Lecture 5 Flashcards
(26 cards)
What is a meteorite?
Fragments of rock from interplanetary space which entered in collision with a planet
Where do meteorites come from?
Asteroid collisions
What are the 3 subdivisions of meteorites?
Chondrites, Iron, and Stony-Iron
What are chondrules?
Quasi-spherical structures which indicate solidification from molten droplets splashed during collisions between various celestial bodies.
What are chondritic meteorites?
The most frequent ones, silicate dominated.
What are iron meteorites?
Meteorites which present large sized crystals-indicating a longer time of solidification.
What are stony-iron meteorites?
Silicates and iron-nickel alloys occur in approximately equal proportions-RAREST
What are the 3 categories of silicate dominated (chondritic) meteories?
Achondritic-do not have chondrites
Carbonaceous chondrites- have organic matter that make it shiny
Chondrites
What is special about carbonaceous chondrites?
They have amino acids as organic matter (not the same amino acids as ones that are the building blocks of life).
Why did dating of meteorites prove to be perplexing?
Because they are around 4.6 billion years old, which is exactly the same age as the basalts from the moon.
What do the lines on Phobos represent?
Parts of mantle of old celestial bodies that broke apart
What are comets?
Celestial bodies consisting mostly of frozen gases. (CO2, NH3, CH4, CO, H2O).
What creates the tail on a comet?
Formation of gases that are still attached to the body of the comet, but rotating the opposite way.
What is space dust?
Small particles that can pass through the atmosphere. Exits in both interstellar and interplanetary space.
What makes the study of space dust so difficult?
It’s easily contaminated and we don’t know when it was contaminated
What is space dust made of?
C, Mg, Fe, and Ca-makes it solid
What is the name of the machine that can collect space dust for us to study?
Galileo
What was the most important finding from space dust?
It’s dominant oxygen isotope is O17, whereas the dominant isotopes on Earth are O16 and 18. Concludes that there could be life outside of our galaxy.
What is the Solar Nebula Theory?
Theory that was developed in the 2nd half of the 18th century, beginning as a mathematical model, that explains the formation of the solar system in 6 stages
What is Phase 1 of the solar nebula theory?
Contracting Cold Cloud. Huge cloud of gases and cosmic dust begins to contract (dominant process) and rotate slowly. Composition of this cloud was mostly H and He
What is Phase 2 of the Solar Nebula Theory?
Rotating and Heating Cloud: Rotation became dominant, cloud became lens shaped, discoidal, and rotated FASTER. Matter then started to concentrate and heat in the centre of the cloud.
What is Phase 3 of the Solar Nebula Theory?
Chaotic Swirling and Incipient Accretion: Small sized particlesof cloud aggregated to form larger (irregularly shaped) rock particles. Source for turbulent movements. Caused cloud to also be concentrated in the rings around it, not only in the centre
What is Phase 4 of the Solar Nebula Theory?
Formation of Protoplanets: Larger, but with reduced gravity. Matter started to collapse due to gravitational attraction, initiating process of gravitational differentiation (iron towards centre, silicate towards periphery).
What was the cause of the Protosun (phase 4)
Gravitationally controlled matter compression
