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 _______________________

________________________________.