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37 Cards in this Set
- Front
- Back
The darkening of one celestial body as it enters the shadow of another is called an ____________.
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Eclipse. An eclipse occurs when one body is obscured by another.
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A _______ eclipse occurs when the moon moves between the Earth and the Sun.
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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.
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Solar eclipse come in four varieties: ______, annualar, partial, and hybrid.
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Total. In a total eclipse, the sun is completely obscured by the moon. The corona is still visible around the moon.
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An annular eclipse differs from a total eclipse due to the _______ of the moon.
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Apparent size. In this instance, the sun appears as an annualar ring around the silhouette of the moon.
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Hybrid eclipses, intermediary between total and annular eclipses, are _______.
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Rare. At some points on Earth, hybrid eclipses appear total and at others they appear annular.
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A partial eclipse occurs when the moon only _______ obscures the Sun.
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Partially. When only part of the moon enters the umbra, a partial eclipse occurs.
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A _______ eclipse occurs when the Earth moves between the moon and the Sun.
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Lunar. There is always a Full Moon on the evening of a lunar eclipse.
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Earth's shadow can be divided into _____ distinctive parts.
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Two. These are called the umbra and penumbra.
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The darkest part of Earth's shadow is the _______.
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Umbra. There is no direct solar illumination within the umbra.
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The __________ of Earth's shadow is responsible for partial eclipses.
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Penumbra. The penumbra is the part of the shadow surrounding the umbra.
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Observers on Earth ______ see the far side of the moon.
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Cannot. Because the moon's rate of revolution and rotation match ours, we always see the same side of the moon.
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The moon's gravity is ____ ours.
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One-sixth. An object weighing 120 pounds on Earth would measure 20 pounds on the moon.
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The moon's atmosphere is ______.
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Negligble. Because the moon has so little atmosphere, temperatures vary more than 100 degrees between lunar day and night.
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The dark, flat regions of the moon's surface are the ___________.
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Lunar Maria. These low, dry areas were flooded with molten material billions of years ago.
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________ are caused by the impacts of meteoroids.
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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.
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The point of the moon's orbit that brings it closest to Earth is its _____________.
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Perigree. The closest point in an object's orbit of Earth is its perigree.
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The point of the moon's orbit where it is farthest from the Earth is its _____________.
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Apogee. The farthest point in an object's orbit of Earth is its apogee.
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The moon's earthly orbit is _____ days long.
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29.5. Although our year has a solar basis, our months follow the lunar calendar.
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The changes in appearance during the moon's orbit are called its _______.
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Phases. The moon has seven phases: New Moon, First Quarter, Gibbous Moon, Full Moon, Waning Moon, and Third Quarter.
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When the moon appears completely dark from Earth, it is in its _________ phase.
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New. The moon appears dark because it is between the Earth and Sun.
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When the illumination of the moon increases, it is _________.
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Waxing. A Waxing Moon phase is the intemediary phase between New and First Quarter.
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The First Quarter represents the moon phase _____ between New and Full.
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Halfway. The First Quarter moon occurs at the halfway point of the moon's increase in illumination.
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The not-quite-full moon is a ________ moon.
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Gibbous. The Gibbous Moon phase is the period between Quarter and Full as the moon's illumination increases.
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A completely illuminated moon is said to be _____.
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Full. The Full Moon occurs when the side facing the earth is completely illuminated.
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As the moon's illumination begins to decrease, it is said to _____.
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Wane. A Waning Moon describes the period when the visible lighted area of the moon grows smaller.
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The moon phase between Full and New is called the ________.
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Third Quarter.
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The line separating night and day is the ____________.
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Terminator. This line separates the parts of a body experiencing day from the parts experiencing night.
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In July _____, the first humans walked on the moon.
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1969. Neil Armstrong and Buzz Aldrin set foot on the moon on July 20, 1969.
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The rise and fall of an ocean's surface is the ________.
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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.
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The moon's ________ is a major influence on Earth's tides.
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Gravity. The pull of the moon's gravity effectively stretches the earth's oceans into an ellipse with Earth at the center.
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______ Tides are the twice-monthly higher-than-usual high tides.
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Spring. These extra high tides occur when the Sun, Moon, and Earth are in alignment.
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Tides with the greatest difference between high and low tide are called _______ Tides.
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Spring. Low tide generally falls at a relatively constant level, but high tide is variable.
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Tides with the least difference between high and low tide are called _______ Tides.
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Neap. Neap Tides occur twice each month when the Sun and Moon are at Right angles to the earth.
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The two lowest tides in a month are the ______ Tides.
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Neap. Lower-than-usual tides are Neap Tides.
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Most planetary orbits take the form of an __________.
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Ellipse. The planets of our solar system orbit our star in elongated - not perfect - circles.
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_________ is the attractive force between two objects.
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Gravity. The magnitude of this attraction depends on the masses of the involved objects and the distance between them.
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The tendency of an object to stay in motion or remain at rest is called _________.
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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.
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