A full moon rises behind the Empire State Building in New York in April 2012. This weekend, a supermoon will rise over the USA.(Photo: Julio Cortez, AP)
Doyle Rice, USA TODAY
Moon maniacs, this is your weekend.
A so-called supermoon will rise in the east at sunset on Saturday.
A supermoon occurs when the moon is slightly closer to Earth than it typically is, and the effect is most noticeable when it occurs at the same time as a full moon, according to James Garvin, chief scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.
This full moon is not only the closest and largest full moon of the year, according to astronomy website EarthSky. It's also the moon's closest encounter with Earth in all of 2013. So it's not just a supermoon - it's the closest supermoon of the half-dozen or so that will occur this year, EarthSky reports.
According to 2 On Your Side meterologist Mary Beth Wrobel, the supermoon was at its biggest and boldest at 7:32 a.m. Eastern Time on Sunday.
The word supermoon was coined in 1979 by astrologer Richard Nolle, says AccuWeather's Mark Paquette. Nolle used the term to describe a new or full moon that occurs when the moon is at or near its closest approach to Earth.
The moon will pass within about 221,000 miles from the Earth on Saturday night, compared with its "typical" distance of about 238,000 miles.
Garvin says the moon may seem bigger, although the difference in its distance from Earth is only a few percent. For instance, the moon on Saturday night will appear 12% to 14% larger than it will next month.
The moon's effect on ocean tides is higher during a supermoon than any other time, so expect higher and lower tides than usual, reports Sean Breslin of the Weather Channel. (The high tide this weekend is also known as a "king" tide.) There is no connection between the supermoon and earthquakes, according to the U.S. Geological Survey.
"If you're looking for a more thrilling lunar event, a larger supermoon is expected on Sept. 28, 2015, and the largest supermoon until 2034 will occur on Nov. 14, 2016," Breslin says.
The Desert Southwest and the lower Ohio Valley into the mid-Atlantic and southern New England will have the clearest skies for viewing the supermoon, according to a forecast from AccuWeather.
The Upper Midwest will have the poorest conditions, since rain and thunderstorms are forecast across that region overnight, AccuWeather reports. Showers will also affect part of the Northwest and pockets of the Plains and Deep South, but will die out as the night goes on. The rest of the USA will have times of clear skies with patchy clouds obstructing views at times.