Earth As a Planet - Vocabulary Flashcards

Vocabulary flashcards covering key terms from Unit 1, Chapter 1: Earth as a Planet, its shape, the solar system, atmosphere, biosphere, hydrosphere, cycles, and related concepts.

What is Earth as a planet?

The third planet from the Sun; a spherical oblate spheroid that supports life, with about 70% of its surface covered by water.

What is the Solar System?

The Sun and all bodies that orbit it, including planets, moons, asteroids, comets, and meteoroids.

What is an Oblate Spheroid?

A sphere that is flattened at the poles and bulges at the equator due to rotation.

What is a Geoid?

The Earth-shaped figure that approximates mean sea level and accounts for irregularities in Earth's shape.

What is Earth’s Equatorial Diameter?

Earth’s diameter through the equator: $12,756$ km.

What is Earth’s Polar Diameter?

Earth’s diameter through the poles: $12,714$ km.

What did the Bedford Level Experiment show?

An experiment showing curvature of the Earth by observing a middle pole appearing higher from an end of a canal.

How does the Sighting of a ship prove Earth's curvature?

Observation that a distant ship’s hull appears hull-first due to curvature, indicating a curved surface.

What is the Pole Star (Polaris) and what does its altitude indicate?

A star near the North Celestial Pole; its altitude corresponds to the observer’s latitude ($90^ ext{o}$ at the North Pole, decreasing toward the equator).

How does a Lunar Eclipse provide evidence for Earth's shape?

Earth’s shadow on the Moon, typically seen as a circular arc, indicating Earth is larger than the Moon.

What does a Circular Horizon indicate?

From higher altitudes, the horizon appears circular; its width increases with altitude, evidencing a curved surface.

How do Satellite Pictures confirm Earth's shape?

Images from space that confirm Earth’s sphericity and polar flattening.

What is Circumnavigation and what does it prove?

Travel around the globe and return to the starting point, proving Earth’s roundness (e.g., Magellan’s voyage).

What is the Atmosphere?

The layer of air surrounding Earth, a mixture of gases including nitrogen, oxygen, carbon dioxide, and trace gases.

What is Nitrogen and its role in the atmosphere?

A major atmospheric gas ($\approx78\%$); essential nutrient; cycles through the biosphere.

What is Oxygen and its role in the atmosphere?

The second most abundant atmospheric gas ($\approx21\%$); used in respiration and produced by photosynthesis.

What is Carbon Dioxide and its role in the atmosphere?

A trace gas in the atmosphere essential for photosynthesis and a greenhouse effect contributor.

What is the Greenhouse Effect?

Natural trapping of heat by atmospheric gases that keeps Earth’s surface warmer than it would be otherwise.

What is Ozone and its importance?

Ozone layer in the stratosphere that absorbs harmful ultraviolet radiation from the Sun.

What is the Water Cycle?

Continuous movement of water among oceans, atmosphere, and land through evaporation, condensation, precipitation, and runoff.

What is the Hydrosphere?

All water on Earth: oceans, rivers, lakes, groundwater and other bodies.

What is the Lithosphere?

The rigid outer layer of Earth, including the crust and upper mantle.

What is the Biosphere?

The life-supporting zone where atmosphere, lithosphere, and hydrosphere interact to sustain life.

What is an Ecosystem?

A self-regulating, interdependent system of living organisms and their physical environment.

What is Photosynthesis?

Process by which green plants convert light energy, carbon dioxide, and water into glucose and oxygen.

What is the Carbon Cycle?

Movement of carbon among the atmosphere, organisms, soil, and oceans; includes fixation by photosynthesis and return by respiration, decomposition, and combustion.

What is the Nitrogen Cycle?

Movement of nitrogen through the atmosphere, soil, and living organisms; major reservoir in the atmosphere and involves nitrification and de-nitrification.

What is the Oxygen Cycle?

Cycle of oxygen through respiration and photosynthesis; oxygen produced by plants and returned to the atmosphere.

What is a Producer?

An autotroph that makes its own food via photosynthesis.

What is a Consumer?

An organism that feeds on other organisms (heterotroph).

What is a Decomposer?

An organism that breaks down dead matter (saprotroph).

What is an Autotroph?

An organism capable of synthesizing its own food from inorganic substances.

What is a Heterotroph?

An organism that cannot synthesize its own food and relies on consuming others.