Earth, Moon, and Sun

Gravity

The force that attracts two bodies towards each other, proportional to their masses and inversely proportional to the distance between their centers. It is responsible for keeping the planets in orbit around the Sun and the Moon in orbit around the Earth.

Rotation

The spinning of a celestial body on its axis, which causes the cycle of day and night.

Revolution

The motion of an object around another object in space, such as the Earth orbiting the Sun. It takes approximately one year for the Earth to complete one revolution.

Insolation

The amount of solar radiation received by a surface, typically measured in watts per square meter. Insolation affects weather patterns and climate.

Albedo

The measure of reflectivity of a surface, defined as the fraction of sunlight that is reflected back into space. Albedo influences climate and temperature by affecting the amount of energy absorbed by the Earth.

Solstice

The time during the year when the Sun reaches its highest or lowest point in the sky at noon, resulting in the longest and shortest days. This occurs twice a year, marking the start of summer and winter.

Equinox

The time when day and night are of approximately equal duration, occurring twice a year during spring and autumn. Equinoxes mark the change of seasons.

Spring Tide

A tidal phenomenon that occurs when the Sun, Earth, and Moon are aligned, resulting in higher high tides and lower low tides. Spring tides happen during full and new moons.

Neap Tide

A neap tide is a type of tide that occurs when the gravitational pull of the Moon and Sun are perpendicular to each other, resulting in the lowest tidal range. This phenomenon happens during the first and third quarters of the lunar phases.

Latitude

The angular distance of a point north or south of the Earth's equator, measured in degrees. Latitude affects climate and weather patterns.

Perigee

The point in the orbit of the Moon or a satellite where it is nearest to the Earth. Perigee affects the apparent size and gravitational pull of the Moon.

Apogee

The point in an orbit that is farthest from the celestial body being orbited, typically the Earth in the case of the Moon or satellites.

Waxing

Refers to the phase of the Moon when the illuminated portion increases, leading up to a full moon. This term describes the progression of the moon's light during its cycle.

Waning

The phase of the Moon where the visible portion of the illuminated surface decreases, occurring after a full moon.

Umbra

The darkest part of a shadow cast during an eclipse, where the sunlight is completely blocked.

Penumbra

The outer part of a shadow cast during an eclipse, where only a portion of sunlight is blocked, resulting in a partial shadow.