Lecture 2 - Week 1 - Origin of the Earth Flashcards
Describe Hubble’s Law in 6 words?
Objects in space are moving apart.
What is the evidence of objects moving apart?
Redshift
Hubble’s Law supports the Big Bang because…
If objects are moving apart, they
must have started together at a
single point.
Big Bang Nucleosynthesis is considered responsible for…
The creating of some forms of hydrogen, helium and some lithium.
Stellar Nucleosynthesis creates elements by…
The super heating of elements that makes up the star.
In Stellar Nucleosynthesis, combining nucleons of this gas [ __________ ] with other elements (carbon, oxygen, neon, etc.) = magnesium, silicon, sulphur, calcium, iron, etc.
Helium
_________ are stellar nurseries. Stars form by collapse of parts of an individual __________.
Nebulae. Nebula.
Basic nucleosynthesis is…
The creation of nuclei from existing nucleons
Galactic Nucleosynthesis is when…
Cosmic rays collide with heavier atoms and create new forms of matter (this occurred in the moments after the BB)
When did the big bang occur?
How long after did the first stars form?
When did our solar system form?
- Big bang: 13.8 billion years ago
- First stars formed 200-400 million years after the BB
- Our solar system forms 9 billion years after BB
How do stars form from nebulae?
- Clouds are very large, very cold, very dense
- Combination means that clumps tend to collapse under own weight (gravity)
- Clumps = cores where new stars are forming
- Collapse (shrink)> higher density> higher gravity> collapse> higher density….and so on
- Eventually core ignites
What is an a accretionary disk?
A rotating disk of matter formed by accretion around a massive body due to gravity.
What are two formations in intermediary stage between the accretionary disk and the formation of a solar system?
The core of the disk becomes a protostar. Around the protostar is a disk of dust, gas, and other elemental matter known as a protoplanetary disk.
The matter in the ____________ sticks to each other to form clumps known as ____________.
Protoplanetary disk. Planetismals.
Eventually, after planetismals keep accreting material due to gravity, they become ____________.
Protoplanets.
Once they become large enough, the protoplanets become full-fledged ________.
Planets.
When the Earth became a planet, the heat from meteor bombardment caused it to melt. The liquified elements allowed…
Heavier elements to shift towards the center. And lighter elements to shift towards the surface.
The characteristics of the Earth’s physical layers are determined by heat and pressure… Therefore, the core is _______ and made of ______, even though it is very hot.
Solid. Metal: Iron.
What is the outer core made of?
Molten. Metal: Liquid iron and nickel.
What is the mesosphere?
Hot, solid, rock. Too much pressure for liquid rock to form.
What are the two characteristics of asthenosphere (upper mantle)?
Weak and plastic.
What is lithosphere (uppermost mantle and crust)?
Strong and rigid.
How old is Earth believed to be?
4.6 Billion
How old are the oldest rocks on Earth?
4.031 Billion years old
How old are the oldest minerals on Earth?
4.4 billion years old: zircons from a sandstone found in the Jack Hills of Australia
How do we know the Earth is 4.6 billion years old
when no rocks and minerals on our planet are older
than 4.4 billion years old?
Radiometric dates derived from meteorites during the Late Heavy Bombardment
When did the Late Heavy Bombardment end?
Aprox. 3.9 BYA
