AST101H1 Lecture 4: Lecture 4 - Night Sky Constellations and Seasons - September 19.docx

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Michael Reid

Document Summary

Lecture 4 the night sky, constellations, and seasons. The orbit is almost circular, it"s not about distance between the earth and sun. It"s about the amount of energy reaching/touching the earth"s surface: per unit area. Earth is tilted by 23. 5 degrees, seasons are determined by which hemisphere is tilted towards/away from the sun. Do other planets have seasons: jupiter"s tilt is 5 degrees, no seasons. The plane where the earth moves around the sun is called ecliptic. We invent the term celestial sphere to define the dome of stars surrounding earth, even though it"s not a dome at all. Certain sections of the night sky are not visible to certain locations on earth depending on what hemisphere you"re in. If you"re at the north pole, you won"t be able to see sections of the celestial sphere that surround the south pole.