1C1 Formation of the Earth & Paleontology Flashcards
Explore the history of Earth's formation and evolution, including paleontology.
How old is the Earth and the solar system?
Approximately 4.6 billion years old.
What process caused the solar nebula to collapse and start forming the solar system?
A shockwave from the supernova explosion.
Where is our solar system located within the Milky Way Galaxy?
In the Orion Arm.
(or Orion Spur)
It is about 27,000 light-years from the galactic center.
What percentage of the solar nebula’s matter did the Sun consist of?
99%
The sun was the first object to form in the center of the solar nebula.
How was the Sun formed?
- It formed about 4.6 billion years ago from a cloud of gas and dust in space.
- This cloud collapsed under its own gravity, causing it to heat up and form a spinning disk.
- The center of this disk became hot and dense, eventually igniting nuclear fusion to create the Sun.
What happened to the remaining 1% of the solar nebula’s matter?
It combined to form other celestial bodies in the solar system.
What are planetesimals?
- Small, solid objects that formed in the early solar system.
- They are the building blocks of planets, created from dust and gas that clumped together.
They formed planets by colliding and snowballing over time.
What is the leading theory about the formation of Earth’s moon?
The Giant-Impact theory
Describe the Giant-Impact theory.
A Mars-sized planetesimal collided with early Earth, causing debris to form the moon.
What was the state of early Earth during the Hadean Eon?
- Extremely hot, geologically active, and largely molten, with frequent volcanic activity and a hostile environment.
- The surface was likely covered with oceans of magma, and the atmosphere was thick with volcanic gases.
How long did it take for Earth to reach its current size?
10-20 million years.
What is the core accretion model and what is the issue with it?
- A theory stating that planets formed from solid materials colliding and snowballing over time.
- Issue: It may take too long for gas giants to form this way.
What is the disk instability model?
A theory suggesting planets formed from clumps of both dust material and gases collapsing together.
How did volcanoes contribute to the formation of Earth’s atmosphere and oceans?
By releasing gases and water vapor during eruptions, which accumulated over time.
The process of releasing gases and water vapor is known as ‘outgassing’.
What is the “goldilocks zone”?
A region where a planet is at the right distance from its star to support liquid water.
What role did cyanobacteria play in Earth’s early atmosphere?
They were the first photosynthetic organisms that converted carbon dioxide and water into oxygen through photosynthesis.
How did Earth’s early land form?
From volcanic eruptions and tectonic plate movements creating mountains and islands.
What caused early Earth to stay hot during its formation?
Constant bombardment by comets and meteorites.
How did ancient seas form on Earth?
From condensed water vapor falling as rain and collecting on the surface.
What gases primarily composed Earth’s early atmosphere?
- hydrogen
- helium
- methane
- ammonia
- water vapor
It lacked free oxygen.
What are the two main theories about planet formation in our solar system?
- The core accretion model
- The disk instability model
What process caused the Earth to cool over time?
Reduction of meteorite bombardment and space’s cold environment.
What is the primary evidence needed to determine the correct theory of planet formation?
Observations and studies of other solar systems.
How long did it take for Earth to cool down enough to support liquid water?
Approximately 500 million years.
