ASTR 151 Study Guide - Midterm Guide: Sidereal Year, Celestial Equator, Tropical Year
Document Summary
Sidereal day once stars are in the same place as rst observation. Thirteen constellations sun moves through during the year is called zodiac. Ecliptic plane of earth"s path around the sun is . Northern most point of path - above celestial equator is . Points where path crosses celestial equator are and vernal and autumnal equinoxes. Combo of day length and sunlight angle gives seasons. Time from one vernal equinox to next is tropical year. Time for earth to orbit once around sun, relative to xed stars, is sidereal year. Sidereal year rotation of earth"s axis itself; makes one complete circle in about 26,000 years. Moon takes about 29. 5 days to go through a whole cycle of phases called synodic month. Time to make full 360 degree rotation around earth, . , is about 2 days shorter sidereal month. When only part of moon is in shadow. When it all is in shadow total. When only part of sun is blocked.
