ASTRO 1 Chapter 2: 2. Knowing the Heavens
Document Summary
Stars move in counter-clockwise circles around a fixed point above the northern horizon. 2-1 naked-eye astronomy had an important place in civilizations of the past. Positional astronomy: the study of the positions of objects in the sky and how these positions change. : the idea of dividing the sky into constellations. Human eye: detect about 6000 stars -half of the sky below the horizon-> only 3000 stars. Every stars lies in one constellations or another. The constellation orion is easily seen on nights from dec. through mar. Betelgeuse (a orion): the brightest star in orion. 2-3 the appearance of the sky changes during the course of the night and from one night to the next. Earth rotates once a day around an axis from the north pole to the south pole (from west to east) Earth orbits / revolves once a year around the sun. Star rises approximately 4 minutes earlier each night / 2 hours earlier each month.
