Taurus (constellation)

Taurus is one of the constellations of the zodiac. Its name is a Latin word meaning 'bull', and its astrological symbol is a stylized bull's head: (Unicode ♉). Taurus is a large and prominent constellation in the northern hemisphere's winter sky, between Aries to the west and Gemini to the east; to the north lie Perseus and Auriga, to the southeast Orion, to the south Eridanus, and to the southwest Cetus.

The recommended three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'Tau'.^[2] The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 26 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 03^h 23.4^m and 05^h 53.3^m, while the declination coordinates are between 31.10° and -1.35°.^[4]

Notable features

In September and October, Taurus is visible in the evening along the eastern horizon. The most favorable time to observe Taurus in the night sky is during the months of December and January. By March and April, the constellation will appear to the west during the evening twilight.^[6] During November, the Taurid meteor shower appears to radiate from the general direction of this constellation. The Beta Taurid meteor shower occurs during the months of June and July in the daytime, and is normally observed using radio techniques.^[7]

The brightest member of this constellation is Aldebaran, an orange-hued, spectral class K5 III giant star.^[8] Its name is from الدبران al-dabarān, Arabic for 'the follower' (of the Pleiades).^[9][10] Forming the profile of a Bull's face is a V or A-shaped asterism of stars. This outline is created by prominent members of the Hyades,^[11] the nearest distinct open star cluster after the Ursa Major Moving Group.^[12] In this profile, Aldebaran forms the bull's bloodshot eye, which has been described as "glaring menacingly at the hunter Orion",^[13] a constellation that lies just to the southwest. The Hyades span about 5° of the sky, so that they can only be viewed in their entirety with binoculars or the unaided eye.^[14]

In the northeastern quadrant of the Taurus constellation lie the Pleiades, one of the best known open clusters, easily visible to the naked eye. The seven most prominent stars in this cluster are at least visual magnitude six, and so the cluster is also named the "Seven Sisters". However, many more stars are visible with even a modest telescope.^[15] The name of the star Aldebaran most likely comes from the fact that it follows the Pleiades during the nightly motion of the celestial sphere across the sky.^[9]

To the west, the two horns of the bull are formed by Beta (β) Tauri and Zeta (ζ) Tauri; two star systems that are separated by 8°. Beta is a white, spectral class B7 III giant star known as El Nath, which comes from the Arabic phrase "the butting", as in butting by the horns of the bull. It is the second brightest star in the constellation, and shares the border with the neighboring constellation of Auriga. Zeta Tauri is an eclipsing binary star that completes an orbit every 133 days.^[8]

A degree to the northwest of ζ Tau is the Crab Nebula (M1), a supernova remnant. This expanding nebula was created by a Type II supernova explosion, which was seen from Earth on July 4, 1054. It was bright enough to be observed during the day, and is mentioned in Chinese historical texts. At its peak the supernova reached magnitude −4, but the nebula is currently magnitude 8.4 and requires a telescope to observe.^[16][17]

The star Lambda (λ) Tauri is an eclipsing binary star. This system consists of a spectral class B3 star being orbited by a less massive class A4 star. The plane of their orbit lies almost along the line of sight to the Earth. Every 3.953 days the system decreases in brightness by 1.1 magnitudes as the brighter star is partially eclipsed by the dimmer star. The two stars are separated by only 0.1 astronomical units, so their shapes are modified by tidal interaction. This results in a variation of their net magnitude throughout each orbit.^[18]

Located about 1.8° west of Epsilon (ε) Tauri is T Tauri, the prototype of a class of variable stars called T Tauri stars. This star undergoes erratic changes in luminosity, varying between magnitude 9 to 13 over a period of weeks or months.^[19] This is a newly formed stellar object that is just emerging from its envelope of gas and dust, but has not yet become a main sequence star.^[20] The surrounding reflection nebula NGC 1555 is illuminated by T Tauri, and thus is also variable in luminosity.^[21]

This constellation includes part of the Taurus-Auriga complex, a star forming region of sparse, filamentary clouds. This spans a diameter of 30 parsecs and contains 3.5 × 10⁴ solar masses of material, which is both larger and less massive than the Orion Nebula.^[22] At a distance of 150 parsecs, this is one of the nearest active star forming regions.^[23]

History and mythology

The identification of the constellation of Taurus with a bull is very old, certainly dating to the Chalcolithic, and perhaps even to the Upper Paleolithic. Michael Rappenglück of the University of Munich believes that Taurus is represented in a cave painting at the Hall of the Bulls in the caves at Lascaux (dated to roughly 15,000 BCE), which he believes is accompanied by a depiction of the Pleiades.^[24][25]

Taurus marked the point of vernal equinox in the Chalcolithic and the Early Bronze Age (the "Age of Taurus"), from about 4000 BCE to 1700 BCE.^[26] The Pleiades were closest to the Sun at vernal equinox around the 23rd century BC. In Babylonian astronomy, the constellation was listed in the MUL.APIN as GU₄.AN.NA, "The Heavenly Bull".^[27] As this constellation marked the vernal equinox, it was also the first constellation in the Babylonian zodiac and they described it as "The Bull in Front".^[28] The Akkadian name was Alu.^[29]

In the Mesopotamian Epic of Gilgamesh, one of the earliest works of literature, the goddess Ishtar sends Taurus, the Bull of Heaven, to kill Gilgamesh for spurning her advances.^[30] In early Mesopotamian art, the Bull of Heaven was closely associated with Inanna, the Sumerian goddess of sexual love, fertility, and warfare. One of the oldest depictions shows the bull standing before the goddess' standard, as it has 3 stars depicted on its back (the cunieform sign for 'star-constellation') there is good reason to regard this as the constellation later known as Taurus.^[29]

The same iconic representation of the Heavenly Bull was depicted in the Dendera zodiac, an Egyptian bas-relief carving in a ceiling that depicted the celestial hemisphere using a planisphere. In these ancient cultures, the orientation of the horns was portrayed as upward or backward. This differed from the later Greek depiction where the horns pointed forward.^[31] To the Egyptians, the constellation Taurus was a sacred bull that was associated with the renewal of life in spring. About 4,000 years ago, the spring equinox entered Taurus. The constellation would become covered by the Sun in the western sky as spring began. This 'sacrifice' led to the renewal of the land.^[32] To the early Hebrews, Taurus was the first constellation in their zodiac and consequently it was represented by the first letter in their alphabet, Aleph.^[33]

In Greek mythology, Taurus was identified with Zeus, who assumed the form of a magnificent white bull to abduct Europa, a legendary Phoenician princess. In illustrations, only the front portion of this constellation are depicted; in Greek mythology this was sometimes explained as Taurus being partly submerged as he carried Europa out to sea.^[34] Greek mythographer Acusilaus marks the bull Taurus as the same that formed the myth of the Cretan Bull, one of The Twelve Labors of Heracles.^[35]

Taurus became an important object of worship among the Druids. Their Tauric religious festival was held while the Sun passed through the constellation.^[26] In Buddhism, legends hold that Gautama Buddha was born when the Full Moon was in Vaisakha, or Taurus.^[36] Buddha's birthday is celebrated with the Wesak Festival, or Vesākha, which occurs on the first or second Full Moon when the Sun is in Taurus. This date was formalized at the first Conference of the World Fellowship of Buddhists in 1950.^[37]

Astrology

As of 2008^[update], the Sun appears in the constellation Taurus from May 13 to June 21.^[38] In tropical astrology, the Sun is considered to be in the sign Taurus from April 21 to May 20.^[39]

Notes

References

Further reading

• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.

External links

• The Deep Photographic Guide to the Constellations: Taurus
• BBC article on the possibility of Taurus being represented in Lascaux
• Star Tales – Taurus

Coordinates: 04^h 00^m 00^s, +15° 00′ 00″