The full moon of October, called the Hunter's Moon, will grace the skies this week on Sunday (Oct. 13), a few days after reaching apogee, the farthest point in its orbit from Earth. It will be the "smallest" full moon of the year, but you likely won't notice the difference with your unaided eye.
The moon becomes officially full on Oct. 13 at 5:08 p.m. EDT (2108 UTC), according to the U.S. Naval Observatory’s data. For observers in New York City, the near-full moon will rise on that day at 6:40 p.m. local time and set the next morning at 7:35 a.m. As it rises about 21 minutes after sunset (which will happen at 6:19 p.m., per the USNO) the moon will be in the constellation Pisces.
On Oct. 10 the moon was as far from Earth as it ever does during its roughly 29-day orbit; at 2:29 p.m. EDT (1829 GMT) it was 252,214 miles (405,899 kilometers) from the Earth. The average distance of the moon is 239,000 miles (385,000 km) from the center of the Earth.
At perigee, the closest point in its orbit, the moon will be 224,508 miles (361,311 kilometers) from Earth's center; it will reach that point on Oct. 26 at 6:40 a.m. EDT (1040 GMT). Perigee and apogee occur because the lunar orbit is not perfectly circular. It's shape is an ellipse, though it’s close enough to a circle if one were to draw it on a piece of standard typing paper to scale the difference would be measured in millimeters. So this full moon will be slightly smaller than usual, though not enough for the casual observer to notice.
Planets and stars, too!
Besides the moon, a few planets will be visible in the sky on Oct. 13., though for the traditional naked-eye planets the best viewing times will be just after sunset and just before sunrise. Note: The times below are listed for Eastern Daylight Time, check your local forecast, or an astronomy software program or app like SkySafari, for your local conditions.
As the moon is coming over the horizon in the east Mercury and Venus will both be in the evening sky, though they both set within a half hour of the sun; on Oct. 13 Venus sets at 6:57 p.m. and Mercury at 7:01 p.m. At 6:30 p.m. – only 11 minutes after sunset – Mercury’s altitude is 5.6 degrees above the horizon while Venus is 4.8 degrees, according to heavens-above.com calculations. That makes them very difficult to spot as the glare of the sun will still be evident. (Observers should note that looking for either planet around sunset can be dangerous; it's a good idea to wait until the sun gets below the horizon. One should never point an unfiltered pair of binoculars or a telescope close to the sun).
Mercury gets easier to see in the days following the full moon; each day it sets a little later. On Oct. 20 the planet reaches greatest eastern elongation – the furthest it gets from the sun from the point of view of Earth. On that day, New York City observers will see Mercury set at 6:55 p.m., while the sun sets at 6:08 p.m. It is still only 4.1 degrees above the horizon at 6:30 p.m., so it will be hard to spot nonetheless.
More southerly sky watchers will have a slightly easier time catching the inner planets. In Miami, on the night of the full moon, the sun sets at 6:55 p.m., and Mercury sets at 7:57 p.m., so by 7:30 p.m., the sky is getting dark enough to more easily see Mercury, which will be about 5.5 degrees up. At about the same time Venus will be at an altitude of 2.5 degrees, so it will only be visible if one has a clear view and a flat horizon – over the ocean, for example. Venus sets at 7:42 p.m.
Mars, meanwhile, will be in the constellation Virgo. It won't be visible until just before dawn on Oct. 13; the planet rises at 5:57 a.m. in New York; the sun rises an hour later at 7:04 p.m. That means Mars will be only about 6 degrees above the horizon at 6:30 a.m. – difficult to see but not impossible with a relatively clear eastern horizon.
Other outer planets will join the moon in the sky on Oct. 13. New York City observers will see Jupiter and Saturn in the southwestern sky in the evening. New York City observers will see them respectively set at 9:18 p.m. and 11:04 p.m. Eastern time. At about a half an hour after sunset the planets will be appear grouped together with Jupiter on the right and Saturn on the left, with Jupiter about 15 degrees above the horizon and Saturn 25 degrees. Saturn will be in Sagittarius while Jupiter is in the constellation Ophiuchus.
Looking up from the two planets observers will see Altair and Vega, which form part of the Summer Triangle. In the Northern Hemisphere the Summer Triangle stars are fading from view; after midnight in October they are low in the western sky. Turning northward form Jupiter and Saturn one will see Arcturus, in the constellation Boötes, which in mid-northern latitudes will be in the northwest.
As the moon rises in the east one can trace a path westward — this will take your eye "above" the moon — and reach the Great Square asterism which marks the constellations Pegasus and Andromeda. Andromeda contains the Andromeda Galaxy, M31, but with a full moon that's a harder object to see.
While the full moon tends to overwhelm fainter stars, there are some bright constellations that start to become prominent in October. Orion and Taurus, which are better known for appearing in winter, but both are above the horizon in the east by midnight.
The Hunter's Moon Explained
The October full moon is often called the Hunter's Moon, according to the Old Farmer's Almanac, because that moon occurs when the season for hunting many game animals begins. Traditional names for the full moon often reflect local environment and history; according to the Ontario Native Literacy Coalition, the Ojibwe people called October's full moon the "Mskawji Giizis," or the Freezing Moon, because October is when the first frosts occur in their traditional territory in the Great Lakes region. The Cree people called it "Pimahamowipisim" (Migrating Moon), as in North America, many bird species start migrating south for the winter in mid-autumn.
In the Pacific Northwest, the Tlingit called the October full moon "Dís Tlein" (Big Moon), while the Haida called the moon "Kalk Kungaay," or the Ice Moon, according to the "Tlingit Moon and Tide Teaching Resource" published by the University of Alaska Fairbanks.
Southern Hemisphere peoples’ names for the moon reflected the change of seasons from winter to summer and days getting warmer and longer. The Māori of New Zealand called the lunar months of October to November (measured from new moon to new moon) "Whiringa-ā-rangi," meaning, "It has now become summer, and the sun has acquired strength," according to the Encyclopedia of New Zealand.