Earth, Moon, and Sun Relationships

Vocabulary flashcards summarizing Earth’s rotation, Moon phases, and the role of axial tilt in creating seasons.

Rotation

The 24-hour spin of Earth around its axis that causes day and night.

Axis

The imaginary line running through Earth from the North Pole to the South Pole about which Earth rotates.

Daytime

The period when a location on Earth faces the Sun and receives direct sunlight.

Nighttime

The period when a location on Earth is turned away from the Sun and receives no direct sunlight.

Moon Phases

The changing shapes of the Moon’s visible portion caused by its orbit around Earth and the way sunlight illuminates its surface.

New Moon

Phase when the Moon is between Earth and the Sun, and the lit side faces away from Earth, making the Moon appear dark.

Waxing Crescent

Phase following a new moon when a small, increasing sliver of the Moon’s lit side becomes visible.

First Quarter

Phase when half of the Moon’s near side is illuminated; occurs about one week after the new moon.

Waxing Gibbous

Phase between first quarter and full moon when more than half but not all of the visible side is lit.

Full Moon

Phase when the entire face of the Moon is illuminated as seen from Earth.

Waning Gibbous

Phase after a full moon when the illuminated portion begins to decrease but is still more than half.

Last Quarter (Third Quarter)

Phase when the opposite half of the Moon’s near side is lit compared to the first quarter.

Waning Crescent

Final phase before new moon when a decreasing sliver of the Moon’s lit side is visible.

Axial Tilt

Earth’s 23.5° tilt relative to its orbital plane, responsible for seasonal changes.

Seasons

Regular divisions of the year (spring, summer, autumn, winter) caused by Earth’s tilted axis and its orbit around the Sun.

Summer

Season when a hemisphere is tilted toward the Sun, receiving more direct sunlight and longer days.

Winter

Season when a hemisphere is tilted away from the Sun, receiving less direct sunlight and shorter, colder days.

Spring (Vernal Equinox)

Season beginning when both hemispheres receive nearly equal sunlight, marking the transition from winter to summer.

Autumn (Fall)

Season beginning when both hemispheres again receive nearly equal sunlight, marking the transition from summer to winter.