When the planets appear to slow down or go in reverse, relative to the positions of distant 'fixed' stars.
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From which horizon does the sun rise?
East
3 of 15
Why do stars take slightly less than 24 hours to move across the sky and back to their original position?
The Earth takes just under 24 hours to spin on its axis, which is the same as the length of time it takes for stars to move across the sky.
4 of 15
Why does the moon take slightly more than 24 hours to move across the sky and back to its original position?
Due to the orbit of the Moon around the Earth.
5 of 15
How long is a lunar cycle?
28 days
6 of 15
Describe the position of the Sun, Moon and Earth during a full moon.
The side of the Moon that faces the Earth is fully illuminated by the Sun.
7 of 15
What is a solar eclipse?
When the Moon passes directly between the Sun and the Earth - on the same line - casting a shadow of the Moon on the Erath's surface. (during the new moon phase)
8 of 15
Describe the position of the Sun, Moon and Earth during a lunar eclipse.
The Earth is directly between the Sun and the Moon. (full moon)
9 of 15
Where does an astronomical object appear to be if it has a positive angle of declination?
Above the Northen hemisphere.
10 of 15
When is the vernal equinox?
The day in the springtime when the duration of the day is the same as the duration of the night.
11 of 15
Which direction from the vernal equinox do you measure to find the angle of right ascension?
East
12 of 15
What is a solar day? What is a sidereal day?
A solar day is the time taken for the Sun to move from its highest point in the sky to its highest point in the sky the following day. A sidereal day is the time taken for the Earth to rotate once on its axis.
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What is the difference in time between a sidereal and solar day?
4 minutes. (a solar day is 24 hours, a sidereal day is 23 hours 56 minutes)
14 of 15
Explain the difference between a sidereal and solar day.
A solar day after seeing the Sun straight above at noon, it will be straight above again. A sidereal day later it won't be there - you will need to wait 4 more minutes.
15 of 15
Other cards in this set
Card 2
Front
What is retrograde motion?
Back
When the planets appear to slow down or go in reverse, relative to the positions of distant 'fixed' stars.
Card 3
Front
From which horizon does the sun rise?
Back
Card 4
Front
Why do stars take slightly less than 24 hours to move across the sky and back to their original position?
Back
Card 5
Front
Why does the moon take slightly more than 24 hours to move across the sky and back to its original position?
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