Origin of the Universe, Earth, and Early Life

Vocabulary practice flashcards covering cosmic formation, planetary accretion, Earth's layers, hypotheses on the origin of life, and marine ocean zonation based on lecture notes.

Big Bang

The event approximately $13.7$ billion years ago in which the universe, starting as a concentrated single point containing all known matter and energy, began to expand.

Supernova

A massive stellar explosion that can occur at the end of a star's theorized life cycle.

Nebula

A large cloud of hydrogen and helium from which the solar system and planets orbiting the Sun originally formed.

Nebular Theory

The model proposing that gases revolving around the Sun condensed into masses too small to become stars, resulting in planets that formed through accretion.

Accretion

The process through which Earth and other solar system planets accumulated matter and formed, according to the nebular theory.

Density Stratification

The process during Earth's molten phase where heavier matter (iron and nickel) sank toward the center while lighter matter (oxygen and silicon) floated toward the surface, establishing Earth's layered structure.

Four Layers of the Earth

The structural layers of the Earth from the center outward: Inner core, Outer core, Mantle, and Crust.

Orpheus Theory

The most widely accepted theory for the Moon's origin, stating that a planet-sized body struck Earth during its early development and ejected material into orbit that aggregated into the Moon.

Outgassing

The release of volcanic gases that occurred once the Earth cooled enough to solidify a crust, forming the early atmosphere.

Abiogenesis

The formation of living organisms from nonliving matter, sometimes referred to as spontaneous generation.

Cyanobacteria

The oldest known marine fossil evidence of life, dating back approximately $3.5$ billion years.

Urey-Miller Experiment (1953)

A laboratory study conducted in $1953$ that did not create life itself, but demonstrated that basic organic molecules utilized by living systems could form under prebiotic conditions.

Primordial Soup Hypothesis

A hypothesis proposing that Earth's initial life arose from organic compounds accumulated in the early oceans.

Pelagic Zone

The open water column portion of the ocean, which is horizontally categorized into the neritic zone and the oceanic zone.

Neritic Zone

The coastal ocean water region extending from the low-tide mark to the edge of the continental shelf.

Oceanic Zone

The open water area of the ocean situated beyond the edge of the neritic zone.