ASTR 3 Lecture Notes - Lecture 1: Bacteriophage, Celestial Sphere, Frant
Document Summary
Light year: distance traveled by light in a year. December: capricorn/sagitarious right across and visible but behind us is gemini. September : virgo right across and visible but behind us is pisces. June: gemini right across and visible but behind us is capricorn. Celestial sphere: believed stars were attached to move around a fixed earth. Constellations move across the sky from e to w. Motion of stars are because the earth rotates making it seem as the stars move when in reality they are stationary. Right ascension: longitude measured in hours declination: latitude measured in degrees . N&s celestial poles: where the earth axis intersects celestial sphere. Celestial equator: intersection of earths equatorial plane with the celestial sphere. Each degree can be subdivided into 60; arc minutes. Arc minutes : 60"" arc seconds (centimeter sized objects) Stars positions do not repeat one night to the next. Sidereal day: day measured by stars (4 minutes shorter)
