Supermoon, total lunar eclipse coming to Long Island

Call it a supermoon with a total lunar eclipse -- and then some.

It's hard to fathom the descriptors tagged to the full moon expected Sunday, just about when the sun sets.

First, it's to be "the biggest and closest supermoon of the year," said EarthSky.org, which offers daily updates on the night sky. The supermoon term is elicited when a full moon appears supersized as a result of its coming closest to Earth in its elliptical orbit.

Such moons occur about once a year and can appear as much as 14 percent larger and 30 percent brighter than typical full moons, according to NASA.

It's also called a "blood moon," because a total lunar eclipse is also expected Sunday night.

When a full moon -- in this case, a super full moon -- enters total eclipse, it can appear red. That happens as sunlight moves through Earth's atmosphere and its sunrises and sunsets get projected onto the moon, says Sue Rose of East Meadow, president of the Amateur Observers' Society of New York.

The larger-than-usual bright, white moon will darken as it moves into Earth's shadow before turning a reddish hue at total eclipse. It will gradually darken again and revert to white.

Long Islanders "are very lucky in that we get to see the entire process from start to finish. . . . As long as you have a reasonably good view of the east, you will see the entire eclipse without having to travel to a special location," Rose said.

"Since it occurs at a reasonable time, maybe parents will let their younger family members stay up late to watch the spectacle of celestial mechanics in action," she said.

The last time "planetary dynamics" lined a supermoon up with a lunar eclipse was in 1982, and the next one won't arrive until 2033, according to a Nasa.gov post.

And there's more: It's also a harvest moon, which is a full moon that comes nearest to the autumnal equinox, which is Wednesday, the first day of fall.

The National Weather Service predicts mostly clear skies for Sunday night.

Here's a viewing schedule provided by Rose:

Moon starts rising due east, Sunday, 6:34 p.m.

Partial eclipse begins with left side of moon starting to darken, 9:07 p.m.

Total eclipse begins with moon completely within dark shadow of Earth, 10:11 p.m.

Maximum eclipse, with moon, now red, in the center of the shadow, 10:47 p.m.

Total eclipse ends, with moon starting to darken, 11:23 p.m.

Partial eclipse ends, moon back to white, 12:27 a.m., Monday, Sept. 28.