The Moon

1. The Moon Chapter 6

2. Characteristics of the Moon • The ___________ neighbor in space • No atmosphere • Marked with craters • The earth also has craters, but most have been erased by erosion and tectonic activity.

3. General Features • The Moon is 1/4th the size of Earth • 868.5 km diameter • 400,000 km away from the Earth • Craters – • Craters diameters on the moon range from centimeters to several hundred kilometers. Most craters on bodies such as the Moon are formed by the impact of solid bodies, such as asteroids. • See figure 6.13 for “Birth of the Moon”

4. Other Surface Features • _________ – Pronounced – A vast, smooth, dark, and congealed lava flow filling a basin on the Moon and on some planets. Maria often have roughly circular shapes. • Examples – Mare Serenitatis (Sea of Serenity), Mare Tranquillitatis (Sea of Tranquility) – site where astronauts first landed. • These “Seas” are not associated with water • Maria are believed to have formed in a relatively complex manner.

5. Maria formation • Maria were formed as the moon first formed. • As it cooled iron rich dense material sank into the interior, lighter material formed on the surface. • Large objects crashed into the surface and pushed large amounts of lunar crusts up, which formed mountains. • This allowed the release of molten material onto the lunar surface. It cooled relatively recently in lunar formation. • Most of the stellar debris that formed craters would have been attracted to the Earth because of it gravity and therefore remain smooth and unmarked with craters.

6. Lunar landscape • – Old, heavily cratered regions on the Moon. • – Long, narrow light colored markings on the moon or other bodies that radiate out from young craters. Rays are debris splashed out of craters by the impact that formed it. • Rilles -

7. Lunar Atmosphere • Most of the Earth’s atmosphere is a result of early volcanic eruptions and a large enough surface gravity to keep the gases close to the planet. • Two Reasons there is NO lunar atmosphere: • 1. • 2.

8. Lunar Rotation • The moon rotates on its axis, but it is equal to its orbital period. • This means that we always see the same side of the moon. • As the moon rotates, it is also orbiting around the earth. • rotation – The condition that a body’s rotation period is the same as its orbital period.

9. Eclipses • Eclipse – Occurs when one astronomical body casts its shadow on another. • eclipse – The passage of the moon between the sun so that our view of the sun is partially obscured. • eclipse – The passage of the Earth between the Sun and the Moon so that the Earth’s shadow falls on the Moon.

10. Schedule of upcoming Eclipses • Solar EclipsesLunar Eclipses • February 7, 2008 - February 21, 2008 • August 1, 2008 - August 16, 2008

13. Images of Lunar Eclipses

14. Tides • Caused by the gravitational pull of ________ on __________. • The pull is strongest on the side of the Earth that is __________ the moon. This pulls the water, creating a bulge near the equator. • The rotation of the Earth causes us to spin in and out of the higher water zones and in and out of low water zones. This occurs about every 6 hours along the coast. Giving us ___________ and ____________ tides. • Go over figures 6.20, 6.21, 6.22

15. Solar Tides • The Sun is much more massive than the moon, but it is at a much greater distance from the Earth. It does have an effect on the tides, but not to the intensity of the Moon. • ___________________ illustrate the effect of the sun on tides. Have nothing to do with spring, rather the observation of water “SPRINGING up the beach” • During spring tides the earth and moon are ________________ each other and enhance the gravitational pull causing a greater than normal tidal surge. Fig 6.23

16. Tidal Braking • If the day seems longer that is because it is! • Tidal braking – • The pull on the water gradually slows the rotation of the Earth. Thus, increasing the length of the day .002 seconds per century! • Newton’s 3rd law explains that just as the moon exerts a force on the water, the water also exerts a force on the moon. It is actually enough to push the moon ____ cm away from the earth each year. • This change is detectable by lasers.

17. Tidal braking • After billions of years of tidal braking, the Earth and the Moon will have ___________________. • This means only ________ of the planet will see the moon. • The effects of the moon on the tides also stabilizes our climate and __________________. • If we are still around when the Earth and moon’s rotations are synchronized, then we will really have some severe weather!

18. Phases of the Moon • The lunar cycle is a result of differing amounts of the moon’s surface being illuminated by the sun. It has ____________ to do with the Earth’s shadow! • The lunar cycle is approximately ________ days • The new moon occurs when the moon is in between Earth and the Sun: • A full moon occurs when the moon is on the opposite side of the Earth from the Sun: • See figure 1.13 and animations on the computer.

19. Phases of the Moon • – nothing to see • – Moon’s face begins to increase in size. • – The quarter away from the sun is lit. Appears to be half of the lunar face. • – Lunar face increasing __ illuminated • – Entire face illuminated • – Lunar face toward the sun lit. Illuminated surface is decreasing in size. (__ illuminated) • – Lunar face toward the sun is lit. Appears to be half of the lunar face. • – Side closest to the sun is illuminated, lunar face is increasing in size.