August full moon 2021: The ‘Sturgeon Moon’ swings by Jupiter this weekend

The full moon of August arrives Sunday (Aug. 22), after it makes a close pass to Jupiter. 

The moon will officially become full at 8:02 a.m. EDT (1202 GMT), according to NASA. For New York City observers, the just-past-full moon will rise at 8:20 p.m. local time, or about 40 minutes after sunset that day. 

A full moon happens when the moon is exactly on the opposite side of the Earth from the sun — if you measured the angle across the sky from the sun to the moon it would be 180 degrees. If the moon passes through the Earth’s shadow we see a lunar eclipse, but that doesn’t happen each month because the moon’s orbit is inclined about 5 degrees to the plane of the Earth’s orbit, so the moon often “misses” the shadow. 

Related: Jupiter is at its biggest and brightest this week

On Aug. 22, just after midnight, the almost-full moon will appear close to Jupiter, passing within about seven lunar diameters of the planet, or 3 degrees and 44 arcminutes, according to the skywatching site In-the-Sky.org. The two bodies will be in conjunction — sharing the same celestial longitude — at 12:56 a.m. EDT (. Both will be in Capricornus, a faint constellation that makes Jupiter that much easier to identify; at the moment of conjunction Jupiter will appear above and slightly to the left (east) of the moon. The moon will be to the south, nearing its maximum altitude of about 31 degrees above the horizon. The moon becomes officially full some hours later, but it will have already set by that point (moonset is at 6:01 a.m. in New York City). 

As one moves south, the conjunction will appear higher in the sky; from Miami the conjunction will be about 46 degrees above the horizon. In the Southern Hemisphere the nights are longer (as it is winter there) and the moon will appear correspondingly higher still. From Buenos Aires, the full moon occurs at 9:01 a.m. on Aug. 22, and rises the evening of Aug. 21 at 5:36 p.m. local time. The conjunction will be at 1:56 a.m. on August 22 and the pair will be about 69 degrees high at 12:42 a.m. 

Visible planets

On the night of the full moon, Venus, Mercury and Mars will all be “evening stars.” The three planets respectively rise at 9:28 a.m., 7:51 a.m. and 7:33 a.m. Eastern Time on Aug. 22 in New York, according to Heavens-Above.com calculations. 

But only Venus will be readily observable; by 8 p.m. Mars will be no more than 4 degrees above the western horizon, and Mercury only at about 5 degrees high in New York. That makes them very challenging to see, and both planets will have set by 8:30 p.m. Venus, however, is bright enough that it will stand out against even a still-light sky just after sunset. At an altitude of about 13 degrees by 8 p.m., the planet does not set until 9:13 p.m. 

Other planets will be rising — Jupiter will be near the moon, just rising in the east after sunset. Saturn will rise at 6:43 p.m. local time in New York City and be in Capricornus. At the time the moon rises it will be about 15 degrees above the southeastern horizon, with Jupiter to its left. 

Stars and constellations 

Although the full moon tends to overwhelm the fainter stars, asterisms such as the Summer Triangle — which consists of the stars Vega, Deneb and Altair — will be prominent and easily spotted, high in the east-southeast. About an hour and a half after sunset in the Northern Hemisphere, you can look nearly straight up to find Vega, which, at mid-northern latitudes, is at an altitude of between 80 and 88 degrees (depending on how far north or south you are in the lower 48 states). 

By about 9:30 p.m. local time in mid-northern latitudes the constellation Scorpius, the scorpion is visible in the south-southwest. Scorpius can be spotted by looking for Antares, a bright reddish star that marks the heart of the scorpion. To the left of Scorpius is the constellation Sagittarius, the archer, with its distinctive teapot shape, and above Scorpius is Ophiuchus, the snake handler and healer. 

Ursa Major, the Great Bear, will be in the northwest after sunset and as one follows the “pointers” — the two stars in the front of the Big Dipper’s bowl — to Polaris, one can keep going and hit the W-shaped constellation Cassiopeia. Using the handle of the Dipper, one can “Arc to Arcturus” by sweeping along the handle until you hit the eponymous star in Boötes, the herdsman. 

In the Southern Hemisphere, the sky is “upside down” and by 9 p.m. local time on Aug. 22 at the latitude of Cape Town or Melbourne one will see the full moon, Jupiter and Saturn forming a rough vertical line in the east, with the moon at the bottom and Saturn at the top. Just west of them, to the right, one will see Piscis Austrinus, the Southern Fish, and the bright star Fomalhaut, which is known for being relatively close — only 25 light years distant and the first star to have an exoplanet seen in visible light. As one turns south one sees Achernar, the brightest star in Eridanus the river. High in the southwest one can see the Southern Cross and just above it the Centaur, home to Alpha Centauri. 

How the Sturgeon Moon got its name

The full moon of August, according to the Old Farmer’s Almanac, is sometimes known as the Sturgeon Moon. The name likely came from both colonists and Algonquian-speaking peoples in northeastern North America, as sturgeon (a type of fish) are native to both Europe and the Americas. 

Not all Native nations in the region used the term. The Ojibwe, whose traditional territory is near the Great Lakes, referred to the eighth full moon of the year as the Blackberry Moon, which could also occur in July. The Cree of Ontario called the August full moon the Flying Up Moon because it was when young birds would fledge. In the Pacific Northwest, the Haida called it the Salmon Moon (“chíin kungáay”), according to Dolly Garza’s book “Tlingit Moon & Tide.” 

Related: Full moon names (and more) for 2021

In China and many surrounding countries, the August full moon marks the Hungry Ghost Festival. The Chinese calendar is lunisolar, and strictly speaking the August full moon falls in the seventh month, Qiǎoyuè, or Skill Month. It is also called Ghost Month. The festival is to honor spirits who were not given proper funerals or offerings when they died. People light paper lanterns and burn paper versions of earthly possessions or (fake) money to honor the departed. 

The Māori counted lunar months from new moon to new moon, so the August full moon is halfway through the month of Mahuru, which is towards the latter part of the austral winter. The month is described as “The Earth has now acquired warmth.” 

In South Africa, the Zulu call the first full month of the year uNcwaba (the small c marks a clicking sound in Zulu), and the name is derived from describing a man who has made “a new appearance” after a long journey when he washes and anoints himself with fat; in a similar vein the Earth puts on a new appearance in spring. 

Editor’s note: If you snap an awesome photo of the moon or the lunar eclipse that you’d like to share with Space.com and our news partners for a potential story or gallery, send images and comments to managing editor Tariq Malik at spacephotos@space.com.

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