Astronomy 1021 Chapter Notes - Chapter 1: Dark Matter, Local Group, Dark Energy

• School: Western University
• Department: Astronomy
• Course: Astronomy 1021
• Professor: Robert Cockcroft

Document Summary

Astronomy 1021 chapter 1 reading notes: a modern. Earth moves through rotations (spins) and yearly orbits (also known as revolution) around the sun: earth rotates once a day, rotates from west to east. Explain why sun rises from the east and sets in the west: counter clockwise, earth orbits around the sun once a year. Average distance from the earth and sun is 1 au = 150 million km. It travels/ moves 100,000 km/hr: ecliptic plane: the plane of earth"s orbit around the sun. Earth"s axis is tilted at 23. 5 degrees from a line perpendicular to the ecliptic plane: axis tilt: the amount by which a planet"s axis is tilted with respect to a line perpendicular to the ecliptic plane. Axis points almost directly at a star called polaris or the north star. Earth rotates counter clockwise around the sun: note: this was actually a consequence of the way the earth was born.