Lecture 8 – Astronomical Objects and Their Motions in the Sky
Summary / Checklist of the Main Concepts to Understand and Remember

Daily Motions in the Sky, and the Sun  
• What is the difference between a solar day and a sidereal day? (How long is each one, and why do they differ.)  
red bullet How do astronomical objects (the Moon, stars, planets, ...) move in the sky over a few hours in one night?  
red bullet How do astronomical objects move on the Celestial Sphere over a few hours in one night?  
red bullet What is the difference between motions in the sky and motions on the Celestial Sphere?  
     
Motions over Longer Periods of Time  
• Do stars rise in the sky at the same time every day?  
• Why do the visible constellations in the sky change gradually during the year?  
red bullet How do stars move on the Celestial Sphere over periods of weeks or months?  
red bullet How do planets move normally on the Celestial Sphere, over periods of weeks or months?  
• When do we say that a planet's motion on the Celestial Sphere is retrograde?  
red bullet Why do all planets move approximately along the ecliptic, as seen from Earth?  
• How is the period of time we call a month related to astronomy?  
• How is the period of time we call a year related to astronomy?  
     
     

Topics from the lecture page and textbook not listed above [or between square brackets] were not covered in class;
Underlined words indicate that I will expect students to remember a number or a name related to that topic.

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