moon is farthest from the Earth, or at its orbital apogee.

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Sky calendar

Sept. 13: New moon.

Sept. 23: September Equinox. The sun will shine directly on the equator, bringing nearly equal amounts of day and night throughout the world. This is also the first day of fall (autumnal equinox) in the Northern Hemisphere and the first day of spring (vernal equinox) in the Southern Hemisphere.

Sept. 27: Supermoon. This full moon was known by early Native American tribes as the Full Corn Moon because the corn was harvested around this time of year. This moon is also known as the Harvest Moon, the full moon that occurs closest to the September equinox each year. The moon will be at its closest approach to the Earth and may look slightly larger and brighter than usual. This will be the closest full moon of the year.

Sept. 27: Total lunar eclipse. A total lunar eclipse occurs when the moon passes completely through Earth’s umbra (shadow), gradually turning the moon darker and then a rusty or blood red color. The eclipse will be visible throughout most of North and South America, Europe, Africa and western Asia.