Earth and Space Science Origin of Modern Astronomy Chapter 22

22.2 The Earth-Moon-Sun System I. Motions of Earth –A. ___________________ – the turning, or spinning, of a body an its axis. Gives us day and night Each rotation takes _________________ _______________________ – time interval from one noon to the next – nearly 24 hours _____________________ – the time it takes for Earth to make one complete rotation with respect to a star other then the sun –23 hours, 56 minutes, 4 seconds

22.2 The Earth-Moon-Sun System –B. _________________ – the motion of a body, along its orbit around some point in space. Earth moves 107,000 km/hr Average distant from sun is 150 million km The orbit is an ellipse, which means it is closer at some times than at others. ________________ – Earth is closest to sun –Occurs on January 3 each year _________________– Earth is farthest from sun –Occurs on July 4 each year

22.2 The Earth-Moon-Sun System –The Seasons – The imaginary line that connects Earth’s orbit with the celestial sphere is the plane of the ecliptic The celestial equator is the projection of the Earth’s equator on the sky. The Earth’s tilt on its axis is __________ When the sun’s apparent position is plotted on the celestial sphere over a period of a year’s time, its path intersects the celestial equator at two points: the spring equinox and the autumn equinox.

22.2 The Earth-Moon-Sun System –At two other times of the year the sun appears 23.5ô north and south of the equator Summer and winter solstice –C. ____________________________ – the slight movement of Earth’s axis Over a period of 26,000 years.

22.2 The Earth-Moon-Sun System II. Earth-Sun motions –A. The entire solar system moves in the direction of the star Nova –B. The Milky Way Galaxy is also in motion – towards to Andromeda Galaxy –C. These speeds are very great.

22.2 The Earth-Moon-Sun System III. Earth-Moon motions –A. The Earth has one natural satellite – the moon. –B. The Moon orbits the Earth in a period of about one month. –C. It’s motion is counterclockwise around the Earth. –It’s orbit is also elliptical Perigee – _____________________ Apogee- ____________________

22.2 The Earth-Moon-Sun System IV. Phases of the Moon –A. The changes in the amount of the moon that appears lit. _____________– when the moon is between the Earth and the sun – we cannot see the lit portion –It appears like there is no moon at all in the sky ________________– small sliver that approaches the first quarter. ______________– half circle – right side lit

22.2 The Earth-Moon-Sun System ____________– from first quarter to full moon. _____________– when the Earth is between the moon and the sun. –we see the whole lit portion of the sun ______________– moving from full moon the third quarter. ______________– half circle – left side lit ___________________– from third quarter to new moon.

22.2 The Earth-Moon-Sun System The moon’s period of rotation and its revolution around the Earth are the same –That is why we see the same side of the moon all the time. –271/3 sidereal month –291/2 synodic month

22.2 The Earth-Moon-Sun System V. Eclipses – shadow effects –A.__________________– when the moon is between the Earth and the sun the moon casts a shadow on the earth. –B. __________________ – when the Earth is between the sun and the moon –C. For an eclipse to take place the moon’s orbit must cross the plane of the ecliptic when in the new or full moon phase.

22.3 Earth’s Moon VI. Moon facts –A. The only natural satellite of the Earth –B. Diameter is ____________________ –C. Diameter is ______that of the Earth –D. Our information comes from the ______________________ missions between 1969 and 1972 –E. On moon the force of gravity is only _________ that of Earth’s.

22.3 Earth’s Moon VII. The Lunar Surface –A. ________________ – mostly from rapidly moving debris or meteorites It is heavily cratered Pg. 631, figure 19 Rays – the material ejected from a crater –Surrounds the crater –B. ______________________ – densely pitted, light colored areas Mountain ranges

22.3 Earth’s Moon –C. _______________ – beds of basaltic lava Dark, relatively smooth areas Occurred when asteroids punctured lunar surface allowing lava to “bleed” out. –Rilles – long channels »Ancient lava flows –D. ____________________ – soil-like layer covering the lunar surface

22.3 Earth’s Moon VIII. Lunar History –A. Believed to have been formed when a Mars-sized object struck the Earth, ejecting a huge amount of crust and mantle rock, which eventually formed the moon. Known as the _______________________ ________________________________.