Lecture 3: Planet Formation Flashcards
What is the law of universality?
The belief that laws of nature apply to all parts of the universe, including earth.
What controls the formation of heavenly bodies in space?
- Gravity
- Magnitism
- Atomic forces
What is the currently accepted method that the solar system formed?
Solar Nebula Disk Model
What is a nebula?
A distinct region of intersetellar clouds composed of cosmic dust and gases - this is where stars are formed
What is a supernova?
A massive explosion at the end of a stars lifecycle.
Explain the solar nebula disk model.
A supernova releases massive wave of energy.
If this energy encounters a nebula, it will send a portion of the nebula spinning on an axis. As the nebula spins, it flattens into a disk shape. The spin creates a gravitational pull, pulling mass towards the centre of the disk. The mass concentrates over time and increased pressure causes temperature increases. With time, this forms a protostar. Eventually, the protostar atoms undergo fusion, creating a star. Planetesimals then start to form around the star through accretion. As the star becomes fully formed, it’s presence influences planet formation through its gravitational pull, solar winds, and its continued spin from the former nebula.
What are the rocky planets?
Mercury, Venus, Earth, Mars
What are the gas and ice planets?
Jupiter, Saturn, Uranus, Neptune
What is the frost line?
The distance where the sun’s heat is no longer enough to vaporize/melt water
Why are metal/rock planets close to the sun and gas/ice planets far?
Terrestrial planets formed close to the Sun where temperatures only rock/metal could condense. The gas/ice planets formed outside the frost line where temperatures were low enough for ice condensation.
What is the proof for the solar nebular disk model?
We observe dusty discs surrounding nearby young stars.
What is the proof for the supernova part of the solar nebular disk theory?
Fe-60 is only a byproduct of explosive supernovas and we observe it on the ocean floor.
How was the earth formed?
accretion of rocky materials
What are the layers of the earth & their composition?
Inner core: solid iron and nickel ball
Outer core: molten iron and nickel
Lower mantle: mainly of rock
Upper mantle: mainly rock
Crust: thin layer where life exists (100 km)
How do we know about the composition of the inner layers of the earth?
Determined by interpreting timing of seismic waves as energy passes through different types of matter.
How was the moon formed?
Protoplanet Theia collided with the earth and the earth’s gravitational field kept the debris from being lost. It ended up in orbit and became the moon
What were important process that helped life appear in the early days of earth?
Plate tectonics, magnetic fields, out gassing of cooling rocks
Why is earth unique for life?
- habitable distance from the sun for liquid water and gaseous CO2 –> water provides variety of physical terrains and is necessary for life
- planetary mass to retain atmosphere and ocean, large enough for a solid and molten core to generate a magnetic field
aka the goldilocks zone
How do plate tectonics influence life?
builds up landmass for varied terrains
enhances biotic diversity through ocean circulations, volcanic islands, glaciations, recycling of carbon in the carbon cycle
What is the Jupiter factor?
Jupiter deflects or captures many asteroids and comets, reducing the risk of impacts on other planets
What is the large moon factor?
The unusually large size of Earth’s moon relative to its planet, and the fact that it is a significant factor in the Earth’s stability and climate (ex: tidal zones)
What is accretion?
The accumulation of smaller objects into a massive object by gravitationally attracting more matter
What is a planetesimal?
A body with the potential to come together with others under gravitation to form a planet.
What are solar winds?
The continuous flow of charged particles from the sun which permeates the solar system.
