Dsst Astronomy (Part 4): Eclipses And Moon Phases

Front 1

The darkening of one celestial body as it enters the shadow of another is called an ____________.

Back 1

Eclipse. An eclipse occurs when one body is obscured by another.

Front 2

A _______ eclipse occurs when the moon moves between the Earth and the Sun.

Back 2

Solar. Although the moon is much smaller than the Sun, its proximity to Earth makes our satellite's apparent size nearly that of the Sun.

Front 3

Solar eclipse come in four varieties: ______, annualar, partial, and hybrid.

Back 3

Total. In a total eclipse, the sun is completely obscured by the moon. The corona is still visible around the moon.

Front 4

An annular eclipse differs from a total eclipse due to the _______ of the moon.

Back 4

Apparent size. In this instance, the sun appears as an annualar ring around the silhouette of the moon.

Front 5

Hybrid eclipses, intermediary between total and annular eclipses, are _______.

Back 5

Rare. At some points on Earth, hybrid eclipses appear total and at others they appear annular.

Front 6

A partial eclipse occurs when the moon only _______ obscures the Sun.

Back 6

Partially. When only part of the moon enters the umbra, a partial eclipse occurs.

Front 7

A _______ eclipse occurs when the Earth moves between the moon and the Sun.

Back 7

Lunar. There is always a Full Moon on the evening of a lunar eclipse.

Front 8

Earth's shadow can be divided into _____ distinctive parts.

Back 8

Two. These are called the umbra and penumbra.

Front 9

The darkest part of Earth's shadow is the _______.

Back 9

Umbra. There is no direct solar illumination within the umbra.

Front 10

The __________ of Earth's shadow is responsible for partial eclipses.

Back 10

Penumbra. The penumbra is the part of the shadow surrounding the umbra.

Front 11

Observers on Earth ______ see the far side of the moon.

Back 11

Cannot. Because the moon's rate of revolution and rotation match ours, we always see the same side of the moon.

Front 12

The moon's gravity is ____ ours.

Back 12

One-sixth. An object weighing 120 pounds on Earth would measure 20 pounds on the moon.

Front 13

The moon's atmosphere is ______.

Back 13

Negligble. Because the moon has so little atmosphere, temperatures vary more than 100 degrees between lunar day and night.

Front 14

The dark, flat regions of the moon's surface are the ___________.

Back 14

Lunar Maria. These low, dry areas were flooded with molten material billions of years ago.

Front 15

________ are caused by the impacts of meteoroids.

Back 15

Craters. The moon's largest crater, the 2,240-kilometer-diameter South Pole-Atikin Basin, is also the largest known crater in the Solar System.

Front 16

The point of the moon's orbit that brings it closest to Earth is its _____________.

Back 16

Perigree. The closest point in an object's orbit of Earth is its perigree.

Front 17

The point of the moon's orbit where it is farthest from the Earth is its _____________.

Back 17

Apogee. The farthest point in an object's orbit of Earth is its apogee.

Front 18

The moon's earthly orbit is _____ days long.

Back 18

29.5. Although our year has a solar basis, our months follow the lunar calendar.

Front 19

The changes in appearance during the moon's orbit are called its _______.

Back 19

Phases. The moon has seven phases: New Moon, First Quarter, Gibbous Moon, Full Moon, Waning Moon, and Third Quarter.

Front 20

When the moon appears completely dark from Earth, it is in its _________ phase.

Back 20

New. The moon appears dark because it is between the Earth and Sun.

Front 21

When the illumination of the moon increases, it is _________.

Back 21

Waxing. A Waxing Moon phase is the intemediary phase between New and First Quarter.

Front 22

The First Quarter represents the moon phase _____ between New and Full.

Back 22

Halfway. The First Quarter moon occurs at the halfway point of the moon's increase in illumination.

Front 23

The not-quite-full moon is a ________ moon.

Back 23

Gibbous. The Gibbous Moon phase is the period between Quarter and Full as the moon's illumination increases.

Front 24

A completely illuminated moon is said to be _____.

Back 24

Full. The Full Moon occurs when the side facing the earth is completely illuminated.

Front 25

As the moon's illumination begins to decrease, it is said to _____.

Back 25

Wane. A Waning Moon describes the period when the visible lighted area of the moon grows smaller.

Front 26

The moon phase between Full and New is called the ________.

Back 26

Third Quarter.

Front 27

The line separating night and day is the ____________.

Back 27

Terminator. This line separates the parts of a body experiencing day from the parts experiencing night.

Front 28

In July _____, the first humans walked on the moon.

Back 28

1969. Neil Armstrong and Buzz Aldrin set foot on the moon on July 20, 1969.

Front 29

The rise and fall of an ocean's surface is the ________.

Back 29

Tide. The changing tide is influenced by the positions of the Sun and Moon, the rotation of the earth, and the shape of the local sea floor.

Front 30

The moon's ________ is a major influence on Earth's tides.

Back 30

Gravity. The pull of the moon's gravity effectively stretches the earth's oceans into an ellipse with Earth at the center.

Front 31

______ Tides are the twice-monthly higher-than-usual high tides.

Back 31

Spring. These extra high tides occur when the Sun, Moon, and Earth are in alignment.

Front 32

Tides with the greatest difference between high and low tide are called _______ Tides.

Back 32

Spring. Low tide generally falls at a relatively constant level, but high tide is variable.

Front 33

Tides with the least difference between high and low tide are called _______ Tides.

Back 33

Neap. Neap Tides occur twice each month when the Sun and Moon are at Right angles to the earth.

Front 34

The two lowest tides in a month are the ______ Tides.

Back 34

Neap. Lower-than-usual tides are Neap Tides.

Front 35

Most planetary orbits take the form of an __________.

Back 35

Ellipse. The planets of our solar system orbit our star in elongated - not perfect - circles.

Front 36

_________ is the attractive force between two objects.

Back 36

Gravity. The magnitude of this attraction depends on the masses of the involved objects and the distance between them.

Front 37

The tendency of an object to stay in motion or remain at rest is called _________.

Back 37

Inertia. This Newtonian principle means that a moving object will tend to continue in a straight line and a stationary object will tend to remain in place.