The History of the Earth

• what is the theory for how the universe formed?

  Big Bang theory
• what is the hypothesis for how the solar system formed?

  nebular hypothesis
• what is the hypothesis for how the earth formed?

  gravitational differentiation
• what is the hypothesis for how the moon formed?

  giant impact hypothesis
• when did the universe originate?

  13.7 billion years ago
• when did the solar system originate?

  4.5 billion years ago
• what is our solar system?

  the region of space which falls under the gravitational influence of our sun
• what is our solar system thought to have originated from?

  a spinning cloud of gas and dust
• what were the two main gases which comprised the spinning cloud thought to originate our solar system?

  hydrogen and helium
• what caused the core of the spinning cloud of gases which orientated our solar system to become hotter and denser?

  the force of gravity
• which process marked the birth of our sun?

  nuclear fusion
• what is accretion?

  when mutual gravity caused clusters of rocks to come together to form the planets
• which process was responsible for clusters of rocks coming together to form planets?

  accretion
• what are the four rocky planets?

  mercury, venus, earth and mars
• what are the four gas giants?

  Jupiter, saturn, uranus and neptune
• during which period of time was the Earth fully molten?

  Hell eon
• what are the two types of differentiation?

  planetary and gravitational
• what is planetary differentiation?

  chemical elements of a planetary body separated due to their physical and chemical behaviours
• what is planetary differentiation mediated by?

  partial melting
• what is gravitational separation?

  separation due to density
• what does felsic mean?

  silicate minerals, magma or rocks which are enriched in lighter elements and have a high silicate content
• give three examples of lighter elements?

  sillicon, oxygen and sodium
• what does ultramafic mean?

  igneous rock with extremely low silica composition
• name the planetary body believed to have collided with the Earth?

  Theia
• how long ago was the great oxidation event?

  2.4 billion years ago
• what happened during the great oxidation event?

  oxygen reacted with methane and removed it
• why did the great oxidation event lead to global glaciation?

  the methane was keeping earth warm enough to have liquid water on it
• what did the great oxidation event lead to?

  global glaciation and a 'snowball earth'
• what is the mechanism responsible for earth's magnetic field called?

  geodynamo
• what causes the geodynamo?

  convection and conduction currents in the fluid core
• what is the process by which two light atomic nuclei combine to form a single heavier one?

  nuclear fusion
• what is the process by which a neutron slams into a larger atom, forcing it to split into two smaller atoms?

  nuclear fission