Earth and Space News: Winter Hexagon asterism

Showing posts with label Winter Hexagon asterism. Show all posts

Wednesday, March 25, 2020

Heavenly G Asterism Indents Rather Than Encircles Betelgeuse

Summary: The Heavenly G asterism indents rather than encircles Betelgeuse in a refashioning of the Winter Hexagon asterism.

Betelgeuse in Orion the Hunter constellation holds the place of honor in the Heavenly G asterism as the celestial letter’s final lobe; nebulas of the Orion Molecular Cloud complex surround Constellation Orion with Heavenly G participants’ red Betelgeuse (upper left) and bluish-white Rigel (lower right); Thursday, Aug. 23, 2012: Rogelio Bernal Andreo, CC BY SA 3.0 Unported, via Wikimedia Commons

The Heavenly G asterism indents rather than encircles Betelgeuse as the celestial letter refashions the Winter Hexagon asterism.

Canadian comet and minor planet discoverer David H. Levy (born May 22, 1948) describes the Heavenly G asterism in his bestselling guide to the night sky, Skywatching (1994). In his highlights of Sky Chart 1, “Northern Latitudes Looking South,” Levy exemplifies March and April’s interesting bright star patterns with the Heavenly G.

Levy’s description units seven stars from five constellations. He begins the asterism at red Aldebaran (α Tauri, Alpha Tauri; α Tau, Alpha Tau) in Taurus the Bull constellation. His tracing continues to sextuple star system Castor (α Geminorum, Alpha Geminorum; α Gem, Alpha Gem) and orange-hued Pollux (β Geminorum, Beta Geminorum; β Gem, Beta Gem) in Gemini the Twins constellation. The asterism swings to white-hued binary star Procyon (α Canis Minoris, Alpha Canis Minoris; α CMi, Alpha CMi) in Canis Minor the Lesser Dog constellation and then catches white to blue-white binary star Sirius (α Canis Majoris, Alpha Canis Majoris; α CMa, Alpha CMa) in Canis Major the Greater Dog constellation. The asterism then rounds to blue-white multiple star system Rigel (β Orionis, Beta Orionis; β Ori, Beta Ori) in Orion the Hunter constellation. The starry G takes shape with a brake at Rigel to indent within Orion for the asterism’s final point, red Betelgeuse (α Orionis, Alpha Orionis; α Ori, Alpha Ori).

American physicist David L. Huestis of Skyscrapers Inc. Amateur Astronomical Society of Rhode Island, the United Kingdom-based Society for Popular Astronomy (SPA) and Whitby & District Astronomical Society in North Yorkshire, North East England, shape the Heavenly G with eight stars from six constellations. This version of the asterism begins with golden quadruple star system Capella (α Aurigae, Alpha Aurigae; α Aur, Alpha Aur) in Auriga the Charioteer constellation. This variation agrees with Levy’s next five stars as Gemini’s Castor and Pollux, Canis Major’s Procyon, Canis Major’s Sirius and Orion’s Rigel curve the celestial letter. Rather than braking at Rigel, however, this form of the asterism continues to Taurus the Bull’s Aldebaran, which was the starting point for Levy’s Heavenly G. The indent from Aldebaran back to Orion’s Betelgeuse completes the asterism.

Christine Kronberg’s Table of Asterisms on her USM (Universitäts-Sternwarte München; University Observatory Munich)- and LRZ (Leibniz-Rechenzentrum; Leibniz Supercomputing Centre)-sponsored site, The Munich Astro Archive (MAA), identifies nine stars in six constellations for the G-shaped asterism. Her Heavenly G agrees with Levy’s version by starting with Aldebaran in Taurus. Kronberg agrees with Skyscrapers Inc. and Whitby & District astronomical societies and the Society for Popular Astronomy by including Auriga’s Capella. Kronberg’s asterism then follows the usual trek through Castor and Pollux, Procyon, Sirius and Rigel. Her G, however, injects a new player into the asterism by shooting from Rigel to bluish-white Bellatrix (γ Orionis, Gamma Orionis; γ Ori, Gamma Ori), which sits in the opposite shoulder from Betelgeuse. The indent for Betelgeuse occurs at Bellatrix.

In his Sky & Telescope article for Jan. 13, 2016, American amateur astronomer Robert P. “Bob” King notes that refashioning the Winter Hexagon into the Heavenly G allows Betelgeuse, excluded from the Hexagon’s “geometric merrymaking,” to achieve inclusion “in the Heavenly G, completing the letter’s inner lobe.” King’s variant of the Heavenly G names eight stars in six constellations. King’s Heavenly G agrees with Kronberg’s version for the first seven named stars, Aldebaran through Rigel. King’s G, however, shoots from Rigel to an unnamed star in Orion’s bow before indenting for Betelgeuse.

Bob “Astrobob” King notes that the Winter Hexagon morphs into the Winter Heptagon with the addition of a seventh star, Castor, to the Hexagon’s grouping of Aldebaran, Capella, Pollux, Procyon, Sirius and Rigel. The Winter Hexagon and the Winter Heptagon are also known as the Winter Circle. In their home telescope guide to the night sky, Turn Left at Orion (2011), American research astronomer Guy Consolmagno and geophysicist Daniel M. “Dan” Davis identify the bright encircling of Betelgeuse as a January to March sky guidepost. First magnitude stars Sirius, Rigel, Procyon, Aldebaran and Pollux and second magnitude star Castor “make a ring” around first magnitude star Betelgeuse.

The takeaway for the Heavenly G asterism that indents rather than encircles Betelgeuse are that four versions of the starry letter gather together a range of seven to nine stars in five to six constellations and that the G-shaped asterism refashions the Winter Circle or Winter Hexagon asterisms by including Orion’s red Betelgeuse.

Acknowledgment

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

Image credits:

one of at least four known versions of the Heavenly G asterism; all versions include Aldebaran, Betelgeuse, Castor and Pollux, Procyon, Rigel and Sirius: Young Stargazers @YoungStargazers, via Twitter March 2, 2019, @ https://twitter.com/YoungStargazers/status/1101903919821803521

For further information:

Consolmagno, Guy; and Dan M. Davis. Turn Left at Orion. Fourth edition. Cambridge UK; New York NY: Cambridge University Press, 2011.

Dawson, Mark. “The Heavenly ‘G.’” Whitby & District Astronomical Society > In-Focus. Jan. 31, 2015.
Available @ http://whitby-astronomers.com/focus/heavenly-g

Huestis, Dave. “Observing the Winter Circle.” Skyscrapers Inc. February 2015.
Available @ http://www.theskyscrapers.org/observing-the-winter-circle

King, Bob. “Asterisms for Winter Nights.” Sky & Telescope > Observing. Jan. 13, 2016.
Available @ https://www.skyandtelescope.com/observing/winter-sky-asterisms011320161301/

King, Bob. Night Sky With the Naked Eye: How to Find Planets, Constellations, Satellites and Other Night Sky Wonders Without a Telescope. Salem MA: Page Street Publishing Co., 2016.

Kronberg, Christine. Heavenly G.” the Munich Archive Astromaps > Constellations > Asterisms > Table of Asterisms.
Available @ http://maps.seds.org/Const/asterism.html

Levy, David H. Skywatching. Revised edition. San Francisco CA: Fog City Press, 2007.

Marriner, Derdriu. “Winter Hexagon Asterism Gathers Six Stars From Six Constellations.” Earth and Space News. Wednesday, Jan. 4, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/01/winter-hexagon-asterism-gathers-six.html

Marriner, Derdriu. “Winter Triangle Is Asterism Within Winter Hexagon Asterism.” Earth and Space News. Wednesday, Jan. 11, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/01/winter-triangle-is-asterism-within.html

McClure, Bruce. “See the Winter Circle, or Hexagon.” EarthSky > Favorite Star Patterns. Jan. 12, 2019.
Available @ https://earthsky.org/favorite-star-patterns/winter-circle-highlights-brightest-winter-stars

Young Stargazers ‏@YoungStargazers. “Early March evenings start with the main winter constellations dominating the southern sky. Their brightest stars form an asterism known as the "Heavenly G" (1/3).” Twitter. March 2, 2019.
Available @ https://twitter.com/YoungStargazers/status/1101903919821803521

Wednesday, January 4, 2017

Winter Hexagon Asterism Gathers Six Stars From Six Constellations

Summary: The Winter Hexagon asterism gathers six stars from six constellations for its prominent sky appearances from December to February.

asterism within an asterism: Winter Hexagon with Winter Triangle: Jim Thomas (Jomegat), Public Domain, via Wikimedia Commons

Also known as the Winter Circle or Winter Oval, the Northern Hemisphere's Winter Hexagon asterism gathers six stars from six constellations and also features an asterism within an asterism, the smaller Winter Triangle asterism, for its prominent sky appearances from December to February.

The six borrowed stars form a stellar hexagon that links them, outside of their individual constellations, in a recognizable pattern of stars known as an asterism. The six vertices, or angled meeting points of the imaginary hexagon’s six sides, are held by Auriga the Charioteer’s Capella, Taurus the Bull’s Aldebaran, Orion the Huntsman’s Rigel, Canis Major’s Sirius, Canis Minor’s Procyon and Gemini the Twins' Pollux.

In northern latitudes, the Winter Hexagon rises in the south. In December, the hexagonal asterism is high in the sky after midnight. Early January welcomes the Winter Hexagon’s highest point at around 11 p.m. In mid-February, the hexagon reaches its highest point around 8 or 9 p.m.

The Winter Hexagon is known as the Summer Hexagon or the Summer Circle in the Southern Hemisphere. English astronomer David Darling suggests extending the asterism southward, in the northern tropics and in the Southern Hemisphere, to include Canopus, the second brightest star in the southern constellation of Carina the Ship’s Keel.

Including Canopus, the second brightest star, after Sirius, in Earth’s night skies, would transform the Summer Hexagon into the Summer Heptagon, a seven-sided asterism. Amateur astronomer and Sky & Telescope contributor Bob King suggests a variant Winter/Summer Heptagon by adding Gemini’s Castor to the Winter Hexagon’s traditional sextet.

The Winter Hexagon asterism claims further structural interest for fueling the imaginations of stargazers. The hexagonal asterism contains another asterism within its asterismal boundaries by way of the Winter Triangle asterism. The Winter Triangle is an equilateral triangle that shares two vertices, Procyon and Sirius, with the Winter Hexagon. Orion’s Betelgeuse, located off-center inside the Winter Hexagon, tops the Winter Triangle.

High ranking brightness of all six stars explains the dramatic visibility of the Winter Hexagon asterism. All six appear in the list of 17 brightest stars in Earth’s night skies. Of those six, four (Sirius, Capella, Rigel, Procyon) are in the top eight.

Within the Northern Hemisphere’s brightest night stars, all six appear in the top 12 list. All except Pollux are in the top nine. The quartet of Sirius, Capella, Rigel and Procyon number in the Northern Hemisphere’s top six brightest night stars.

The Winter Hexagon is easy to locate because of its association with Orion. The Winter Hexagon encloses Orion and claims the constellation’s second brightest star, Rigel, as a hexagonal vertex. Rigel marks the constellation’s southwestern corner and the hexagon’s southwestern point.

The constellation of Greek mythology’s giant hunter dominates the sky as one of the night’s most conspicuous and most easily recognizable constellations. Orion’s brightest star, red supergiant Betelgeuse, marks the hunter’s right shoulder in front-facing depictions and his left shoulder in back-view illustrations. Rigel represents Orion’s left foot in front views and right foot in back views.

The Winter Hexagon is a showy asterism that shines on its own merits but also increases viewer interest with the dream catching possibilities of celestial bodies framed within the hexagon’s borders. Through its reliance upon Rigel, the Winter Hexagon always frames the recognizable magnificence of Orion the Hunter.

Apart from Orion’s constancy, other bright visitors also find themselves inside the Winter Hexagon. Amateur astronomer Bob King, known popularly as Astro Bob, noted the Winter Hexagon’s trapping of the waxing gibbous moon Saturday, Jan. 7, 2012, and Wednesday evening, Jan. 20, 2016. On Thursday, Jan. 9, 2014, Astro Bob shared Jupiter’s confinement within the Winter Hexagon.

The takeaway for the Winter Hexagon asterism is its wintry brightness as it brings together six bright stars from six familiar constellations for easy visibility from December to February.

Southern Hemisphere’s Summer Hexagon, visited by Jupiter; Winter Hexagon over Gensan, southern Philippines, Monday, Dec. 2, 2013, 22:27:28: peter jones (peterjonesdelacruz27), CC BY ND 2.0 Generic, via Flickr

Acknowledgment

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

Image credits:

Winter Hexagon with Winter Triangle: Jim Thomas (Jomegat), Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Wintersky.jpg

Astro Bob (Bob King). “Looking for Aurora Tonight? Check Out the Winter Hexagon + 2.” AreaVoices > Archives > January 2014. Jan. 9, 2014.
Available @ http://astrobob.areavoices.com/2014/01/09/looking-for-aurora-tonight-check-out-the-winter-hexagon-2/

Astro Bob (Bob King). “Moon and Winter Hexagon Bright on Bright Tonight.” AreaVoices > Archives > Jan. 7, 2012.
Available @ http://astrobob.areavoices.com/2012/01/07/moon-and-winter-hexagon-bright-on-bright-tonight/

Astro Bob (Bob King). “What Would It Look Like if Mars, Saturn or Neptune Replaced the Moon?” AreaVoices > Archives > February 2015.
Available @ http://astrobob.areavoices.com/2015/02/01/what-would-it-look-like-if-mars-saturn-or-neptune-replaced-the-moon/

Astro Bob (Bob King). “Wolf Moon Trapped by the Winter Hexagon.” AreaVoices > Archives > January 2016.
Available @ http://astrobob.areavoices.com/2016/01/19/wolf-moon-trapped-by-the-winter-hexagon/

Astro Bob (Bob King). “You Absolutely Must See the Winter Hexagon Tonight.” AreaVoices > Archives > January 2013.
Available @ http://astrobob.areavoices.com/2013/01/17/you-must-absolutely-see-the-winter-hexagon-tonight/

Constellation Guide Admin. “Winter Hexagon.” Constellation Guide. March 13, 2016.
Available @ http://www.constellation-guide.com/winter-hexagon/

Darling, David. “Winter Hexagon.” The Worlds of David Darling > Encyclopedia of Science.

Available @ http://www.daviddarling.info/encyclopedia/W/Winter_Hexagon.html

Hufnagel, Beth; Bob Stein. “16 Brightest Stars (Visible in the Northern Hemisphere).” Michigan State University Department of Physics and Astronomy > Courses > 1997 Spring.
Available @ https://www.pa.msu.edu/courses/1997spring/ISP205/sec-3/brightstars.html

McClure, Bruce. “Winter Circle: Brightest Winter Stars.” EarthSky> Favorite Star Patterns > Science Wire. Jan. 10, 2016.
Available @ http://earthsky.org/favorite-star-patterns/winter-circle-highlights-brightest-winter-stars

Millás, Isolina V. “The Brightest Stars of the Southern Hemisphere.” Popular Astronomy, vol. 26 (June-July 1918): 387-391.
Available via Harvard ADSABS (NASA Astrophysics Data System Abstracts) @ http://articles.adsabs.harvard.edu//full/1918PA.....26..387M/0000387.000.html

Ridpath, Ian. “The 25 Brightest Stars as Seen From Earth.” Ian Ridpath.
Available @ http://www.ianridpath.com/brightest.htm

Staal, Julius D.W. The New Patterns in the Sky: Myths and Legends of the Stars. Blacksburg VA: McDonald and Woodward Publishing Co., 1988.

“Winter Hexagon Over Stagecoach Colorado.” NASA’s Astronomy Picture of the Day (APOD).
Available @ http://apod.nasa.gov/apod/ap110103.html