Lecture 9 Flashcards
Why can each Jovian planet been considered a miniature solar system?
Its formation resembles that of the Sun
What are volatiles?
Chemicals that can be readily vaporised; these chemicals can be solid outside the frost line
What happened to the remaining volatiles after planet formation ceased?
They were blown away by a combination of photons and the solar wind
What does nebular theory say about the rotation of the sun?
It once rotated much faster than it does now
What are some possible reasons for planet rotation to be slowing?
-Friction between the solar and magnetic field
-Solar wind
Where are the short period comets located?
In the Kuiper belt (between Neptune and Pluto)
Where are the long period comets located?
In the Oort cloud
What special objects does the Oort cloud contain?
The Oort cloud contains primitive material that has not been touched by other objects in the solar system
What is the heavy bombardment period and what is some evidence that supports it?
A period where leftover planetesimals bombarded other objects in the later stages of the solar system formation
Evidence for this period is found in the cratering of planets and moons
What are some processes that cause planet resurfacing?
-Tectonics
-Magma
-Running water
What are the theories for the origins of the Earth’s water?
-Water was brought as icy planetesimals from comets (only about 10% of the Earth’s water may have come this way)
-Water was present at the time of formation (evidence: significant amounts of water stored in the Earth’s crust and mantle and ratios of heavy H2 and H2O)
What may some unusual moons be?
Captured planetesimals
How was the Earth’s Moon formed?
-Mars size planetesimal crashes into the young Earth, shattering everything
-The Earth is molten and rotating very rapidly
-Debris that splashed out from the Earth’s outer layers now orbits the Earth and eventually accretes to become the Moon
What strange planetary features can be explained by giant impacts?
-Axis tilt of Uranus
-Venus’ retrograde rotation
What are some of the types of exoplanets?
-Gas giants
-Super-Earth
-Neptune-like
-Terrestrial
What are two similar solar systems to ours?
-Kepler-90: contains 8 planets but with different compositions
-Trappist-1: similar sized planets to Earth with some having the potential for water
What is alpha decay?
Radioactive decay that releases a helium nucleus
What is beta decay?
Radioactive decay that releases an electron or positron
What is the main principle of radioactive dating?
All elements in a rock were formed at the same time and no new parent or daughter substituents were formed out of the radioactive decay process
This means that known half-lives can be used to figure out the age of a rock
What is an estimation for the age of the Earth?
4.54 +/- 0.05 billion years
What is an estimation for the age of the Solar System?
4.56 billion years
What does the Murchison meteorite show?
This 7 billion year old meteorite shows that some components of the solar system existed before becoming part of the solar nebula
