28 Sep 2000ASTR103, GMU, Dr. Correll1 Ch 05--Earth and Moon

28 Sep 2000 ASTR103, GMU, Dr. Correll 1

Ch 05--Earth and MoonCh 05--Earth and Moon


Earth and MoonEarth and Moon

• Will the ozone layer, which is now being depleted, naturally replenish itself?

• Who was the first person to walk on the Moon and on what Apollo space mission did this landing occur

• Do we see all parts of the Moon’s surface at some time throughout the lunar cycle of phases?

• Does the Moon rotate, and if so, how fast?• What causes the ocean tides?



• Earth’s Atmosphere• Plate Tectonics• Earth’s Interior• Earth’s Magnetic Field

• Moon’s surface• Humans exploring the moon• Moons origin• Moons causing tides on the earth


Earth--Basic FactsEarth--Basic Facts


Earth: Dynamic and Vital WorldEarth: Dynamic and Vital World

• Evolution of the Earth’s atmosphere– Initially, hydrogen and helium from the solar nebula

• Expelled after few 10’s of millions of years by Sun’s radiation

– 2nd generation, carbon dioxide (CO2), water (H20), and nitrogen (N2) from volcanic activity of hot, young Earth

• Formation of oceans, from extant water, and from water delivered by comets, began absorbing CO2

– Evolution of plant life in oceans began processing and transforming atmosphere--3rd generation

• carbon dioxide a component of seashells--limestone

• over billions of years, massive limestone bedrock form

• plants release oxygen which first caused oxidation of surface (rust!), but eventually stabilized at present levels

– 4 to 1 mixture of nitrogen to oxygen (with traces of other gases)


Earth’s AtmosphereEarth’s Atmosphere

• Troposphere--lowest level, where the weather happens

• Stratosphere--important…where the ozone (O3) resides– Ozone protects us

from the Sun’s harmful Ultra-violet radiation

• Ozone--created by sunlight and O2, destroyed by sunlight and certain industrial age pollutants


Plate TectonicsPlate Tectonics

• Continents originally believed to be adjacent– Noticed by Newton, of

course– 1912, Alfred Wegener

proposes continental drift theory

• “Pangea”


Plate TectonicsPlate Tectonics

• Where plates move apart, we see ridges– mid-atlantic ridge for

example

• Where plates press together we have mountain ranges and earthquake fault lines


Earth’s InteriorEarth’s Interior


Earth’s InteriorEarth’s Interior• During the formation of the Earth energy from

collisional accretion and nuclear fission (radioactive decay of uranium for example) heat the Earth led to planetary differentiation– heavier elements sank to the center (the core)– lighter elements rose to the surface (the mantle)

• Molten mantle still exists


Earth’s Magnetic FieldEarth’s Magnetic Field


Earth’s Magnetic FieldEarth’s Magnetic Field

• The Northern Lights--Aurora Borealis


The Moon--Basic FactsThe Moon--Basic Facts


Moon’s SurfaceMoon’s Surface

• Mostly volcanic in nature, but no longer active– basaltic rock

• Craters, mountains, and planes (mares) formed due to bombardment of solar system debris over billions of years

• Surface covered with a layer several inches deep of fine powder (regolith)


Exploring the MoonExploring the Moon

• Apollo 11--first lunar landing– Neil Armstrong--first

person on the moon

• Apollo 11-17– all but one successfully

returned from the moon with samples (moon rocks)

– Apollo 13 made a good movie, though


Moon’s InteriorMoon’s Interior


Origin of the MoonOrigin of the Moon

• Fission theory--moon separated from the Earth in the early era

• Capture theory--moon formed elsewhere in the solar system and was captured later in Earth’s gravity

• Collision ejection theory--moon formed from debris of collision between Earth and another body


Moon’s OriginMoon’s Origin


Rotation of the MoonRotation of the Moon

• Moon rotates synchronously with the Earth– one rotation of the Moon for

one revolution about the Earth

• Due to tidal forces--Earth’s gravity stronger on near side of moon than on far side– warping of moon’s molten

mantel when the moon was young dissipated rotational energy


Tides on the EarthTides on the Earth• Moon’s gravity causes Earth’s oceans to oblate (only a few feet). As the Earth rotates

through the bulges, the tides occur. A similar but weaker effect comes from the sun


Moon’s orbit growingMoon’s orbit growing



• Will the ozone layer, which is now being depleted, naturally replenish itself?– Yes, created naturally by sunlight

• Who was the first person to walk on the Moon and on what Apollo space mission did this landing occur– Neil Armstrong, Apollo 11, 1969

• Do we see all parts of the Moon’s surface at some time throughout the lunar cycle of phases?– No, synchronous rotation shows us only the near side

• Does the Moon rotate, and if so, how fast?– Once per revolution about the Earth

• What causes the ocean tides?– The Moon’s gravitational field oblating the oceans


Questions for thoughtQuestions for thought

• Describe the formation of the solar system, specifically address how this lead to the formation of the inner terrestrial planets and the outer gas giants. What additional processes happened on the Earth to create it’s interior, continents, oceans, and atmosphere.

Documents

28 Sep 2000ASTR103, GMU, Dr. Correll1 Ch 05--Earth and Moon