Today! From Earth’s Perspective: Celestial Motion: Stellar Motion Solar Motion Planetary Motion

Celestial Motion Some stars and constellations Are circumpolar—never rise or set. Celestial Motion

Constellation vs Asterism!

A constellation is one of 88 listed ‘states’ or regions in the sky: like Orion.

An asterism is not on the list Of 88, but forms a shape In the sky: like the Big Dipper, Part of the constellation Ursa Major.

Finding Planets: Once you find the North Star, Turn around 180 degrees— The Ecliptic and the planets will be in the sky toward the South. Finding Planets:

The stars (at a given time of night) shift 1 degree a day Because the earth is orbiting the sun. Thus the sidereal day is 23 hours and 56 minutes: It is the time for a star to return to the same place In the sky.

Solar motion: Mean solar day--24 hours by definition. Return of sun to same angle of view relative to the horizon.

seasons caused by tilt of earth’s axis, solstices--maximum and minimum light, equinoxes equal light on northern and southern hemisphere.

Planetary motion: retrograde motion--apparent backtracking of planets in sky from earth's perspective. inner planets--Me and Ve --stay within 'maximum elongation'. conjunction vs opposition

Mercury 8/30/02 Above Cloud Center w/ Venus Upper Left