AS101 Lecture Notes - Lecture 1: North South Mrt Line, Leap Year, Right Ascension
Document Summary
1 astronomical unit = 1 au = 1. 5 x 108km = 150m km = average distance from sun to the earth. Light-year (ly) = the distance light travels in one year, approx. It has been approximately 13. 7b years since the big bang. The moon"s distance from earth is about 30x the earth"s diameter = 384,000km. The precession of the earth"s rotational axis points to the north star but this will change over time. The sun rises in the east and sets in the west. The earth rotates from west to east in front of the sun, giving both day and night. What you see in the sky depends on where you are; canadians see constellations and stars that australians never see. Astronomers measure distances across the sky as angles in units of degrees, arc minutes and arc seconds. Zenith point in the sky directly overhead. Celestial equator an extension of the earth"s equator onto the celestial sphere.
