Life on earth 2
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Why did Galileo believe the planets were moving?
When observing the faces of venus and jupiter through a telescope he noted that their appearances changed depending on when they were observed
How did the stars help our understanding of the elements?
- Huggins & Miller (1864)
- The sun and stars shame the same elements of earth
- This could mean life exists elsewhere
How are atoms formed using forces brought together?
- Quarks are brought together by electromagnetic forces, bringing protons and neutrons to the nucleus
- Gravity then merges these clouds of atoms together, increasing density and temperatures to fuse them in nuclear fusion
- After supernova a great deal of protons and neutrons can be fused in greater numbers to form heavier elements for a few minutes (such as uranium, which is why they're so rare)
- These clouds are again brought together by gravity, but they now contain rocks and heavy materials
- The matter at the core is fused but the rest of the matter orbits it if there isn't enough energy for fusion to occur, this is how planets are formed
How old is the solar system and how do we know this?
- 4566,000,000 years old
- Measure the decay of radioactive isotopes within meteorite samples, we always find the same age
Why do we have seasons?
- The earth and the moon collided
- This upset the earth's axis
- The gravity of the moon has a gyroscopic effect on the earth, keeping this axis stable
- The moon also controls the tides allowing for life to thrive in optimum conditions
How does the earth's atmosphere help to sustain life?
- There were many volcanic eruptions, releasing elements such as sulphur which were up-taken by electromagnetic storms and later became prokaryotes
- Miller & Urey (1959) added water, methane, ammonia and nitrogen to a seres of connected pipes and beakers and heated to evaporation to simulate an atmosphere
- 20 different amino acids were created, some not naturally occurring
Why is water essential to life?
- A key component of the atmosphere
- Facilitates plate tectonics which means dry land exists allowing for life to grow there
- Allows for plant life to grow
- Life develops in pockets of primordial soup due to habitable conditions in water
How do chloroplasts allow for life on earth?
- Occurred first in cyanobacteria
- Through the photosynthesis of energy from solar fusion to form oxygen molecules and carbohydrates
- Depleted the CO2 in the effect, retains the water in the oceans and prevents it from boiling and evaporating
- This process of terraforming took thousands of millions of years
How is earth's magnetic field essential to life?
- DNA molecules are fragile and cannot stand high levels of radiation without devastating amounts of radiation
- Protects us from this radiation
How is endosymbiosis essential for life on earth?
- The process by which prokaryotic cells merge to form eukaryotes with mitochondrion and other membrane bound organelles that are vestigial bacteria
- 1.5 thousand million years to develop
- These cells are capable of merging to form multicellular organisms
- Allowed for very basic life and plants do develop in the oceans 1000,000,000 years ago
What happened to 90% of early life on earth?
- It was made extinct due to an asteroid collision around 500,000,000 years ago
- This allowed the dinosaurs to evolve and thrive
- Until 64,000,000 years ago when an asteroid wiped out over 70% of life on earth
- This next tree of life is our own
What conditions are essential in order for life on earth to develop?
- Right distance from a star to allow for a hospitable environment
- Accidental cataclysmic collisions leading to the formation of water molecules, the moon at the right distance which allows tides to occur and pockets of primordial soup to form
- A stable polar axis for long term weather stability
- Hot interior for volcanic eruptions that allow bacteria to form
- Photosynthesising primitive life that produces an oxygen rich atmosphere allowing for conservation of water (that facilitates plate tectonics and the formation of dry land)
- Molten iron outer core to form an electromagnetic field protecting the planet from solar radiation
- Non biological extinction events
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