Among the many fascinating constellations visible in the skies of the Southern Hemisphere is Dorado, the Goldfish or Dolphinfish. This constellation, and the stars and other objects within it, was named and catalogued in a famous star atlas called "Uranometria," published by German astronomer Johann Bayer in 1603. Bayer named the configuration after hearing reports of this part of the sky by explorers of the Southern Hemisphere.
Dorado, made up of faint, unnamed stars, is dominated by a bright, hazy galaxy called the Large Magellanic Cloud (introduced in last week's Sky Guide). Within the Large Magellanic Cloud is a large nebula (a cloud of gases and dust) commonly called the Tarantula Nebula for its supposed resemblance to a spider. Other names include the Loop Nebula and the True Lovers' Knot, and it's bigger and brighter than any nebula known in our galaxy and perhaps the universe. If it were as close to Earth as the Orion Nebula (1,500 light-years away), it would cover an area sixty times the apparent diameter of the sun and appear thirty times brighter than Sirius, the brightest star in the sky.
At its distance of about 170,000 light-years, however, the Tarantula Nebula looks to the naked eye like a fuzzy star. But don't be fooled: the deceptively calm-looking smudge of light harbors an exorbitantly active stellar nursery, where stars of enormous energy and luminosity are bursting into life. Armed with images sent by the Hubble Space Telescope, astronomers study this fascinating nebula for information on how stars form and how so many extremely powerful stars--of a type once considered highly rare--can have formed in one place.
Planets of the Week
Mars is above the western horizon in the evening hours, setting at about 10:00 p.m. High in the sky at sunset, Saturn shines against the glittering backdrop of the constellation Taurus. Jupiter appears eastward of Saturn it in the constellation Gemini and is the brightest object in the sky these nights, after the moon.
At 9:00 p.m. on January evenings the last of the late-summer and fall constellations are just about to set. Deneb, the bright alpha star in the constellation Cygnus, is just above the northwestern horizon. The Great Square of Pegasus is almost due west, and the constellations Cepheus, Cassiopeia, Perseus, and Andromeda, somewhat higher, are still visible. Ursa Minor, also known as the Little Bear or the Little Dipper, hangs almost straight down from Polaris, the North Star.
Leo, the Lion, and its bright alpha star Regulus are just rising in the east-northeast. Between Leo and Gemini lies the faint zodiacal constellation Cancer, the Crab. To the north is Ursa Major, the Great Bear. The Big Dipper, a part of that large constellation, stands upright on its handle.
The southeastern quadrant of the sky holds Orion, the Hunter, one of the brightest and most easily recognized constellations. Orion also serves as a pointer to several other constellations. The three equally bright, evenly spaced stars of Orion's belt point roughly toward Aldebaran, the alpha star in Taurus, to Orion's west, and toward Sirius, the alpha star in Canis Major, to the southeast. Sirius, also called the Dog Star, is the brightest star in the sky. Above Orion's belt are the stars of its shoulders: the brighter, eastern star of the two is the red star Betelgeuse; the other is called Bellatrix. Below the belt are two stars marking Orion's knees: the brighter, western one is the bluish-white star Rigel; the other is Saiph.
A line drawn from Rigel through Orion's belt to Betelgeuse and then extended northward points just north of Gemini, the Twins, and that constellation's two brightest stars, Castor and Pollux. Between Gemini and Canis Major lies the bright star Procyon, the alpha star in Canis Minor, the Little Dog.
There are few bright stars in the southwestern portion of the sky. The dim but large constellations of Pisces (the Fish), Cetus (the Sea Monster), and Eridanus (the River) span most of the western and southwestern sky. Near the meridian high in the south is Taurus, the Bull. The bright orange star Aldebaran marks its eye, and the V-shaped star cluster the Hyades marks its face. High in the southwest is the lovely star cluster known as the Pleiades, or the Seven Sisters. Almost overhead is Capella, the bright star in Auriga, the Charioteer.