Cycles of the Sun, Earth and Moon

Flashcards covering the definitions of celestial rotations, specific periods for Earth and Moon cycles, and the mechanics of lunar phases and eclipses.

Axial Rotation

A rotation where an object rotates along an axis that passes through the object, commonly referred to as spinning.

Orbital Rotation

Often referred to as Revolution, this is when an object moves in a circular or curving path through space around another object.

Period

The amount of time required to complete one full rotation.

Earth's Orbital Period

The duration of one full orbital rotation for Earth, which is $365.25$ days.

Earth's Axial Period

The duration of one full axial rotation for Earth, which is $24h$.

Moon's Orbital Period

The duration of one full orbital rotation for the Moon, which is $27.3$ days.

S-E-M Diagram

A Sun-Earth-Moon System Diagram that shows the positions of these three objects at one moment in time, though not in correct proportion for size or distance.

Rotation Direction

When viewed from above, Earth's axial rotation, Earth's orbital rotation, and the Moon's orbital rotation all move Counterclockwise.

Phases of the Moon

The changing patterns of the Moon's surface illuminated by the Sun as seen from Earth, which follow a $29.5$ day cycle.

Full Moon

A phase where the Moon appears completely lit up to an observer on Earth.

New Moon

A phase where the Moon appears dark, though it remains visible due to light reflected from Earth to the Moon.

Eclipse

An event that occurs when one object blocks the direct light of another object.

Solar Eclipse

An event that occurs when the Moon blocks the light of the Sun, preventing direct sunlight from reaching part of Earth.

Lunar Eclipse

An event that occurs when Earth blocks light from the Sun, preventing direct sunlight from reaching the Moon.

Inclination of the Moon's Orbit

An important feature of the Moon's path around Earth that explains why eclipses do not occur during every full or new moon.