Taurus the Bull

Taurus the Bull
Taurus represented in the celestial card set published in 1824, called Urania's Mirror. Illustrations are based on Alexander Jamieson's atlas.

Taurus is an ancient constellation, included in Ptolemy's Almagest in the 2nd century AD. However, it had been a Sumerian constellation long before that. In the epic tale of Gilgamesh, the Bull of Heaven (Taurus) was sent to kill Gilgamesh (Orion) for rejecting the goddess Ishtar. The outcome was that the Sumerian hero Gilgamesh prevailed, perhaps leaving the bull's red eye – the star Aldebaran – glaring at Orion.

The stories of the constellations have changed often over several thousand years. In the best known classical tales Orion doesn't feature. The bull is the guise adopted by Zeus for the seduction of princess Europa. As a beautiful and friendly white bull, he so delighted Europa that she draped him with flowers and climbed on his back. It would have been quite a surprise when he swam out to sea and carried her away.

The bull's eye Aldebaran (al-DEB-uh-run), also known as Alpha Tauri, is the brightest star of Taurus. It's an aging orange giant 65 light years away, over 50 times bigger across and over 400 times brighter than the Sun. If Aldebaran were where our Sun is, it would fill the space out to the orbit of Mercury.

Beta Tauri (Elnath or Alnath) is the constellation's second brightest star, a white giant that marks one of the bull's horns. Although it's more than 700 times brighter than the Sun, it doesn't seem as bright as Aldebaran because it's twice as far away. It used to be known also as Gamma Aurigae, representing the charioteer Auriga's foot. When the modern constellations were officially defined, the constellation boundaries were uniquely defined. This left the bull with his horn, but the charioteer lost a foot.

The variable star Lambda Tauri, which is 480 light years away, is a triple star system. The main reason for its variability is that two of the three stars form an eclipsing binary. The binary is almost edge on, so as the stars circle each other about every four days, we see them taking turns to block each other's light from us. Lambda Tauri A is nearly six thousand times brighter than the Sun and its companion over a hundred times as luminous as the Sun. The third star, Lambda Tauri C, is smaller than the Sun and orbits the binary every 33 days.

Star clusters
Taurus contains two prominent star clusters that can be seen with the unaided eye: the Hyades and the Pleiades.

Aldebaran looks as though it's a member of the Hyades, but it just happens to be in the same line of sight. The Hyades cluster is over twice as far away as Aldebaran. It's an open star cluster of several hundred members and some of the bright stars make up the V-shape of the bull's head. In Greek mythology the Hyades were rain nymphs, daughters of Atlas, the Titan who held up the world. In the myths, the number of sisters and their names vary between sources. And unlike those representing their half sisters the Pleiades, the bright stars of the Hyades aren't named.

The Pleiades are probably the best known star cluster. They're the daughters of Atlas and an oceanic nymph. In English they're commonly known as the Seven Sisters. Although there are supposed to be seven of them, it's difficult to see more than six without binoculars. Many cultures represent the Pleiades with six stars and there are myths about a missing Pleiad. We only see the brightest of the cluster's stars which number at least a thousand.

The Crystal Ball Nebula (NGC 1514) is a planetary nebula discovered by William Herschel in 1790. He saw what looked like a bright central star surrounded by some nebulous material. Some nebulae of this type looked like planets in 18th century telescopes. However these nebulae are formed from the material of the outer layers of a dying sunlike star. [Image: Göran Nilsson & The Liverpool Telescope]

The most spectacular object in Taurus is the Crab nebula. It was discovered in 1731, though the event that created it had been seen nearly seven hundred years before by Chinese observers. It's a supernova remnant containing a pulsar, which is a spinning neutron star. It's what is left of the core of a massive star following the collapse and convulsive explosion in which it blew off its outer layers. The gas cloud is now twelve light years across – that's about 120 trillion kilometers or 72 trillion miles – and still expanding.

You Should Also Read:
Pleiades - the Seven Sisters
M1 Crab Nebula
What Is a Nebula

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