The Universe & The Earth

The flashcards cover key concepts regarding the formation and structure of the Universe and Earth, including theories, processes, and compositions.

The prevailing theory for the beginning of the Universe is the __.

Big Bang Theory.

Georges Lemaître first proposed the Big Bang Theory in the __.

1920s.

The Universe began approximately __ years ago from a singularity.

13.7 billion.

During the inflation stage of the Big Bang, matter and energy experienced __.

rapid expansion.

The early stage when light couldn’t pass through freely due to dense particles is called __.

Opaque Universe.

The formation of atoms led to a __, allowing light to travel.

Transparent Universe.

The solar system formed from a rotating cloud of gas and dust called a __.

nebula.

Inner planets are mostly composed of silicates and metals, while outer planets are __.

gas or ice giants.

The Sun accounts for __% of the total mass of the solar system.

99.85%.

Pluto was reclassified as a __ in 2006 by the IAU.

dwarf planet.

Venus rotates in a __ direction, causing the Sun to rise in the west.

retrograde.

The three major processes through which Earth formed are Accretion, __, and Differentiation.

Heating.

The event where heavier elements sank to form Earth's core is known as the __.

Iron Catastrophe.

Computational models suggest that a Mars-sized planetesimal named __ collided with early Earth to form the Moon.

Theia.

The atmosphere formed in four stages, starting with the loss of the __ atmosphere to solar wind.

primordial.

Oxygen in Earth's atmosphere built up through photosynthesis by __ and plants.

cyanobacteria.

The lithosphere includes the crust and the __ mantle.

uppermost.

Increased pressure in the inner core forces atoms tightly together, preventing __ despite high temperature.

melting.

Isostasy explains why the continental crust __ higher than denser oceanic crust.

floats.

Eratosthenes estimated Earth's circumference at about __ km using geometric methods.

41,000.