Moons Features and Moons Features and PhasesPhases

Chapter 28Chapter 28

General InformationGeneral Information

Satellite: a body that orbits a larger body.Satellite: a body that orbits a larger body.

Seven planets in our solar system have Seven planets in our solar system have smaller bodies that orbit around them.smaller bodies that orbit around them.

Moons: natural satellitesMoons: natural satellites

Now, thousands of artificial satellites that Now, thousands of artificial satellites that orbit around earth-weather data, space orbit around earth-weather data, space telescopes, etc.telescopes, etc.

MareMare

MareMare : large, dark area of basalt on the : large, dark area of basalt on the moon; plains of dark, solidified lava. moon; plains of dark, solidified lava. (Maria)(Maria) Latin for “sea”Latin for “sea” Formed more than 3 billion years agoFormed more than 3 billion years ago

CratersCraters

Most of the surface of the moon is covered Most of the surface of the moon is covered with numerous bowl-shaped depressions, with numerous bowl-shaped depressions, called craters.called craters. Most formed from leftover debris from Most formed from leftover debris from

formation of solar system 4 billion years ago.formation of solar system 4 billion years ago.

Rilles and RidgesRilles and Ridges

Rilles : long, deep channels that run Rilles : long, deep channels that run through the maria.through the maria. Leftover lava channels from formation of Leftover lava channels from formation of

mariamaria

Ridges : long, narrow elevations of rock Ridges : long, narrow elevations of rock that rise out of the surface and criss-cross that rise out of the surface and criss-cross the mariathe maria

RegolithRegolith

Regolith : layer of gas and dust that covers Regolith : layer of gas and dust that covers most of the lunar surface.most of the lunar surface. Formed from the crushing of lunar rocks by Formed from the crushing of lunar rocks by

meteorites.meteorites.

Lunar RocksLunar Rocks

Similar to rocks on earthSimilar to rocks on earth

Contain many of same elements as earth Contain many of same elements as earth rocksrocks

Igneous-rock that forms when magma Igneous-rock that forms when magma coolscools

The three layers of the moonThe three layers of the moon

The side of the moon that always faces The side of the moon that always faces the Earth is called the NEAR SIDE. The the Earth is called the NEAR SIDE. The other side that faces away is called the other side that faces away is called the FAR SIDE.FAR SIDE.

Moon’s crustMoon’s crust on far side is thicker than on far side is thicker than that of near side due to pull of earth’s that of near side due to pull of earth’s gravity.gravity.

60-100 Km thick60-100 Km thick

Moon’s mantle and coreMoon’s mantle and core

Mantle : beneath the moon’s crust; made Mantle : beneath the moon’s crust; made of silica, magnesium, and iron.of silica, magnesium, and iron. Makes up more than half of the distance of Makes up more than half of the distance of

the moon’s diameterthe moon’s diameter

Core : small iron core that has radius less Core : small iron core that has radius less than 700 Km.than 700 Km. Thought neither to be completely solid or Thought neither to be completely solid or

completely liquidcompletely liquid explain why moon has explain why moon has almost no overall magnetic fieldalmost no overall magnetic field

The Giant Impact HypothesisThe Giant Impact Hypothesis

Began when large object, size of Mars, Began when large object, size of Mars, collided with Earth more than 4 billion collided with Earth more than 4 billion years ago.years ago.

Chunks of Earth’s mantle ejected into orbit Chunks of Earth’s mantle ejected into orbit around Earth. around Earth.

Debris eventually clumped together to Debris eventually clumped together to form moonform moon

Differentiation of Lunar InteriorDifferentiation of Lunar Interior

Early, lunar surface was covered by an Early, lunar surface was covered by an ocean of molten rock.ocean of molten rock.

Over time, densest materials moved Over time, densest materials moved toward the center of the moon and formed toward the center of the moon and formed small core and least dense materials small core and least dense materials formed the outer crust.formed the outer crust.

Meteorite BombardmentMeteorite Bombardment

Outer surface of the moon eventually Outer surface of the moon eventually cooled to form a thick, solid crust over the cooled to form a thick, solid crust over the molten interior.molten interior.Meteorite bombardment decreased Meteorite bombardment decreased significantly about 3 billion years ago and, significantly about 3 billion years ago and, thus, virtually ally geologic activity thus, virtually ally geologic activity stopped.stopped.This explains why the moon looks today This explains why the moon looks today almost exactly as it did 3 billion years ago.almost exactly as it did 3 billion years ago.

Phases & CyclingPhases & Cycling

The moon revolves around the Earth in The moon revolves around the Earth in 27.3 days27.3 days

It takes 29.5 days to go through a It takes 29.5 days to go through a complete cycle of phases. (New moon to complete cycle of phases. (New moon to new moon)new moon)

Lunar eclipse = Occurs when Earth is Lunar eclipse = Occurs when Earth is between the moon and the sun (earth’s between the moon and the sun (earth’s shadow)shadow)