origin of the oceans Flashcards
where were the atoms that make up earth and everything on it formed
in stars billions of years ago
what is the most abundant element in the universe
hydrogen
what is the second most abundant element in the universe
helium
what is the third most abundant element in the universe
oxygen
explain the role of stars in the creation and distribution of elements
- Stars change hydrogen -> helium and heavier elements – nuclear fusion
- When they die, they explode and distribute this everywhere (lots of oxygen created in this process)
what is a galaxy
rotating aggregation of stars, dust, gas and other stuff held together by gravity
- Our solar system orbits the Milky Way galaxy
what are stars
massive gas spheres that form in nebulae - Ours is the Sun
how long does it take for our solar system to orbit the milky way
230 million years
how many galaxies are there
~100 billion galaxies - ours is apart of a 54-member galaxy cluster
what is the condensation theory
explains the formation of stars and planetary systems, including our solar system, from a nebula (a large, diffuse cloud of gas and dust)
explain the condensation theory
- A spinning nebula shrinks under gravity, heats up, and forms a protostar
- Shrinking continues until ~10 million °C, triggering fusion: hydrogen converts into helium, forming a star
- Fusion creates heavier elements (up to carbon and oxygen)
- Larger stars burn faster and can produce elements up to iron
- When carbon and oxygen are consumed, the star swells into a red giant (dying phase)
- Eventually, it collapses and explodes in a supernova, lasting ~30 seconds
- Heavier elements like gold and mercury are formed during the explosion - A nearby supernova could wipe out life
explain how Supernovae contributed to Earth and ocean formation
- Shockwaves made solar nebula spin and deposited heavy atoms
- Planets (and us) are made of stardust, originating from stars
explain the formation of the solar system
- ~5 billion years ago: Protosun formed
- Planets formed from surrounding material via accretion (small particles clumping into larger ones)
- Larger clumps had stronger gravity, attracting more matter
- Outer planets (Jupiter, Saturn, Uranus, Neptune) formed first - methane and ammonia ices condensing in cold temperatures
- Inner planets formed near the protosun - high temperatures allowed only high-boiling-point materials (e.g., metals, rocky minerals) to solidify (e.g., Mercury is mostly iron)
what is accretion
small particles clumping into larger ones
explain the origin of the solar system
- Material Condensation:
- Beyond Mercury: Silicon, water, oxygen condensed; methane and ammonia condensed farther out.
- Earth: Located mid-range, composed of water, silicon-oxygen compounds, and metals - Accretion Phase:
- Lasted ~30-50 million years
- Protosun ignited fusion, creating solar wind that cleared excess particles, halting accretion
- Gas giants (e.g., Jupiter) may have lost atmospheres similar to Earth’s due to solar winds - Formation of Early Earth:
- Young Earth was chemically homogeneous
- Heat from asteroid impacts, gravitational compression, and radioactive decay partially melted Earth - Density Stratification:
- Gravity pulled heavy elements (iron, nickel) to the core, releasing energy
- Lighter materials rose, forming Earth’s crust
- Process lasted ~100 million years - Formation of Moon:
- ~4.6 billion years ago: Mars-sized body collided with Earth
- Metallic material merged with Earth’s core
- Rocky mantle debris formed a ring, which condensed into the Moon
explain the formation of earths first and second atmosphere
- First Atmosphere: Radiation from the young Sun stripped away Earth’s initial outer gases
- Second Atmosphere: Formed through outgassing of trapped gases, including water vapor, carbon dioxide, and nitrogen
- Volcanic outgassing persisted, releasing gases and contributing to the evolving atmosphere
explain the formation of the ocean
- Initially, temperatures were too hot, causing water vapor to evaporate repeatedly
- Over time, the surface cooled, allowing water to condense and form droplets
- Over ~20 million years, water collected on the surface, dissolving minerals from rocks -> formed salty ocean
explain the development of the second atmosphere and how
water vapor, nitrogen, and CO₂
- CO₂ dissolved in oceans -> form carbonic acid
- ~1.5 billion years later, photosynthesis produced oxygen -> Oxygen Revolution
- Oxygen initially oxidized dissolved minerals, then accumulated in the atmosphere
- Early oceans were hot, with constant rainfall - periods of drastic climate change have occurred since
what the right order of magnitude
- big bang: 13 billion years ago
- first galaxies form: 11 billion years ago
- solar nebula: 5.5 billion years ago
- earth form: 4.6 billion years ago
- ocean form: 4 billion years ago
- first fossil evidence of life: 3.5 billion years ago
- oxygen revolution: 2 billion years ago
where did life probably start
in the oceans
* all life depends on saline water within its cells to dissolve and transport chemicals -> Strong suggestion early life was in ocean
why is life as we know it inconceivable without large amounts of water
- Can retain heat
- Moderate temperature
- Dissolve chemicals
- Suspend nutrients and wastes
how is life formed
aggregations of basic carbon compounds - transported to earth through comets etc.
how did the early atmosphere allow for organic life
- thick atmosphere likely blocked harmful UV radiation, enabling organic molecule formation
- Today, the ozone layer + oxygen do this
whats biosynthesis
process of how life began -> still speculative
how could deep-sea hydrothermal vents may have played a role in the origin of life
- alkali hydrothermal vents mixed with more acidic ocean waters to create a proton gradient
- This gradient is very similar to the ways cells pump protons across their membranes to harness energy - suggests vents might have provided the conditions for the development of energy-harnessing systems in early life forms
water differences on other planets
we have liquid water - hard to have
- Jupiter has hundreds of times as much water, but as ice
- Europa, moon of Jupiter shows signs of significant liquid water
- Mars may have had an ocean a long time ago
