October Full Moon 2018: Hunter's Moon Swings by Uranus

The full moon of October, called the Hunter's Moon, will grace the skies this week on Wednesday (Oct. 24), making a close pass by Uranus — though the faint planet will be difficult to see against the lunar glare. 

The moon becomes officially full on Oct. 24 at 11:45 a.m. EDT (1545 GMT), according to NASA's SkyCal. For observers in New York City, the near-full moon will rise on that day at 6:30 p.m. local time and set the next morning at 8:02 a.m., according to the U.S. Naval Observatory (USNO). The moon will be in the constellation Cetus and will rise about 28 minutes after sunset (which will happen at 6:02 p.m., per the USNO). 

The close pass to Uranus will happen a day after that planet reaches opposition on Oct. 23. Opposition is when the Earth is directly between an outer planet and the sun. At that point, the planet (Uranus, in this case) and the sun appear to be on the exact opposite sides of the sky. During oppositions, planets are at their brightest and easiest to observe, because they are above the horizon all night long in most locations. [How to See Planet Uranus in the Night Sky]

This sky map shows where to find Uranus when the planet is at opposition on Oct. 23, 2018, at 8:33 p.m. EDT (0033 GMT on Oct. 22), as seen from New York City (41 degrees latitude).
(Image credit: SkySafari app)

On Oct. 24, Uranus will rise at 5:58 p.m. in New York City, according to heavens-above.com calculations, just 4 minutes before the moon does. At magnitude 5.7, Uranus is faint, but just visible with the naked eye in a dark-sky location. However, with the full moon close by — less than 8 degrees at the closest — Uranus will be washed out to naked-eye observers. Catching Uranus will be easier as the moon wanes in the following days. 

Other outer planets will join the moon in the sky on Oct. 24. New York City observers will see Mars rise at 3:10 p.m. and set at 12:58 a.m. on Oct. 25, so when the full moon rises it will be about 21 degrees above the eastern horizon in the constellation Capricornus (the sea goat). Capricornus is a relatively faint constellation, so the planet will stand out because of its distinct reddish color and its brightness — it will be about magnitude -0.8, comparable to the star Vega. At moonrise, close to sunset, the sky will likely be too bright for observers to spot Mars, but within an hour, the sky will darken enough to make the Red Planet more easily visible. 

As observers turn their gaze westward, they will see the planet Saturn; at an hour after sunset, it will be about 20 degrees up and in the southwestern sky, in the constellation Sagittarius. Saturn will be fainter than Mars and, as usual, will have a distinct yellowish hue. Jupiter will also be in the western sky, but much closer to the horizon at sunset (only 11 degrees high). That will make the giant planet hard to see until the sun is well below the horizon, but Jupitersets only about an hour after sunset on Oct. 24 (at 7:13 p.m. in New York). 

Mercury and Venus are both only a few degrees away from the sun, and for naked-eye skywatchers, the two planets are effectively invisible, because the sun's glare will overwhelm them. Venus will reach inferior conjunction, the point where the planet is directly between the sun and Earth, on Oct. 26, rendering Earth's neighbor invisible to us. Planets at inferior conjunction aren’t visible because they are at the same celestial longitude as the sun; to see them one would have to block the sun’s light completely (this actually happens during total solar eclipses). The planet will also set about 30 minutes before sunset on Oct. 24. Mercury, meanwhile, will set 40 minutes after the sun does, and at sunset on that same day, the innermost planet will be a mere 6.7 degrees above the horizon. 

The full moon tends to overwhelm the fainter stars. But late October offers some bright constellations that are visible even in light-polluted areas. For example, as the full moon rises higher, Taurus and Orion will appear near the eastern horizon; by midnight, those two will be high enough to clear most buildings and trees. Meanwhile, in the west, the summer constellations, such as Lyra, Cygnus and Aquila, will be setting. 

The full Hunter's Moon sets over the Bear River Valley in southwest Wyoming.
(Image credit: Katie Theule/USFWS)

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. 

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. Cree people called it "Pimahamowipisim" (Migrating Moon), as in northeastern North America, many bird species start migrating south for the winter at the time of this moon. 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.  

In the Southern Hemisphere, October means days are 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.

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