Lecture Notes

1. CONSTELLATION OF THE WEEK:
   The super-constellation of the Winter Triangle consisting of Betelgeuse, Sirius, and Procyon.
   
   
   • SIRIUS, also known as alpha Canis Majoris; the BRIGHTEST star in our night sky with a magnitude of -1.5 is also one of the closest (it is the sixth closest star to the sun). In Greek Sirius means sparkling or scorching. The Egyptians called it after their god Osirus; the Arabs know it as Al Shira. Its name probably comes from an even older tongue, namely Sanskrit and it may be associated with the name of the sun god of India, Surya.
     
     In Egypt it was also known as the Nile star as it rose heliacally at summer solstice around 3000 B. C. close to the day of the all important rising of the Nile.
     
     Sirius has a luminosity 2.3 that of the sun; a diameter 1.8 that of the sun and a temperature of 10,000K.
     
     Sirius has a white dwarf companion Sirius B, which orbits Sirius A in 50 years; its highly compressed material is so dense that a teaspoon would weight as much as the space shuttle. It is a star what has collapsed to the size of a planet and is cl ose to death. The telescopeless Dogon tribe of Mali in west Africa have a tradition that Sirius, which they worship, has a companion made out of strange and heavy matter. Sirius B has a magnitude of 8.8 and is normally invisible in the glare of the much brighter Sirius, so it is a fascinating mystery that the Dogons know of the white dwarf.
     
     

     PROCYON: "Before Sirius", slightly west of Sirius, it rises ahead of that star. Procyon has a luminosity 6 times that of the sun, a diameter twicethat of the sun and a temperature of 7000K. It lies at a distance of 11.4 LY; also known as alpha Canis Minoris, it also has a white dwarf companion with a period of 40 years.
     
     

     BETELGEUSE: "The Armpit of the Great One", is my favorite translation, of this LARGEST star that we can see without a telescope. It is a pulsating variable red supergiant, which varies in size from the orbit of Mars to the orbit of Jupiter, ranging in size from 550-920 that of the sun and a luminosity ranging from 7600 to 14,000 that of the sun. It is red because it is very cool, only 3100K. Some time in the future, it will blow up as a supernova, and give our grandkids or generations beyond a sight to knock their socks off!

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2. LABORATORY EXPERIMENT: THE TEMPERATURE OF THE SUN.
   Use a remarkably simple approach to measure the suns temperature. Our eyes have the same color sensitivity as the color distribution of the sun. We are children of the sun!. For comparison, we list the sun relative to the start of the Winter Triangle:
   
   
   • Sirius: 10,000K
   • Procyon: 7000K
   • Sun: 5800K
   • Betelgeuse: 3100K
   
   Good luck in measuring the correct temperature!

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3. CYCLES OF THE MOON.
   • Sidereal period = 27.3 days
   • Synodic period = 29.5 days, longer because the moon must catch up with the earth as we revolve around the sun. This is the period between two full moons, or two new moons..
   • The full moon occurs when the moon is in opposition to the sun. That condition means that the full moon is always doing the opposite of the sun. It rises when the sun set; sets when the sun rises. The full moon is furthest north in mid-winter when the sun is furthest south. Lunar standstills: Major standstills occur every 18.61 years, at which time the moon reaches at times during its cycle a maximum declination of 28.6 degrees. At the time of major and minor standstills, the eclipse seasons occur at equinoxes. This behavior may have been known by Chacoan astronomer-priests and may have been used by them to organize winter solstice festivals at the time of full moon, when there would not be an eclipse. Halfway between major and minor standstills, the eclipse seasons occur at solstices and there is the danger that a winter solstice festival would be disrupted by an inauspicious eclipse" "off with his head" ! Not as good time to be a Chacoan astronomer-priest! The clever organizer would schedule the festival one day on either side of full moon during such a time.