Astronomy

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How big do the sun and the moon paper from the earth in relation to each other?
The same size
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What is the length of the lunar phase cycle?
29.5 days
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Why is the lunar phase cycle 2.2 days longer than the orbit period of the moon?
This is because as the Moon orbits the Earth the Earth moves relative to the Sun, so an extra couple of days are needed for the Moon to get into the position it was in, relative to the Earth, when the cycle started.
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Why do solar and lunar eclipses occur?
A lunar eclipse occurs when the Earth passes between the Moon and the Sun, and the Earth's shadow obscures the moon or a portion of it. A solar eclipse occurs when the Moon passes between the Earth and the Sun, blocking all or a portion of the Sun.
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What is a solar day?
the time between successive meridian transits of the sun at a particular place.
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What is a sidereal day?
the time between two consecutive transits of the First Point of Aries. It represents the time taken by the earth to rotate on its axis relative to the stars, and is almost four minutes shorter than the solar day because of the earth's orbital motion.
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How can a sundial be used to tell the time?
You can tell the time by looking at the shadow cast by the Sun as it shines on the pointer of a sundial.
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Why is there seasonal variation in the rising and setting of the sun?
The earth's axial tilt
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What does the term apparent sun mean?
The apparent sun is the true sun as seen by an observer on Earth.
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What does the term mean sun mean?
A hypothetical sun defined as moving at a uniform rate along the celestial equator at the mean speed with which the real sun apparently moves along the ecliptic, used in computing the mean solar day.
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What is the equation of time?
Apparent solar time-mean solar time
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What are aurorae and where are they best viewed from?
a natural electrical phenomenon characterized by the appearance of streamers of reddish or greenish light in the sky, especially near the northern or southern magnetic pole.
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How are aurorae caused?
When charged particles from the sun strike atoms in Earth's atmosphere, they cause electrons in the atoms to move to a higher-energy state. When the electrons drop back to a lower energy state, they release a photon: light.
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Other cards in this set

Card 2

Front

What is the length of the lunar phase cycle?

Back

29.5 days

Card 3

Front

Why is the lunar phase cycle 2.2 days longer than the orbit period of the moon?

Back

Preview of the front of card 3

Card 4

Front

Why do solar and lunar eclipses occur?

Back

Preview of the front of card 4

Card 5

Front

What is a solar day?

Back

Preview of the front of card 5
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