Taurus - The Bull

Taurus is a prominent winter constellation located between Aries and Gemini. To find Taurus, follow the line of stars in Orion's belt upward until you reach the red star Aldebaran. Look for the V-shaped cluster known as the Hyades, which marks the head of the bull. Taurus is best seen from November to February.

History and Mythology

Taurus is probably one of the earliest constellations to be named. Since the beginning of civilization, it has been associated with the bull's attributes of strength and fertility. The bull was sacred to the Egyptians and given a place of honor in ceremonies and religions.

Two Greek myths are associated with Taurus. The first says that Taurus was the snow-white bull which carried away Europa, only to be revealed as Zeus. The second legend tells of Orion the hunter. He pursued the seven daughters of Atlas, and they were changed into doves and escaped into the sky. The seven daughters are represented by the Pleiades star cluster.

Notable Stars

The magnificent red giant star Alpha Tauri, or Aldebaran, marks the eye of Taurus, the bull. Its name in Arabic means "follower", because it follows the Pleiades. At magnitude 0.9, Aldebaran is the 13th brightest star in the sky. It is about 65 light years away, and has a faint red dwarf companion that is only visible in large telescopes. While Aldebaran appears to be part of the Hyades star cluster, it is only a foreground object, at about half the cluster's distance. Aldebaran is mildly variable, changing irregularly in brightness by about 0.2 magnitudes.

Elnath, at magnitude 1.7, is the second-brightest star in Taurus. It was once considered to be part of two constellations, and carries both the designations Beta Tauri and Gamma Aurigae. Since El Nath now lies within the formal boundaries of Taurus, the latter designation is rarely used. Physically, El Nath is a hot blue giant star 130 light years away, with a luminosity 700 times the Sun's.

Clusters, Nebulae, and Galaxies

The Hyades are the nearest open star cluster to our solar system. They are a group of cool, red stars about 130 light-years away. In mythology the Hyades were half sisters of the Pleiades, and their parents were Atlas and Aethra. The Hyades contains many stars which have evolved for a period of perhaps 400 million years. The Hyades share the same age and motion through space as another well-known open cluster, the Beehive (M 44) in Cancer, and thus they probably formed together, even though they now appear in very different parts of the sky.

But the most famous star cluster in Taurus, if not the entire sky, is the Pleiades (M 45). The Pleiades mark the shoulder of Taurus; the names of its brightest stars are Alcyone, Merope, Celaeno, Taygeta, Sterope, Electra and Maia. These stars are known as the Seven Sisters, the daughters of Atlas. Under very good conditions, the naked eye can count up to a dozen Pleiads; binoculars reveal up to 100; the cluster may contain up to 500 stars in total.

Large telescopes reveal swirls of bluish reflection nebulosity surrounding the brighter stars; this nebulosity appears to be unrelated to the cluster, and is simply starlight reflected off a cloud of interstellar dust which it happens to be passing through. The Pleiades are a very young cluster, less than 100 million years old. Its brightest members are all hot, blue, fast-rotating giant stars with hundreds of times the Sun's luminosity. The Pleiades are one of the nearest clusters, about 440 light years away.

Northeast of the Hyades, near the bull's right horn, lies M 1, the famous Crab Nebula. It was produced by a supernova which occurred in the year 1054. It is expanding into interstellar space at thousands of kilometers per second, and is now nearly 10 light-years across. Since Crab Nebula is 6,300 light years away, this titanic explosion actually took place 5,000 years ago.

At the center of the Crab Nebula is a neutron star which rotates about 30 times per second. The neutron star is the remnant of the collapsed star which produced the supernova explosion. It contains the mass of the Sun, but it measures only a few dozen miles in diameter. As it collapsed, its rotation rate increased rapidly, just like an ice skater who brings her arms inward as she spins. Hot spots on the neutron star's surface produce pulses of X-ray and radio waves as they spin in about out of view; this object was one of the first pulsars ever discovered.

Often overlooked in favor of the Pleiades and Hyades are the open star clusters NGC 1746 and NGC 1647. Both of these 6th-magnitude open clusters are good binocular objects, lying at distances of 1500 and 1800 light years, respectively.

For larger telescopes, NGC 1555 is a reflection nebula located in the constellation Taurus, near the famous variable star T Tauri. It is also called Hind's Variable Nebula. T Tauri, the variable star embedded in dust and gas at the center of NGC 1555, is the prototype for a class of very young stars that have just recently emerged from the dense dust and gas "cocoons" in which they formed.

Apparently this was an easier object to view in the mid 1800's; it is currently a very tough visual target. Nebulosity around a nearby 14th magnitude star was cataloged as NGC 1554. But current photographs show nothing at this position; hence NGC 1554 is known as Struve's Lost Nebula.

NGC 1514 is a very dim planetary nebula, and another challenging object for larger telescopes.