Solar System Vocabulary and Big Ideas

Flashcards covering key astronomical vocabulary terms and big idea concepts regarding models of the solar system, planetary motion, eclipses, seasons, day/night cycles, and moon phases.

Geocentric model

The incorrect model of the solar system that states that the Earth is the center (believed by ancient astronomers like Aristotle and Ptolemy).

Heliocentric model

The correct model of the solar system that states that the Sun is the center of the solar system and all planets revolve around the Sun (developed and believed by astronomers like Copernicus and Galileo).

Gravity

The force of attraction, or pull, between any two objects.

Orbit

The path one object takes around another object.

Inertia

The tendency of a moving object to resist changes in motion.

Revolution

One complete trip of one object around another (Earth's revolution around the Sun takes 1 year; the moon's revolution around Earth takes 29.5 days).

Rotation

One complete spin on an axis (Earth's rotation takes about 24 hours).

Phase

The appearance of the shape of the Moon at a particular time.

Solar eclipse

The blocking of the Sun's light that happens when the moon passes directly between the Earth and Sun.

Lunar eclipse

The blocking of the Sun's light that occurs when the moon moves into Earth's shadow and is no longer reached by direct sunlight.

Earth's Seasons

Caused because the Earth is tilted on its axis as it revolves around the Sun; when a hemisphere is tilted towards the Sun, it receives more direct sunlight with longer and warmer daylight hours, and when tilted away, it receives less direct sunlight with shorter and colder daylight hours.

Day and Night

Occurs because the Earth spins (rotates) on its axis, taking ~24 hours to complete one spin; the side facing towards the Sun experiences daytime, and the side facing away experiences nighttime.

Moon Phase Cycle

The phenomenon where half of the moon is always lit up by the Sun, but we see different parts of the lit-up side as the moon revolves (orbits) around the Earth.

New moon

The phase of the moon where we only see the dark side from Earth.

Full moon

The phase of the moon where we see the illuminated side from Earth.