Arcturus the Guardian

By Paul Curnow [B.ED]

One of the sparkling gems of the night sky is the star Arcturus (alpha Boötes). Arcturus is located in the constellation of Boötes ‘the Bear Herder’ and from classical depictions the star is situated near the foot of this heavenly herder. In classical mythology the constellation of Boötes depicts a “bear herder,” and is often associated with the northern constellation Ursa Major “The Great Bear.”

Boötes is an ancient constellation and in addition to being depicted as driving a bear through the sky, he is often depicted holding the lead of two hunting dogs, the constellation Canes Venatici. In classical mythology Boötes represents Arcas, who is the son of the Olympian Zeus ‘King of gods’ and whose mother was Callisto the daughter of King Lycaon of Arcadia. Zeus had to hide his son Arcas from his jealous wife the goddess Hera. Earlier, the goddess Hera in anger had changed Callisto the mother of Arcas into a bear. Eventually, Arcas would become the king of Arcadia, a region in Greece, which had been named in his honour. Consequently, Arcas became a great hunter and one day while out hunting in the forest he came across his mother. After not seeing her son for so long, she went forth to give him a hug. Arcas, not realising that the bear was his mother swiftly shot and killed her with an arrow. Taking pity on Callisto and his son, Zeus elevated them both into the sky appearing as the large and small bear (Ursa Major & Ursa Minor).

The name Arcturus (alpha Boötes) comes from the ancient Greek Αρκτούρος and means “the Bear Guardian, or Watcher,” referring to its association with the constellation of Ursa Major. It appears to be first mentioned in Homer’s Odyssey and was also mentioned by Hesiod and Ptolemy. In Arabic it has been known by a number of different names such as, Al-Simāk al-Rāmih meaning, "leg of the lance-bearer" or Al-Hāris al-Samā meaning, "the keeper of heaven.” In addition, early Chaldean astronomers knew it as Papsukal, “the guardian messenger.”

Arcturus is the brightest star in the northern sky. It is an orange giant star located approximately 37 light years (or 11.3 parsecs) from our sun and has an apparent magnitude of -0.05. Arcturus is believed to be 115 times as luminous as our sun, but a low-density star of only around 4 solar masses. In fact over the next five billion years it is believed our sun will swell up to become a star somewhat similar to Arcturus. Additionally, not including the star Rigel Kentaurus (alpha Centauri) - Arcturus has the largest proper motion of first magnitude stars observed from Earth. Sir Edmond Halley (1656-1742) the renowned English astronomer first detected this movement in 1718. Interestingly, because of this motion Arcturus is now the closest to the sun it will ever be - as it heads towards Virgo and slowly fades from view over the next half a million years.

In addition, one of the most interesting pieces of trivia regarding Arcturus is that the light coming from it was used to open a world fair, Chicago’s “Century of Progress” Exposition in 1933. The light from Arcturus was focused using telescopes on to photoelectric cells, which in turn generated the power to trigger a switch that would turn on the floodlights of the exposition ground. At the time it was believed Arcturus was 40 light years away which meant that the light leaving the star would have left there in 1893, the same time that another fair had been held in Chicago. However, this later be proved to be in error by a few light years.

The Boorong Aboriginal People who once lived around Lake Tyrrell (pictured left) in north-western Victoria knew the star Arcturus as Marpeankurrk. In the Dreaming of the Boorong People, they believed that Marpeankurrk was the first to discover the larvae of the white ant/termite. Furthermore, the Boorong called the larvae ‘bittur’ and they believed that Marpeankurrk had taught their ancestors how to find it. Therefore, Arcturus or Marpeankurrk was of prime importance to early Australians as a guide to the seasonal availability of the larvae of the white ant/termite, which was a regular source of food and protein that aided their survival in an arid environment.

In addition, Polynesian navigators knew Arcturus as Hokule'a, meaning the "Star of Joy,” and for Hawaiians the star appears at their zenith. The Lakota Sioux Peoples of North America called the star Itkob u which when translated means “going towards,” and the Inuit Peoples of the north called Arcturus Uttuqalualuk, “the old man.” In ancient China, it was known as Ta Kiō, “the Great Horn.” The Kobeau Indian People of northern Brazil see Boötes as a Piranha, with Arcturus marking the centre point of the tail of the fish. Also, the Aboriginal People who come from Millingimbi in the Northern Territory identify the star as a man in the sky.

The name ‘Arcturus’ also features in popular culture. For example, the science fiction author David Lindsay wrote, A Voyage to Arcturus, which was published in 1920. In addition, in the popular television series Star Trek: The Next Generation ‘Arcturus IV’ is a planet, home world of the Arcturian people. The ‘Arcturian’ species are a militaristic race that reproduces by cloning. They even have a popular drink known as the ‘Arcturian Fizz’! Furthermore in the video game Weird Worlds: Return to Infinite Space, there is a character named ‘Prince Arcturus’. Therefore, not only does Arcturus inspire the scientific world but the name also grabs the attention of the science fiction world. Adelaide even has an avenue named after this stellar guardian in the southern suburb of Huntfield Heights.

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Updated 6th of August 2011