The Universe, Solar System, and Earth Systems

Vocabulary flashcards covering cosmological theories, universe models, solar-system formation hypotheses, and Earth’s major systems and layers.

Narrative of Genesis

Judeo-Christian cosmology stating God created the heavens and the Earth in six days and rested on the seventh.

Brahmanda (Cosmic Egg) Universe

Hindu Rigveda concept of a cyclic universe expanding from and collapsing into a single point called a Bindu.

Atomist Universe

5th-century B.C. Greek idea by Leucippus and Democritus that all matter is made of indivisible, indestructible atoms.

Organismic View of the Universe

Philosophy that galaxies, stars, planets, and life function like tissues of a single living cosmic organism.

Steady-State Infinite Universe

Descartes–Newton model proposing a uniformly distributed, eternally existing matter balanced by gravity.

Modified Steady-State Universe

Hoyle, Narlikar & Burbidge’s 1990s revision addressing flaws in the original steady-state theory.

Big Bang Theory

Lemaître’s idea that the universe began ~13.7 billion years ago from a hot, dense state and is still expanding.

Cosmic Inflation

Albrecht, Guth, Steinhardt & Linde’s proposal that the early universe expanded exponentially in fractions of a second after the Big Bang.

Geocentric Model

Ptolemaic system placing Earth at the universe’s center with celestial spheres orbiting it.

Heliocentric Model

Copernican-Galilean model positioning the Sun at the center with planets, including Earth, orbiting it.

Nebular Hypothesis

Kant-Laplace theory that a rotating gas nebula contracted into rings forming the Sun, planets, and satellites.

Planetesimal Hypothesis

Chamberlin & Moulton’s idea that a passing star drew solar material into orbit, coalescing into planets.

Tidal Hypothesis

Jeans & Jeffreys’ 1917 theory that near-collision tidal forces between the Sun and another star produced planets.

Protoplanet Theory

Kuiper & von Weizsäcker’s modification where turbulence broke a nebula into rotating gas whirlpools called protoplanets.

Cosmochemistry

Field founded by Harold Urey studying chemical processes in space; explains low-temperature formation of terrestrial planets.

System (Open)

A system that can gain or lose matter and energy to its surroundings.

System (Closed)

A system where matter remains constant; only energy crosses its boundary (e.g., Earth as a whole).

Solar Energy

Primary external energy source driving Earth’s atmospheric, hydrologic, and biological processes.

Lithosphere

Rigid outer layer of Earth encompassing the crust and uppermost mantle.

Atmosphere

Layered envelope of gases surrounding Earth, essential for weather, climate, and life support.

Hydrosphere

All of Earth’s water in liquid, solid, and vapor forms, including oceans, rivers, glaciers, and atmospheric moisture.

Biosphere

Sum of all ecosystems; regions of Earth where life exists—land, water, and atmosphere.

Mesosphere

Atmospheric layer where meteors burn up; sits above the stratosphere and below the thermosphere.

Stratosphere

Layer containing the ozone layer; airplanes fly here; absorbs harmful UV radiation.

Troposphere

Lowest atmospheric layer containing convection currents and most weather phenomena.

Thermosphere

Hottest atmospheric layer, split into ionosphere and exosphere; hosts satellites and radio wave propagation.

Hydrologic (Water) Cycle

Continuous movement of water among oceans, atmosphere, land, and biosphere, renewing freshwater supplies.

Condensation

Process where water vapor cools to form liquid droplets, leading to cloud formation.

Precipitation

Any form of water—rain, snow, sleet, hail—falling from clouds to Earth’s surface.

Evapotranspiration

Combined water loss to atmosphere by evaporation from land and transpiration from plants.

Surface Runoff

Water flow over land back to streams and oceans after precipitation.

Inner Core

Solid nickel-iron sphere about 2,440 km in radius at Earth’s center.

Outer Core

Liquid nickel-iron layer ~2,300 km thick surrounding the inner core; source of Earth’s magnetic field.

Mantle

Approximately 2,900 km-thick layer of magnesium- and iron-rich rock comprising 70 % of Earth’s volume.

Crust

Earth’s thin outer skin: ~8 km thick under oceans (oceanic) and ~32 km under continents (continental).

Bindu

The single concentrated point from which the Brahmanda (cosmic egg) universe expands and contracts.

Angular Momentum Conservation

Physical principle explaining why contracting nebulae spin faster and flatten into disks during solar-system formation.

Quasars

Extremely luminous, distant objects powered by supermassive black holes; cited in organismic universe discussions.

Earth Subsystem Interaction

Concept that lithosphere, atmosphere, hydrosphere, and biosphere continuously influence one another.

USGS Water Storage Diagram

Visualization by the U.S. Geological Survey mapping water cycle components like infiltration and groundwater storage.