FORMATIONS: MOON, ATMOSPHERE, AND OCEAN Objective: I will describe the formation of Earth’s moon, atmosphere, and ocean. 12/2/15 PAGE 41

Formation of the Moon Giant Impact Hypothesis: a Mars-sized object collided with the moon pieces of the Earth’s mantle were thrown into orbit over time, the pieces clumped together to form the moon evidence: composition of Earth’s mantle is the same as the moon

Formation of the Oceans Two possible sources for Earth’s water: Volcanic Outgassing- early volcanic activity created steam, eventually forming into rain the rain gradually built up into oceans

Formation of the Oceans Water from Comets comets, which are made of ice, collided with early Earth at a high rate water from the comets melted into Earth’s atmosphere and formed rain which eventually formed oceans scientists have matched the composition of comet water to the water on Earth

Formation of the Atmosphere Earth’s early atmosphere was hydrogen and helium Earth’s gravity could not hold onto these light gases and they were blown away by the solar wind Outgassing- volcanic eruptions released carbon dioxide (CO 2 ), nitrogen (N 2 ), water vapor (H 2 O), methane (CH 4 ) and sulfur dioxide (SO 2 ) into the atmosphere

Formation of the Atmosphere Certain organisms, such as cyanobacteria, could survive in this atmosphere These organisms used the CO 2 during photosynthesis, releasing lots of oxygen into the atmosphere Current atmospheric composition: 78% N 2, 21% O 2, <1% CO 2, and trace gases