Chapter 25 – Earth’s Moon
Section 25.1 – Origin and Properties of the Moon
Astronomy - The study of the universe
Origin of the moon –
•A planet-sized object impacted/collided with Earth
•Moon is made of same materials as Earth’s Crust
•Moon has a core – more dense materials at the core, less dense materials on the surface
Moon’s Surface –
•Meteoroids(icy/rocky fragments in space) impacted the moon, leaving craters
•Craters are depressions in Moon’s Surface
The moon today –
•Most all impacts are from micrometeoroids (very, very small) about the size of a sand grain
Moon’s Structure –
•Iron Core, partially molten area around the core, surrounds by a solid region and a crust
•Density is 3.3g/cm3whereas Earth is 5.5g/cm3. Therefore, the moon formed from mostly crust materials from Earth
Moon Properties –
•We only see the front side of the moon
•The moon rotates on its axis at the same period that it make one complete orbit/revolution around the Earth
Features of the Moon –
•Maria - dark areas (latin for Sea) Not water but actually dark basalt rock
•Rille- Trench-like valleys
•Lunar (moon) highlands - Areas of Lighter colored rock - breccia
•Regolith - Lunar soil
Space Exploration:
The first country to successfully send a MANNED mission to the moon wasthe United States.
The name of the mission was Apollo 11.
Neil Armstrong was the first man to walk on the moon.
25.2 - The Moon’s Motions
Moon’s motions –
•The moon rises in the east and sets in the west
•Rising and setting of the sun is a result of Earth’s rotation
•Moon’s orbit takes 27 1/3 days
When do we see the moon?
•When the moon is on the other side of Earth opposite the Sun, we see it at night
•When the Moon is in between the Sun and Earth, it is seen in the daytime sky
Moon’s orbit –
•Elliptical
•Perigee – when Moon is closest to Earth
•Apogee – when the moon is farthest from Earth in its orbit
Moon’s phases –daily changes in the moon’s appearance,why? 2 reasons:
–Moon reflects sunlight
–Moon is in orbit around the earth
•Waxing - Moving from new moon to full moon
•Waning - Moving from full moon back to new moon
•Crescent - ¼ moon reflects sunlight
•Quarter - ½ moon reflects sunlight
•Gibbous – 3/4 moon reflects sunlight
Phases of the Moon as It Orbits Around Earth
Solar Eclipse –
Earth’s moon passes between the sun and Earth and the moon’s shadow hits Earth’s surface.
Lunar Eclipse –
Earth’s shadow prevents sunlight from reaching the moon, Earth orbits between the sun and the moon.
Spring Tide - Extreme tides – very high and very low….double the pull
The sun, Earth and moon are aligned in a row.
Neap Tide - Not a lot of difference between high and low tides….not as noticeable.
The moon is perpendicular to Earth, the sun is in line with Earth.