Water Jar Asterism in Aquarius Rises in Southwest in Northern November

Summary: The four star Water Jar asterism in Aquarius the Water Bearer constellation rises in the southwest in the Northern Hemisphere's November.

Water Jar asterism in Aquarius the Water Bearer constellation, depicted by Sidney Hall in Urania’s Mirror (1825), a set of 32 astronomical star chart cards: U.S. Library of Congress, Public Domain, via Wikimedia Commons

The four star Water Jar asterism in Aquarius the Water Bearer constellation rises in the southwest in the late autumn skies of November in the Northern Hemisphere.

The southern celestial hemisphere primarily claims Aquarius the Water Bearer. The constellation’s iceberg-like location slips slightly north over the celestial equator but largely stretches southward across the celestial sphere, the imaginary sphere projected outward from Earth.

The four star Water Jar asterism in Aquarius the Water Bearer constellation lies near asterisms in two northern neighbors. The Great Square of Pegasus perches above the Water Jar asterism, to the northeast. The Circlet of Pisces resides to the side, to the east-northeast.

Aquarius the Water Bearer’s Water Jar asterism occupies the constellation’s upper reaches. The four star Water Jar asterism straddles the celestial equator, the imaginary great circle projected outward from Earth’s equator onto the imaginary, Earth-centered celestial sphere.

The Water Jar asterism is often described as a y-shaped quartet centering on Zeta Aquarii. Other configurations exist. The official constellation chart for Aquarius released by the International Astronomical Union (IAU), in collaboration with Sky & Telescope magazine, presents the asterism with a four-angled, kite-shaped outline that fans eastward from Alpha Aquarii, usually depicted as marking the Water Bearer’s shoulder and that excludes Eta Aquarii.

In the y-shaped quartet, Gamma Aquarii (γ Aquarii; Gamma Aqr; γ Aqr) marks the asterism’s southernmost point. The fourth magnitude binary star system anchors the y-shaped configuration’s tail. Gamma Aquarii shines as the y-shaped asterism’s second brightest star.

Gamma Aquarii’s traditional name is Sadachbia, which derives from an Arabic phrase meaning “luck of the tents” (Arabic: sa’d al-‘axbiyah). Arab astronomy groups Gamma Aquarii and the y-shaped configuration’s other three stars as components of “the tent” (Arabic: al Aḣbiyah).

Pi Aquarii (π Aqr; π Aquarii) perches slightly northeast of Gamma Aquarii. The fifth magnitude star marks the Water Jar asterism’s northernmost point. Pi Aquarii anchors the y-shaped configuration’s western branch. Pi Aquarii is the dimmest star in the Water Jar asterism. Pi Aquarii’s location north of the celestial equator qualifies its classification as a Northern Hemisphere star.

Pi Aquarii’s traditional name, Seat, has an uncertain origin. American astronomer and star lore enthusiast Richard Hinckley Allen (Aug. 4, 1838-Jan. 14, 1908) credits Dutch scholar Hugo Grotius (April 10, 1583-Aug. 28, 1645) with first usage of the traditional name.

Zeta Aquarii (ζ Aquarii; ζ Aqr) lies slightly southeast of Pi Aquarii. The fourth magnitude double star system marks the y-shaped asterism’s fork, where the tail divides into two branches. Zeta Aquarii shines as the asterism’s brightest star.

Zeta Aquarii’s traditional name is Sadaltager, or, alternatively, Altager. The traditional name derives from an Arabic phrase meaning “luck of the merchant” (Arabic: sa’d al-tjir). In 1895, English amateur astronomer Edward Ball Knobel (Oct. 21, 1841-July 25, 1930) reported the appearance of another traditional name in a 17th century star catalogue, al-Durrat al-muḍiyya fī al-ʻamāl al-shamsiyya (“Pearls of Brilliance Upon the Solar Operations”), by Muhammad al-Aksasi al-Muwaqqit, Egyptian astronomer and sheikh of Al-Azhar Mosque at Al-Azhar University in Cairo, Egypt. The al Achsasi catalogue identifies Zeta Aquarii as Akhir al Achbiya (“last of the tents”).

University of Illinois Emeritus Professor of Astronomy James B. “Jim” Kaler notes that Zeta Aquarii rates as a Northern Hemisphere, as of Nov. 21, 2003. The precessional cycle of approximately 26,000 years which changes the pole star and stellar positions is responsible for Zeta Aquarii’s transit across the celestial equator into the celestial northern hemisphere.

Eta Aquarii (η Aqr; η Aquarii) resides east of Zeta Aquarii. The fifth magnitude white subgiant-dwarf marks the y-shaped asterism’s eastern arm or branch. Eta Aquarii is the third brightest star in the Water Jar asterism.

American astronomer James B. “Jim” Kaler notes that Eta Aquarii is slated for precession-driven transit into the celestial northern hemisphere around Oct. 1, 2022.

The takeaway for the four star Water Jar asterism in Aquarius the Water Bearer is that the Southern Hemisphere constellation rises in the southwest in the late autumn skies of November in the Northern Hemisphere.

Water Jar asterism, in kite-shaped configuration with addition of Alpha Aquarii and deletion of Eta Aquarii, and other stars in Aquarius the Water Bearer constellation: International Astronomical Union and Sky & Telescope, CC BY 4.0 International, via International Astronomical Union (IAU)

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Water Jar asterism in Aquarius the Water Bearer constellation, depicted by Sidney Hall in Urania’s Mirror (1825), a set of 32 astronomical star chart cards: U.S. Library of Congress, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Sidney_Hall_-_Urania's_Mirror_-_Aquarius,_Piscis_Australis_&_Ballon_Aerostatique.jpg;
No known restrictions on publication in the U.S., via Library of Congress (LOC) Prints & Photographs Online Catalog (PPOC) @ https://www.loc.gov/pictures/item/2002695517/

Water Jar asterism, in kite-shaped configuration with addition of Alpha Aquarii and deletion of Eta Aquarii, and other stars in Aquarius the Water Bearer constellation: International Astronomical Union and Sky & Telescope, CC BY 4.0 International, via International Astronomical Union (IAU) @ https://www.iau.org/public/images/detail/aqr/; (contellation charts and tables main page URL) @ https://www.iau.org/public/themes/constellations/

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