Earth and Space

A set of vocabulary flashcards covering key concepts related to Earth and Space, including terms related to astronomy, geology, and environmental science.

Rotation

Turning or spinning on an axis.

Revolution

The action of one object moving completely around another in an orbital path.

Axis

An imaginary line that runs through both poles of a planet.

Orbit

The path an object takes as it revolves around another object.

Equator

An imaginary line drawn around the earth that divides it into northern and southern hemispheres.

Northern Hemisphere

The half of Earth located above the equator.

Southern Hemisphere

The half of Earth located below the equator.

Summer Solstice

Marks the longest day of the year.

Winter Solstice

Marks the shortest day of the year.

Tide

The rising and falling of the ocean’s surface.

High Tide

Occurs when ocean water is at its highest level during the day.

Low Tide

Occurs when ocean water is at its lowest level during the day.

Spring Tide

A tide in which the difference between high and low tide is greatest.

Neap Tide

The least amount of difference between high and low tides.

Lunar Cycle

The appearance of phases of the Moon as viewed from Earth.

Waxing

An increasing amount of visible light on the moon’s surface.

Waning

A decreasing amount of visible light on the moon’s surface.

Galaxy

A huge system of millions or billions of stars, together with gas and dust held together by gravity.

Spiral Galaxy

A flat, disk-shaped galaxy with a central bulge and extending arms.

Elliptical Galaxy

The most abundant type of galaxy with a smooth, circular shape.

HR Diagram

A chart that graphs a star’s brightness and temperature.

Star

A huge burning sphere of gas fueled by nuclear fusion.

Nebula

A huge cloud of dust and gas in space held together by gravity.

Light Year

The distance light travels in one year.

Electromagnetic Spectrum

The entire range of electromagnetic waves from low frequency to high frequency.

Big Bang Theory

An explosion from an extremely small, dense, and hot bit of matter, widely accepted as the origin of the universe.

Gravity

The force that pulls all objects with mass toward one another.

Mass

The amount of matter in an object.

Weight

A measure of gravity exerted on an object.

Tectonic Plates

The broken sections of Earth’s crust.

Subduction

The process that occurs when one tectonic plate sinks beneath another plate because it is denser.

Continental Drift Theory

The hypothesis that all continents were formerly one landmass and have since drifted apart.

Aquifer

An underground layer of permeable rock, sediment, or soil that contains water.