Home PageAstronomy ArticlesStars PageAstronomy Links


Closest Full Moon of 2011 on March 19


The closest Full Moon of the year will fall on March 19, 2011. Since it's the closest Full Moon, it'll also be the year's largest Full Moon. Watch it usher in extra large spring tides along the ocean shorelines.

Enter Lunar Apogee and Lunar Perigee

Full MoonDuring the course of one month, the Moon's distance from Earth varies by about 50,000 kilometers (30,000 miles). For instance, the Moon will swing to apogee - its greatest distance for the month - on March 6, at which time the Moon will be 406,583 kilometers away. Nearly two weeks later, on March 19, the Moon will be at perigee - its closest point to Earth for the month - with the Moon residing at 356,575 kilometers.
Photo Credit: bilbord99

Full Moon Aligns With Lunar Perigee

March 2011 presents the only time this year that the Full Moon will fall on the same date as lunar perigee. Additionally, this particular March 19, 2011 perigee gives us the closest perigee of the year. As a rule of thumb, the year's closest perigee happens on the day that the Full Moon and perigee most closely coincide. (It's possible for the year's closest perigee to coincide with the New Moon, though it's fairly uncommon.)
As a matter of fact, this will be the closest that the Moon swings to Earth since December 12, 2008. What's more, the Moon won't come this close again until November 14, 2016. Like in 2011, these extra-close Moons in 2008 and 2016 also occur on the day on which the Full Moon and perigee most closely align. (For more, check out John Walker's cool perigee calculator.)

Closest Full Moons Come in Cycles of 14 Lunar Months

When will the closest Full Moon happen again? It'll happen on the 14th Full Moon after this March 2011 Full Moon because closest Full Moons recur every 14 lunar (synodic) months.
A lunar month refers to the period of time between successive Full Moons, a period of 29.53059 days. An anomalistic month is the measure of time between successive perigees, a period of 27.55455 days.
Amazingly enough, 14 lunar months almost exactly equal 15 anomalistic months:
14 x 29.53059 = 413.428 days
15 x 27.55455 = 413.318 days
This time period is equal to about 1 year 1 month and 18 days. Next year, the Full Moon and perigee will realign on May 6, 2012 by Universal Time. However, for the clocks in the United States time zones, this Full Moon will realign with perigee on May 5, 2012.
Incidentally, the Full Moon on March 19, 2011 falls at 18:10 (6:10 p.m.) Universal Time. That's 2:10 p.m. Eastern Daylight Time, 1:10 p.m. Central Daylight Time, 12:10 p.m. Mountain Daylight Time and 11:10 a.m. Pacific Daylight Time.

copyright 2011 by Bruce McClure

Lunar Perigee and Apogee Calculator

All Perigee Full Moons in the 21st Century

February 2011 Feature * April 2011 Feature