Earth and the Universe: From Geocentric to Heliocentric

Geocentric Model

Earth-centered model of the universe proposed by Ptolemy.

Ptolemaic Model

Structured geocentric theory from the 2nd century CE.

Heliocentric Model

Sun-centered solar system model proposed by Copernicus.

Big Bang

Event marking the universe's origin and expansion.

Light Year

Distance light travels in one year, about 5.88 trillion miles.

Parallax

Apparent shift in star position used for distance measurement.

Parsec

Distance where parallax angle is one arcsecond, ~3.26 light years.

Electromagnetic Spectrum

Range of electromagnetic waves, categorized by wavelength.

Wavelength

Distance between consecutive wave peaks, affects frequency.

Frequency

Number of wave cycles per second, measured in hertz (Hz).

Dark Energy

Unknown form of energy driving universe's accelerated expansion.

Dark Matter

Invisible matter making up most of the universe's mass.

Normal Matter

Ordinary matter forming stars, planets, and living beings.

Nuclear Fusion

Process powering stars, fusing hydrogen into helium.

Hertzsprung-Russell Diagram

Graph plotting stars by luminosity and temperature.

Solar Fusion

Energy generation in the Sun's core through fusion.

Photosphere

Visible surface layer of the Sun, emits light.

Corona

Sun's outer atmosphere, visible during solar eclipses.

Oceanic Trenches

Deep ocean floor depressions formed at subduction zones.

Plate Tectonics

Theory explaining Earth's lithosphere's movement and interactions.

Paleomagnetism

Study of Earth's ancient magnetic field recorded in rocks.

Continental Drift

Theory proposing continents move across Earth's surface.

Seafloor Topography

Study of underwater landforms and geological features.

Tectonic Plates

Large slabs of Earth's lithosphere that move and interact.

Subduction Zones

Regions where one tectonic plate is forced beneath another.

Mineral Composition

Elements and compounds making up Earth's crust and mantle.