The Ten Brightest Stars in the Winter Sky Asterisms and Their ConstellationsOBSERVING THE SKY;THE BIRTH OF ASTRONOMY, PART I:INTRODUCTION TO THE SKYJanuary 18, 2005Chapter 2, Pages 18─29Thursday: Chapter 2, Pages 29─41I. Patterns in the sky; constellations A. Greek/Roman constellations and other myths and legendsB. Creation of Universe (Earth, Sun, Moon, stars)C. Stories with moral/lessonII. Motion and cyclesA. Cycles (lunar phases, day/night)B. Importance: time (Big Dipper); seasons (Big Dipper, Scorpius); harvest/plant (Pleiades)II. Size and shape of stars on chartsIII. Asterism vs. constellation: Pleiades; Big/Little Dipper vs. Ursa Major/ Ursa Minor (Big and Little Bear); Winter Hexagon (Auriga, Gemini, Canis Minor, Canis Major, Orion, Taurus)IV. Orion, measuring anglesV. 3-D nature of constellationsTHE WINTER/SPRING SKYThe brightest stars of the winter/early spring sky (see chart below) are found in the following constellations:Orion (the hunter) Auriga (the charioteer)Taurus (the bull) Canis Major (the big dog)Gemini (the twins) Canis Minor (the little dog)These constellations can be found almost directly overhead at 9:00 p.m. There are 88 officially designated constellations.The area of the sky surrounding and including the constellation is called by the constellation’s name. This helps astronomers describe the locations of objects in the sky.The brightest star in Orion is Rigel; the brightest star in Taurus is Aldebaran; and the brightest stars in Gemini are Pollux and Castor; the brightest star in Auriga is Capella; the brightest star in Canis Major is Sirius; the brightest star inCanis Minor is Procyon. When connected, the seven brightest stars in these six constellations form an asterism called the Winter Hexagon. An asterism is an easily recognized shape made from the brightest stars of one or more constellations. Sirius, Procyon and Betelgeuse (the second brightest star in Orion) form an asterism known as the Winter Triangle. From a dark site, the Milky Way can be seen between Sirius and Procyon. In some Native American sky lore, the Milky Way is thought to be a trail of cornmeal spilled by a dog. Sirius, in Canis Major, represents the mischievous dog. In ancient Arabian sky lore, the Milky Way represents a river that separates two sisters. One sister is represented by Sirius,and the other by Procyon.1/14/2019, 7:47 AM1The Pleiades, or Seven Sisters, appears within the constellation Taurus. The Pleiades is actually an open star cluster, which is a group of stars that formed within a nebula. The Pleiades usually appears as a fuzzy patch, but most people can distinguish 5 or more individual stars even from a moderately dark site. The Hyades is another open star cluster, which makes up the face of Taurus. Aldebaran is a red-orange giant star within this cluster, and is often called the eye ofTaurus.Many so-called stars are actually double stars. Double stars are actually two stars orbiting around a common center. They appear as a single star without the aid of a telescope. Capella, Sirius, and Procyon are double stars. Castor is a multiple star: three double stars in one. Pollux, the other twin of Gemini, is a single yellow giant star which appears even brighter than Castor’s six stars.Looking north at about 9:00, you will see the circumpolar constellations. These are the constellations that appear to circle Polaris, the North Star. The W shape of Cassiopeia (the queen) is upside down now, looking more like an M. Cepheus (the king) is below Cassiopeia. It is shaped like a house with the point of the roof approximately toward Polaris.Ursa Major (the great bear) is visible to the north with the handle pointing toward the horizon. From a very dark site, Ursa Minor (the small bear) may be visible below Polaris. Within these constellations, there are two familiar asterisms: the Big Dipper in Ursa Major and the Little Dipper in Ursa Minor. The bowl of the Big Dipper is formed by four prominent stars which also form the rear portion of the bear’s body. The handle is formed by three prominent stars which form the bear’s tail. From even a moderately dark site, a second star can be seen near the center handle star. These stars are Alcor and Mizar. The best known star in the Little Dipper is at the end of its handle: Polaris, the North Star or Pole Star. Its overall shape is similar to the Big Dipper, except that its handle curves in the opposite direction.By 10:00, Leo (the lion) is rising in the East. The head and neck of Leo look like a backwards question mark. If you imagine someone poking holes in the bottom of the bowl of the Big Dipper, the water would drip onto Leo’s back. Regulus is the brightest star in Leo.The Ten Brightest Stars in the Winter Sky Asterisms and Their ConstellationsStar Constellation Asterism Constellation(s)Sirius Canis Major Big Dipper Ursa MajorCapella Auriga Little Dipper Ursa MinorRigel Orion Winter Hexagon Auriga, Taurus, Orion, Procyon Canis Minor Canis Major, CanisBetelgeuse Orion Minor, GeminiAldeberan Taurus Winter Triangle Canis Major, CanisPollux Gemini Minor, OrionAdhara Canis Major Orion’s Belt OrionCastor Gemini “M,” “ W” CassiopeiaBellatrix Orion Question Mark Leo1/14/2019, 7:47
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