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Lecture 7

HISTORY 2720 Lecture Notes - Lecture 7: Exoplanet, Solar Wind, Radial VelocityPremium

4 pages68 viewsSpring 2018

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Samuel White

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Molecules in space couldn't do much unless surrounding starsi.
Our solar systems started with a flattening disk that led to fusion.ii.
99% of the matter is the sun, the 1% is the rest of the solar systemiii.
Outer gassy planets contain 99% of the rest of the materialiv.
Accretion: material gathers together through collisions and materials orbiting then
forming together
Part 2A.
Contains great diversity of materials1.
Universe is getting more complex, diverse, and intersting2.
4th threshold: formation of earth and solar systemi.
Part 3B.
Big History Project: How did the Earth and Solar System form?I.
How did the Solar System Form?
Hist 2720: Big History
Originally proposed by Immanuel Kant and Pierre-Simon de Laplace two centuries ago
Interstellar gas and dust gathers and collapses under its own gravity
As it collapses, it gathers angular momentum, spins faster and flattens out
Planets gather in orbiting disk of dust (protoplanetary disk) around large central sun
Collapsing Cloud Model
No direct evidence, just a reasonable hypothesis
Why so little angular momentum in the sun?
Some initial problems…
Hard to see how else the sun could have captured planets
Captured objects would orbit in different planes and direction
Or why all the planets orbit in the same direction and same plane
…but no good alternatives
Asteroids and meteors as leftovers from early solar system, haven't gone through tectonics
that ruin the early structure
Composition of meteorites helps reveal process of accretion
New Evidence: Space Rocks
Same number of protons, different number of neutrons
Stable isotopes reveal provenance of matter - don't spontaneously decay over time; come
from same place/process
Radioactive isotopes reveal age through radiometric dating - decay at regular periods over
Solar system 4.55 billion years old
New Evidence: Isotopes
Determine composition of other planets, moons, and asteroids
Understand geology and change in Mars and Venus
New Evidence: Extraplanetary Missions (landers and space craft)
Dust clumps in pebbles shown through experiments
Planetesimals gather matter and become planets
But how do we get from pebbles to planetesimals?
New Evidence: Experiments and Models of Accretion
Lesson 7
Sunday, January 28, 2018 10:29 PM
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