A Tour of the Sky
Summary: There are many interesting objects in the Autumn/Winter (Fall semester) and Winter/Spring (Spring semester) sky. Here are a few of the brighter stars and more easily recognizable constellations that you should become familiar with. Knowledge of these features can help you navigate your way around the sky to fainter objects as well as help you get a good grade on your practical. You can "take this tour" on your own, try it with a friend, or walk through it with your TA. Your star finder or the star charts will greatly help in following this self-guided tour.
Grading: Ungraded. You should become familiar enough with the sky to be able to use your star dials and telescope. To do this, you need to learn some star and constellation names and be able to find them in the nighttime sky.
Good Luck: Although there are many, many more constellations in the sky than the ones described below, if you know these, you will be able to navigate to just about anywhere you want. You can identify other stars and constellations by consulting the various maps you are given or your T.A.
- All Seasons Sky Tour
- Winter/Spring Sky Tour (Spring Semester)
- Autumn/Winter Sky Tour (Fall Semester)
ALL SEASONS SKY TOUR
The Big Dipper and Ursa Major: An east way to get started is to identify the Big Dipper. It will be approximately north, so get your bearings and scan in that direction. In the spring, it is found in the North-East, "standing on its handle." The Big Dipper, contrary to popular belief, is not a constellation. It is what is known as an asterism or distinctive grouping of stars. There are many asterisms, and most of them are only part of a larger constellation. The constellations are defined groupings of stars that sometimes make a recognizable outline of the object for which the constellation is named. They are primarily modeled after mythological figures, animals or objects. The Big Dipper is part of a very large constellation called Ursa Major, the great bear. She was one of the former human lovers of Zeus who was transformed into a constellation by an angry Hera. The stars of the Big Dipper are (starting from the end of the handle): Alkaid, Mizar, Alioth, Megrez, Phecda, Merak, and Dubhe.
Finding Polaris and the Little Dipper: Make a line connecting Merak to Dubhe (called the pointer stars) and extending out of the "bowl." Continue long this line, crossing an area of the sky rather devoid in stars until you get to a relatively isolated star slightly fainter than Merak. This is Polaris, the North star. It is in the constellation Ursa Minor, the little bear, and part of the asterism known as the Little Dipper. He was the son of the great bear. Zeus changed him into a constellation to be with his mother. Polaris is the star at the end of the handle of the Little Dipper, and the other bright stars. There are only two other bright stars in the Little Dipper, Kochab (the brighter of the two) and Pherkad, both at the end of the bowl.
Finding Cassiopeia: The brighter stars of Cassiopeia form an easily recognized asterism in the shape of an "M" or "W." Relative to Polaris, it is diametrically opposed to the handle of the Big Dipper. Cassiopeia was the queen of Ethiopia, and mother of Andromeda. This constellation has two bright stars (the right side of an upright "W") called Caph and Shedar. Professor Weintraub has always considered Cassiopeia to be his family constellation.
Finding Cepheus: Continue along the line you drew from the pointer stars to Polaris until you get to a constellation that looks like a child's drawing of a house (triangle on top of a square). This is Cepheus, the king of Ethiopia and father of Andromeda. Cepheus has one bright star, Alderamin, at the bottom right of the house as viewed from an upright drawing.
WINTER/SPRING SKY TOUR (Spring Semester)
The Winter Hexagon and the main winter constellations: The winter sky is filled with very bright stars, several of them forming a very large asterism known as the "Winter Hexagon." Each of its six stars actually belongs to a different constellation. Once you have identified this hexagon in the sky, you can use it to find most of the winter and a few of the spring constellations. The hexagon is somewhat taller than wide, and it stands on one of its points. It is VERY large, nearly covering a 90 degree angle in height. The star at the top of the hexagon is Capella (the Goat) in the constellation Auriga (the Charioteer). It is a very bright yellow star and it remains nearly overhead for the entire Spring semester. About 30 degrees to the lower right of Capella is the bright orange star Aldebaran, the "Red eye of the Bull," in the constellation Taurus . About 30 degrees below Aldebaran is the bright blue star Rigel, in the constellation of Orion, the mighty hunter. The bottom of the hexagon, in the southern part of the sky, is represented by the brightest star in the sky, Sirius, in the constellation of Canis Major , the great dog. Going back up to the upper left of Sirius is a bright white star, Procyon, the head of Canis Minor, the little dog. The two dogs belong to the hunter Orion, who is facing the charging bull. This celestial drama plays itself out rather slowly, however! Above Procyon is a pair of stars, Castor and Pollux, which form the sixth apex of the hexagon. They are part of the constellation Gemini , the twins, the stars representing the heads of the two brothers. Returning to Capella completes our stroll around the winter hexagon.
Taurus and the Hyades and Pleiades star clusters: You may be able to see several fainter stars around Aldebaran forming a distinctive "V," with Aldebaran at the tip of one of the branches. These are members of the nearest star cluster, known as the Hyades . These form the head of the bull. To the upper right of the Hyades is another distinctive, but smaller and tighter grouping of stars, the Pleiades. The Pleiades looks like a tiny little dipper and is often referred to as the seven sisters.
Orion: In the middle of the hexagon is a bright orange star, Betelgeuse, which, along with Rigel form two diagonally opposite corners of a rectangle of bright stars. In the middle of this rectangle is a striking asterism of 3 stars, aligned, regularly spaced, and of similar brightness. This is the "belt of Orion." Betelgeuse represents a shoulder and Rigel one of Orion's legs. The rectangle and the belt are the brightest stars of the constellation Orion. Below the belt, in the lower part of the constellation is a faint group of stars. Binoculars or a telescope will reveal the presence of the famous Orion nebula, a cloud of gas and dust where a vast number of stars are currently forming.
Leo: The rising of Leo (the lion) in the Eastern sky signals the arrival of spring in the northern hemisphere. About 25 degrees to the East of Procyon and the pair Castor and Pollux, across an "empty" part of the sky, is the bright white star Regulus, the "heart of the lion." Regulus is at the bottom of an interesting asterism shaped like a reversed question mark (?). This represent the head of the lion. Following in the sky (to the East) is the rest of the body, ending at the bright tail star Denebola. The constellation Leo generally lies below the bowl of the Big Dipper.
AUTUMN/WINTER SKY TOUR (Fall Semester)
The Great Square of Pegasus, Andromeda, and Perseus: Go back along the first line for a good ways until you get to a large square. This the the asterism, the Great Square of Pegasus, in (you guessed it) Pegasus, the winged horse that sprang from Medusa's blood when Perseus killed her. It is composed of the four stars (clockwise starting from the star closest to the line) Scheat, Markab, Algenib, and Alpheratz. Alpheratz is actually in the constellation Andromeda, the princess, who was saved by Perseus from the monster Cetus (the Whale). Andromeda's main feature is a line of bright stars starting with Alpheratz and extending away from the square. The two brightest in this line are Mirach and Almach. This line of Andromeda points to the heart of Perseus, a hero of many legends. At this heart is the star Mirfak, and radiating away from Mirfak are three bent prongs. The only other really bright star in Perseus is Algol, the demon star.
The Summer Triangle: the stars Deneb, Altair and Vega and the Constellations Cygnus, Aquila and Lyra: Now go back to Polaris. Make a line starting at Polaris, curving through Cepheus away from Cassiopeia until you get two a very large triangle of three of the brightest stars in the sky. This asterism is known as the Summer Triangle. The faintest of the three stars is Deneb, which is the 19th brightest star in the sky, in the constellation Cygnus, the swan. Cygnus was formerly a human who searched diligently for Phaeton's body after Phaeton fell from Apollo's Sun chariot. It is also known as the Northern Cross asterism due to the fact that the central part of the constellation looks like a cross. Deneb is at the top of the cross which is composed of 3 stars in a line going down from Deneb and 2 stars on opposite sides of the second star in Deneb's line. The star Sadr is at the point of intersection of the cross and the star Albireo is at the bottom of the cross. The second brightest star in the Summer Triangle is called Altair. It is the 12th brightest star in the sky and resides in the constellation Aquila, the eagle. Aquila has a rather odd shape that looks vaguely like a bow with notched arrow. The brightest star in the Summer Triangle is the star Vega, the 5th brightest star in the sky. It is in the constellation Lyra, the lyre. Lyra is composed of an intersecting parallelogram and triangle of relatively faint stars.
Finding Aquarius and Pisces:
Now go along the left side of the cross (as viewed if the cross were upright) and continue until you get to a faint 'Y' shaped asterism known as the Water Jar. It is in the constellation Aquarius, the water bearer, one of the zodiacal constellations. Keep going along this line till you get to a bright star just near the southern horizon. This is Fomalhaut, the 18th brightest star in the sky. Fomalhaut lies in the constellation Piscis Austrinus, the southern fish.
Hercules, Draco, Bootes and Virgo:
Go back to the dippers again. From Kochab and Pherkad (the bowl of the little dipper) make a line going away from Polaris. Continue until you get to a relatively faint trapezoidal asterism known as the Keystone. It forms the central part of the constellation Hercules, another popular figure in Greek mythology. About halfway between Kochab and Vega is the star asterism known as the Lozenge of Draco. It is actually the head of the Dragon, whose tail winds between the two dippers. Go to the Big Dipper and make an arc from the stars in the handle. Continue this arc away from the bowl until you get to a really bright, golden star. This is the star Arcturus, the 4th brightest in the sky, in the constellation Bootes, the herdsman, legendary inventor of the plow. Keep following this arc until you get to a slightly fainter, bluish-white star. This is Spica, the 16th brightest star in the sky, in the zodiacal constellation Virgo, the virgin.