Tour One: The Plough and the North Pole
[Ursa Major, Ursa Minor, Bootes, Leo]
The 'saucepan' shape provides pointer stars to other objects. Starting from the two stars defining the right hand edge of the saucepan (Merek to the lower right, Dubhe to the upper right), extend a line 'upwards' from the pan (5x the distance between Merek and Dubhe) to reach Polaris, the pole star, and the tip of Ursa Minor (the Little Bear). Polaris is directly above the Earth's north pole, so all stars in the night sky appear to rotate around that one point as the Earth spins on its axis.
Returning to the Plough, we can now use the 'handle of the saucepan' as a pointer (the stars Mizar and Alkaid), directing us to Arcturus, the brightest star in the northern hemisphere in the constellation Bootes, the herdsman. Bootes may have been responsible for driving the oxen that the Greeks thought to represent the Plough. The constellation looks like a large kite extending up from the horizon, and Arcturus is an orange giant 37 light years from Earth.
Finally, if we drill a hole in the bottom of the saucepan, and let the liquid run out, it'll hit the head of the Leo the Lion, and the brightest star Regulus (a blue-white star 78 light years away marking the heart of the Lion), leading to the mnemonic: "A hole in the bowl will leak on Leo". Leo was the Nemean Lion killed by Hercules during one of his twelve labours, and cast into the sky, but looks to me like a coathanger bent out of shape. The Leonid meteor show November 14-15 comes from this direction.
Tour Two: Cassiopeia's Court
[Cassiopeia, Cepheus, Andromeda, Perseus]
Cassiopeia can also be used as pointer stars, although the directions aren't quite as obvious as for tour one. From the right hand side of the 'W', follow upwards towards the north to find Cepheus (Cassiopeia's husband and King of Ethiopia). Cassiopeia's punishment also extended to Ethiopia too, as Poseidon commanded the sea monster Cetus to attack.
Now extend the same line down (southwards) to find the feet of Andromeda (Cassiopeia's princess daughter). Cepheus was told that the only way to save his kingdom from attack by Cetus was to sacrifice his daughter, so Andromeda was chained to a rock to be eaten by Cetus. Andromeda is intimately linked to the brightest star in the Great Square of Pegasus. The Andromeda Galaxy (M31) is the closest spiral galaxy in the Milky Way and can be seen within the 'A' shape of Andromeda.
Finally, one of the central bars of the 'W' leads to the head of Perseus to the southeast. Perseus is the hero of our story, saving Andromeda from the sea monster Cetus using the head of Medusa to turn the monster to stone. Perseus became Andromeda's husband. The variable star Algol within Perseus is said to be Medusa's eye, and lies 93 light years away. The constellation is connected to Auriga to the east, and the Perseids' meteor shower (August 9-14) originates from this constellation each year.
Tour Three: The Summer Triangle
[Cygnus, Lyra, Aquila, Hercules and Pegasus]
Deneb is a bright star at the tail of Cygnus the Swan, a constellation lying in the plane of the Milky Way, and is easily recognisable due to the asterism known as the Northern Cross. Deneb is a blue white supergiant 3200 light years away. The beak is Albireo, a binary star of an orange giant and a blue-green star. Transformations of Greek gods into swans seemed a common occurrence, with Zeus, Orpheus and Cycnus all having gone through the process! The constellation contains the X-ray source Cygnus X-1, which is now thought to be caused by a black hole accreting matter in a binary star system.
Vega is in Lyra the Harp, a small constellation containing the 3rd brightest star in the northern hemisphere. After the deal of the musician Orpheus, his lyre was thrown into a river but retrieved by an eagle from Zeus, to be placed into the sky.
The final star in the triangle is Altair, a bright star within Aquila the Eagle. The eagle carried Zeus' thunderbolts. Like the Swan, the Eagle lies within the plane of the Milky Way so is rich with deep sky objects. Altair is one of the closest naked eye stars to Earth at a distance of only 17 light years. Interestingly, NASA's Pioneer 11 spacecraft (flew by Jupiter and Saturn in the late 1970s) is headed in that direction.
Both the Eagle and the Swan are flying in the direction of the Milky Way across the sky, and appear to be headed away from Cepheus (Cassiopeia's husband). Extending a line from Altair through to Deneb shows you the way to Cepheus (see Tour Two).
A line at right angles to this, coming out of the centre of the Summer triangle, will lead you to the Great Square of Pegasus, the winged horse. The square is made of four stars, alpha Peg, beta Peg, gamma Peg and alpha Andromedae, which it shares with Andromeda. 51 Peg features the first ever extrasolar planet to be discovered, and HD 2090458b provided the first evidence of water vapour from transit spectroscopy. Pegasus carried Medusa's head to Polydectes, and was a bearer of thunder and lighting for Zeus.
A final line from Deneb to Vega will point in the direction of a trapezium of four stars making up the body of Hercules, known as the Keystone asterism. Hercules is depicted as kneeling, praying to his father Zeus after winning a battle following his tenth labour.
Tour Four: Orion's Hunting Ground
[Orion, Canis Major, Taurus, Gemini]
Follow the belt to the left (southeast), and we arrive at Sirius, the brightest star visible in our night sky and part of Canis Major. Follow across the shoulders of Orion to the east and we find Procyon, part of Canis Minor. Canis Major and Canis Minor were the two hunting dogs of Orion. The Winter Triangle is made up of Sirius in Canis Major, Procyon in Canis Minor, and the red supergiant Betelgeuse, an asterism to rival the Summer Triangle. Voyager 2 is slowly moving towards Canis Major.
Follow the belt to the right (northwest) and find the red giant Aldebaran, the brightest star in Taurus the bull. Orion is typically depicted as fighting Taurus. Several objects of interest lie in this constellation, including the Crab Nebula (M1, a supernova remnant), the Hyades and the Pleiades. Keep on following the line through Taurus and you'll come to the Pleiades (M45), an open cluster of many stars, the seven most prominent giving the cluster its nickname. Zeus took on the form of a white bull to abduct the Phoenician princess Europa, but the identification of Taurus goes back must further into our history due to its position in the zodiac.
Now follow the Hunter's right arm upwards through the red giant Betelgeuse towards Gemini, the twins, and the two stars Castor and Pollux. Gemini is not in the plane of the Milky Way so features fewer deep sky objects, but is the origin of the Geminids meteor shower on December 13-14 each year. In Greek mythology, Pollux was the immortal son of Zeus and Leda, whereas Castor was the mortal son of Leda and the Spartan Kind, Tyndareus. When Castor died, Pollux begged his father to give Castor immortality, and the two were united in the heavens.
Finally, a further asterism known as the Winter Hexagon can be found by connecting Sirius to Rigel, Aldebaran, Capella, Pollux and Procyon, with Betelgeuse roughly in the centre.
General Star Charts (Summer/Winter)
|To give a sense of how all of these star hopping tours fit together, here's a star chart for the northern hemisphere constellations in mid-summer.|
|...and another for mid-winter.|
Some Helpful LinksSuperb Stargazing Live guide from the BBC:
Dave Snyder's 2003 guide to the constellations http://www.umich.edu/~lowbrows/guide/constellations.html
Sky maps and planispheres from http://www.topastronomer.com/
A great beginners guide to constellations from Astronomy.com
Visualisations of what the constellations really look like: http://www.allthesky.com/constellations/visualconstellations.html