Lecture Notes:

• We reviewed the relation between the altitude of the north celestial pole and latitude. In Boulder with a latitude of 40^o the north celestial pole is 40^o above the northern horizon. The celestial equator is always 90^o away from the pole and therefore the celestial equator is (90-latitude) degrees from the southern horizon. Declination of a star, planet, moon, or sun is measured above or below the equator. Thus at equinox the declination of the sun is 0, and in Boulder at noon of equinox, the sun is 500 above the southern horizon. At summer solstice, the sun has a declination of 23.5^o and thus has an altitude above the southern horizon of 73.5^o. At winter solstice in Boulder, the sun reaches only (50 minus 23.5) degrees, or 26.5^o above the horizon. The apparent movement of the sun eastward along the ecliptic is due to the revolution of the earth around the sun, which is counter-clockwise as viewed from above the north pole. The apparent movement of the sun throughout the day as it rises in the east, moves westward, and sets in the west, is, of course due to the rotation of the earth on its axis, which is also counter-clockwise as viewed from the north. [Jumping ahead to Mars: it has two small, dark moons, which are probably captured asteroids: Phobos and Deimos. Phobos, the closer moon, revolves around Mars faster than Mars rotates on its axis; Mars rotates at the same time as the earth, one terrestrial day, but Phobos goes around in about 1/3 of a day. As a result Phobos moves across the Martian sky from west to east, rising in the west! Very strange! Deimos, revolving in 11/3 days behaves "properly" and rises in the eastern horizon. How slowly would the earth have to rotate for our moon to appear to rise in the west?]

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• We looked at the following constellations: Orion, Canis Major, Canis Minor, Gemini, Auriga, Taurus, and Perseus, and at the following stars: Betelgeuse, Rigel, Sirius, Procyon. Castor, Pollux, Aldebaran, Algol and the clusters of the Hyades and the Pleiades.

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• There was a brief introduction to Southwestern archaeology: the period of time between A.D. 500-1300 is divided into four time slots: Basketmaker 500-700; Pueblo I, 700-900; Pueblo II, 900-1100, and Pueblo III, 1100-1300. The amazing roads and great houses of Chaco Canyon were built sometime in the Pueblo II period. The great kiva of Casa Rinconada may be a symbol of the joining of earth and heaven. The underground passageway may have symbolized the mythological entry of the ancestors into this world from the worlds beneath. Fajada Butte has a pecked spiral behind three large slabs of rock which marks the equinoxes and solstices. Chimney Rock Pueblo, high on a remote mesa, was apparently a lunar observatory. From Cliff Palace of Mesa Verde Anasazi astronomers could have observed the sun at winter solstice and the moon at major standstill setting behind the Sun Temple. In the square tower of Cliff Palace they marked the 18.6 year cycle of the moon, which is a real smoking gun in connection with their awareness of the lunar standstill cycle. More on this topic next week!