Planetary Science Flashcards
What is 1 Au?
The distance between the Earth and the Sun.
A measurement used for distances in our Solar System.
What is the order of body types in our System?
Sun, Rock planets, Asteroid belt, Gas Giants, Kuiper belt, Heliopause, Oort Cloud
Solar System Formation: The Sun
Molecular clouds reach a certain mass, nuclear fusion begins, a star is born, and the remains of the cloud form a proto-solar disk.
Our sun is heavy metal rich (likely second generation - metals form in previous star)
Solar System Formation: Gas Giants
These form first - Jupiter, Saturn, Uranus, Neptune
Form directly from the gas leftover after the sun is formed
Solar System Formation: Inner SS
Small rock bodies (asteroids) formed in Inner SS.
Temperature too high close to sun for volatile elements to condense.
The Grand Tack model of planetary migration and formation
1. Jupiter forms first, and is pulled towards the sun
2. Asteroids in its path are thrown off orbit, causing lots of asteroidal collisions. Some of these collisions cause larger planetesimals and planets form.
3. Saturn forms, and begins to pull Jupiter back to its present orbit
4. This causes lots of collisions in the Inner SS, forming the protoplanets and planetesimals
How do meteorites get to Earth?
Impacts on planetary bodies cause material to be blasted into space.
Some of this material can make its way to earth.
It is easier to find meteorites in certain places on earth and are well preserved (i.e. Antarctica).
Meteorites that are seen to fall are most valuable as they are least altered by earths processes.
What are the types of Meteorites?
Presolar grains - undifferentiated, preserved in asteroidal meteorites
Lunar, Mars, and Vesta (HEDs) meteorites - from differentiated planets (core, mantle, crust)
Carbonaceous Chondrites - C-type asteroid parent body
Ordinary Chondrite - S-type asteroid parent body
Primitive achondrites - partially melted asteroidal samples
HED’s - protoplanet Vesta
How are meteorite sub-types determined?
As with all rocks - texture, mineralogy, chemistry, and age
3-oxygen isotope ratio is the determining factor
How do we know where sub-types are from?
Measuring atmospheric gasses trapped in meteorites
Spectral mapping of the extra-terrestrial bodies allows for comparisons too
What are Chondrites?
Stony and Primitive (not melted or differentiated) Meteorite
Complex Rocks
- Solar nebula accretion
- Thermal and aqueous alteration
- Primary mineralogy preserves affects of pre-accretionary processes in in proto-planetary disk
Oldest rocks in solar system
Contain Chondrules
What are the three components of Chondrites?
1) Chondrules
2) Matrix
3) Ca-Al Rich Inclusion
What are the four ways to classify Chonrites?
1) Physical and Chemical differences
2) Petrologic Type
- How metamorphosed (heat or fluid)
3) Shock Stage
- Effects of asteroid collisions
4) Terrestrial Weathering
- What as earth done to it?
What are the types of Chondrites?
Ordinary (S-Type), Carbonaceous (C-type), Enstatite, R, and K
How do you distinguish differences in Chondrite types?
Mineralogy
Chondrule size and abundance
Oxygen isotopes
What’s the difference between S and C type Chondrites?
S-type:
- >85% of meteorites
- Very little carbon
- More chondrules (60-80%)
- Few refractory inclusion
- Lighter colour
- Coarse
- Water poor
C-type:
- <5% of meteorites
- Up to 5% carbon
- Less chondrules (<60%)
- Abundant refractory inclusions
- Darker colour
- Fine grained
- Water rich
