Ch. 22: “Origin of Modern Astronomy”

1. Ch. 22: “Origin of Modern Astronomy” 22.3: “Earth’s Moon”

2. The Lunar Surface • When Galileo first viewed the moon, he saw two different types of landscape-dark lowlands and bright highlands. • The dark regions resembled seas on Earth. • These were later named maria. • The moon has no atmosphere or water. • Since there is no atmosphere tiny particles from space continually bombard its surface & slowly smooth out the landscape. • The moon doesn’t have the weathering and erosion that continually change the surface of Earth. • Tectonic forces are not active on the moon.

3. There are many craters on the surface of the moon. These are round depressions in the surface of the moon. There are craters within craters on the moon. Most of them were produced by the impact of rapidly moving debris. Craters

4. Most of the surface of the moon is made up of highlands. These are light-colored areas that are densely pitted. Within these regions are mountain ranges. Highlands

5. The dark, relatively smooth area on the moon is called a mare. These are ancient beds of basaltic lava. The formed when asteroids punctured the lunar surface, letting magma bleed out. The lava flows are often over 30 meters thick. Long channels called rilles are associated with maria. Could possibly be the remains of ancient lava flows. Maria

6. All lunar terrains have a layer of gray debris that comes from a few billion years of bombardment from meteorites. This soil-like layer, called lunar regolith, is composed of igneous rocks, glass beads, and fine lunar dust. Regolith

7. The most widely accepted model of the origin of the moon is that when the solar system was forming, a body the size of Mars impacted Earth. The resulting debris was ejected into space, began orbiting around Earth, and eventually united to form the moon. Lunar History

8. Moon Facts • The moon is the Earth’s only satellite. It is about 238,900 miles away from Earth. • It takes one month for the moon to orbit around the Earth. The same side of the moon faces the Earth the whole time. • The diameter of the moon is 3475 km.

9. Moon Facts Cont. • There are different phases of the moon, but the moon does not really change its shape. The different shapes are from different amounts of light being reflected on the moon. The differences in the light depends on the position of the Earth, moon, and sun. ●The moon is about one quarter the size of Earth and it has about one-sixth of the Earth's gravity. It is made up of rock and dust. There is no air or life on the moon that we know of. There is no wind or weather on the moon. The footprints left there by the Apollo astronauts will remain there for many years because of this.

10. Astronaut Edwin Aldrin's footprint from Apollo 11 Apollo 16 photo of the Moon with some of the far side. Moon Facts Cont.

11. Moon Facts Cont. • The moon orbits Earth at an average speed of 2,288 miles per hour (3,683 kilometers per hour). • The Moon travels at different speeds during different parts of its orbit. It moves slowest when it is at its furthest distance from Earth. The Moon moves fastest in its orbit when it is closest to Earth.

12. Moon Facts Cont. • The moon causes many of the tides in the Earth's oceans. This is because of the gravity force between the Earth and Moon. • During full and new moons the gravitational forces of the Sun and Moon combine to produce the highest tides called Spring Tides. • During quarter moons the gravitational forces of the Sun and the Moon oppose each other to produce the lowest tides called Neap Tides.