Moon Phases, Eclipses, and Tides

Vocabulary practice flashcards covering lunar surface features, orbital mechanics, lunar phases, solar and lunar eclipses, and tidal forces.

Moon

Any object that revolves around a planet.

Lunar Highlands

Mountainous regions found on the Moon's surface.

Maria

Smooth, dark regions on the Moon made from hardened lava produced by volcanic eruptions.

Moonquakes

Quakes and seismic tremors that occur on the Moon.

Moon's Illumination

The Moon does not produce its own light; it can only reflect light from the Sun like a mirror.

Synchronous Rotation

The condition where the Moon rotates on its axis and revolves around Earth at the exact same rate (about once every month, or $29\text{ days}$), causing observers on Earth to only ever see one side of the Moon.

Waxing Moon

The phase change where the Moon appears to be growing larger, identified by the light being situated on the right side.

Waning Moon

The phase change where the Moon appears to be shrinking or losing light, identified by the light being situated on the left side.

Crescent Moon

A Moon phase occurring when less than half of the visible Moon is illuminated, creating a distinct C-shape.

Gibbous Moon

A Moon phase occurring when more than half of the visible Moon is illuminated.

New Moon

The first phase of the lunar cycle (occurring around Day $1$) where the Moon is situated directly between the Earth and the Sun, appearing completely dark and unlit from Earth.

First Quarter Moon

The phase occurring around Day $7$ where the Moon is $\frac{1}{4}$ of the way through its cycle, appearing as a half moon with the illuminated side on the right.

Full Moon

The halfway point of the lunar cycle (around Day $15$) where Earth is between the Sun and the Moon, resulting in the Moon appearing fully illuminated.

Last Quarter Moon

The phase occurring around Day $22$ where the Moon is $\frac{3}{4}$ of the way through its cycle, appearing as a half moon with the illuminated side on the left.

Solar Eclipse

An astronomical event where the Moon passes directly between Earth and the Sun, blocking sunlight and casting a shadow on Earth; it occurs in the daytime exclusively during a new moon phase.

Lunar Eclipse

An astronomical event where Earth passes directly between the Sun and the Moon, casting a reddish shadow over the entire Moon (known as a blood moon); it occurs at nighttime exclusively during a full moon phase.

Tides

The daily rise and fall of Earth's waters on shorelines caused by the gravitational pull between the Earth, Moon, and Sun, producing two high and two low tides every $24\text{ hours and } 50\text{ minutes}$.

Spring Tides

Tides that occur twice a month when the Sun and Moon are aligned (during new moon and full moon phases), combining their gravitational forces to create the strongest pull on ocean waters.

Neap Tides

Tides that occur twice a month when the Sun and Moon are positioned at right angles to each other (during first quarter and last quarter phases), causing their gravitational forces to counteract and create the weakest pull on ocean waters.