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STARGAZERS TIMELINE 1IMIM 500 BCE Pythagoras thought planets made “Music of the Spheres.” He believed the universe was mathematical in nature. 432 BCE Meton introduces his calendar in Athens. 270 BCE Aristarchus proposes the Earth orbits the Sun. He estimates the Sun’s distance and size. 250 BCE Eratosthenes estimates the size of the Earth. 135 BCE Hipparchus discovers equinoctial precession . He estimates the distance between the Earth and the Moon. 46 BCE Julius Caesar reforms the Roman Calendar. 140 CE Ptolemy writes "He Mathematike Syntaxis."

Index Stargazeres Timeline 1 444 Calendar History 1 333 Calendar History 2 333 Atmosphere 333 Tycho Brahe It compiled astronomy from Greece and Babylon. 820 CE Caliph Al Ma'mun established the "House of Wisdom". Al Khorezmi becomes chief mathematician. He introduced the Indian numbering system. He also introduced decimals and the zero. The word “algorithm” comes from his name. 1054 CE A supernova appears in Crab constellation. Chinese astronomers call it the "guest star." 1543 CE Nicholaus Copernicus published his solar system theory. He believed the universe centered around the Sun. 1572 CE Tycho Brahe observes a supernova. He calls it a nova meaning “new star”. Source NASA Speed Learning Format Carl Peterson Ó2005

CALENDAR HISTORY 1 Meaning Clusters The early Egyptians made a calendar of 365 days. It had 12 months of 30 days plus five holidays at the end of the year. Our day of 24 hours also came from this calendar. Our system of 24 hours comes from Egypt. Around the 3000 B.C., the Egyptians used a calendar in which each month was divided into three periods of 10 days each. Now consider that all stars move in a yearly cycle, due to Earth's motion around the sun. The first appearance of a star before sunrise at the start of its new season of visibility is known as its heliacal rising. The Egyptians came to associate the heliacal rising of a particular bright star with each of their 10-day periods over the course of a year.

MEMORY TRIGGERS Egyptians________________________ _________________________________ 12 months________________________ _________________________________ 24 hours_________________________ _________________________________ calendar_________________________ _________________________________ month___________________________ _________________________________ stars____________________________ _________________________________ sunrise__________________________ _________________________________ heliacal__________________________ _________________________________ 10-day periods____________________ Copyright 2005 by Carl Peterson

CALENDAR HISTORY 2 Meaning Clusters Egypt associated night with 12 stars that rose in summer months. Egyptians divided the period from sunrise to sunset into 10 parts. They added an hour before sunrise and after sunset for twilight periods for a total of 24 hours in a day/night period. The length of these original "hours" changed with the seasons. They were called "seasonal" hours. Hours of equal length were introduced by Greek astronomers. But as late as the Middle Ages, when mechanical clocks came into use, seasonal hours were still used in everyday life.

MEMORY TRIGGERS 12 Stars__________________________ _________________________________ Egyptians________________________ _________________________________ sunrise__________________________ _________________________________ twilight__________________________ _________________________________ "hours"_________________________ _________________________________ Greek___________________________ _________________________________ Middle Ages______________________ _________________________________ seasonal hours____________________ _________________________________ Copyright 2005 by Carl Peterson

ATMOSPHERE 1 Meaning Clusters Density and composition of the Earth’s atmosphere differs as the altitude increases above the surface. The troposphere extends from the surface to 10 km. The gases common in this region are molecular oxygen and nitrogen. 90% of the atmosphere, 99% of the water vapor and all weather is found in the Troposphere. Above the troposphere, the stratosphere extends from 10 km to about 50 km. Solar radiation breaks molecular oxygen into individual oxygen atoms in the stratosphere. These oxygen atoms may combine with an oxygen molecule to form a molecule of ozone. At heights above 80 km, free electrons in the thin gas exist for short periods of time before a positive ion captures them. These charged particles indicate the beginning of the ionosphere.		MEMORY TRIGGERS TESTS Density_____________________________ ___________________________________ troposphere_________________________ ___________________________________ ______________molecular_____________ ___________________________________ ___________________weather_________ ___________________________________ ____________________stratosphere_____ ___________________________________ Solar radiation______________________ ___________________________________ oxygen atoms________________________ ___________________________________ _________________free electrons_______ ___________________________________ charged particles____________________ ___________________________________ Source NASA Speed Learning format by Carl Peterson ©2005
TYCHO BRAHE 1546—1601 Danish astrologer, astronomer, alchemist At age 17, frustrated by disagreement among astronomical charts, he determined to systematically study the stars Improved and enlarged measurement instruments and invented new ones In 1572 he noticed a bright star appear in constellation Cassiopeia Coined the word “nova” for “new star” (today, a supernova) His observations were the most accurate before the invention of the telescope King of Denmark and Norway built two observatories research institute for Tycho Brahe Johannes Kepler was his assistant Moved to Prague in 1599 Rudolf II built a new observatory for him In return Brahe prepared astrological charts for his patron He also did weather forecasting	MEMORY TRIGGERS Danish_________________________________ ______________________________________ Astronomer____________________________ ______________________________________ Astrologer______________________________ _______________________________________ Astronomical charts_______________________ _______________________________________ Instruments______________________________ _______________________________________ Cassiopeia______________________________ _______________________________________ Nova___________________________________ _______________________________________ Telescope_______________________________ _______________________________________ Kepler__________________________________ _______________________________________ Research________________________________ _______________________________________ Astrological charts________________________ _______________________________________ Weather________________________________ _______________________________________