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

28 Sep 2000ASTR103, GMU, Dr. Correll2 Earth 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?

28 Sep 2000ASTR103, GMU, Dr. Correll3 Earth and Moon 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

28 Sep 2000ASTR103, GMU, Dr. Correll4 Earth--Basic Facts

28 Sep 2000ASTR103, GMU, Dr. Correll5 Earth: 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 (CO 2 ), water (H 2 0), and nitrogen (N 2 ) from volcanic activity of hot, young Earth Formation of oceans, from extant water, and from water delivered by comets, began absorbing CO 2 –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)

28 Sep 2000ASTR103, GMU, Dr. Correll6 Earth’s Atmosphere Troposphere-- lowest level, where the weather happens Stratosphere-- important…where the ozone (O 3 ) resides –Ozone protects us from the Sun’s harmful Ultra- violet radiation Ozone--created by sunlight and O 2, destroyed by sunlight and certain industrial age pollutants

28 Sep 2000ASTR103, GMU, Dr. Correll7 Plate Tectonics Continents originally believed to be adjacent –Noticed by Newton, of course –1912, Alfred Wegener proposes continental drift theory “Pangea”

28 Sep 2000ASTR103, GMU, Dr. Correll8 Plate 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

28 Sep 2000ASTR103, GMU, Dr. Correll9 Earth’s Interior

28 Sep 2000ASTR103, GMU, Dr. Correll10 Earth’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

28 Sep 2000ASTR103, GMU, Dr. Correll11 Earth’s Magnetic Field

28 Sep 2000ASTR103, GMU, Dr. Correll12 Earth’s Magnetic Field The Northern Lights-- Aurora Borealis

28 Sep 2000ASTR103, GMU, Dr. Correll13 The Moon--Basic Facts

28 Sep 2000ASTR103, GMU, Dr. Correll14 Moon’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)

28 Sep 2000ASTR103, GMU, Dr. Correll15 Exploring the Moon Apollo 11--first lunar landing –Neil Armstrong--first person on the moon Apollo –all but one successfully returned from the moon with samples (moon rocks) –Apollo 13 made a good movie, though

28 Sep 2000ASTR103, GMU, Dr. Correll16 Moon’s Interior

28 Sep 2000ASTR103, GMU, Dr. Correll17 Origin 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

28 Sep 2000ASTR103, GMU, Dr. Correll18 Moon’s Origin

28 Sep 2000ASTR103, GMU, Dr. Correll19 Rotation 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

28 Sep 2000ASTR103, GMU, Dr. Correll20 Tides 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

28 Sep 2000ASTR103, GMU, Dr. Correll21 Moon’s orbit growing

28 Sep 2000ASTR103, GMU, Dr. Correll22 Earth and Moon 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

28 Sep 2000ASTR103, GMU, Dr. Correll23 Questions 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.