Earth, Sun, and Moon Interactions Unit 1- Astronomy Earth, Sun, and Moon Interactions

Rotation Spin/turn on an axis Earth’s tilt or axis is 23.5⁰ from the equator One rotation = one solar day (24 hrs/day) Foucault Pendulum- evidence of Earth’s rotation on its axis

Revolution Move around an object; to orbit A path the Earth follows around the sun Takes 1 year or 365.25 days for Earth to travel around the Sun Causes seasons

Solstice Summer Solstice- Winter Solstice- Sun directly overhead at Tropic of Cancer 23.5 ⁰ north latitude June 21 each year Maximum daylight hours in northern hemisphere Winter Solstice- Sun directly overhead at Tropic of Capricorn 23.5 ⁰ south latitude December 21 each year Minimum daylight hours in northern hemisphere

Equinox Vernal (Spring) and Autumnal (Fall) Equinox “Equal night”- 12 hours of daylight, 12 hours of night Earth’s axis is NOT pointed at the Sun Both hemispheres receive equal amounts of sunlight

Plane of Ecliptic = the plane in which Earth orbits around the Sun

Stop to Summarize 1.) What’s the difference between rotation and revolution? 3.) How does the Earth’s tilt influence the equinoxes and solstices?

Earth’s Shape OBLATE SHEROID Equatorial Bulge- flattened sphere along the axis from pole to pole such that there is a bulge around the equator. - caused by the rotation of the Earth - the diameter at the equator is 43 km (kilometer) larger than the pole-to-pole diameter.  

Precession Precession Slow and continuous change in the orientation of a Earth’s rotational axis Caused by the gravitational pull between the Sun and the Moon Changes the stars near the Pole Like a rotating toy top Occurs over a period 26,000 years