ASTRON 1F03 Lecture Notes - Lecture 1: Celestial Sphere, Sidereal Time, Distant Star
12 Mar 2018
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Document Summary
The naive view of the universe: what we see in the sky are the projections of stars that are much further away. They appear to be closer to each other and to the earth: celestial sphere: the sphere that appears to be formed by the sky, on which stars lie. Useful to detect their position using 2-d spherical coordinates: as earth rotates, we see different stars during the day/night. The apparent motion of these stars is the counterclockwise motion of the celestial sphere: declination: distance north or south in degrees from the celestial, right ascension: distance eastward of the vernal equinox. Every day the earth revolves around the sun by (360/365)* = 0. 986*. If it takes 24 h to rotate 360*, it takes. The solar day is 4 min longer than the sidereal day: as the earth revolves around the sun, the sun"s position relative to the stars seems to change (the earth actually moves).
