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Eclipses | |
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Solar
& Lunar Eclipses Intro
to Astronomy Archaeoastronomy |
Can You Answer the Following Questions? GENERAL CONSIDERATIONS
1. The classic configuration (arrangement) of the three bodies which will produce a lunar eclipse is as follows: _______________, _______________, _______________.
2. The alignment which produces a solar eclipse is as follows: _______________, _______________, _______________.
3. Solar eclipses are visible in the DAY/NIGHT (circle one) while lunar eclipse can only be seen AT NIGHT/DURING THE DAY (circle one).
4. A lunar eclipse can only occur when the moon is in the _______________ phase.
5. A solar eclipse can only happen when the moon is in the _______________ phase.
6. The length of time it takes the moon to complete one cycle of phases is equal to _______________ days. This is called the moon's _______________ period.
7. The length of time it takes the moon to make one revolution around the earth is equal to _______________ days. This is called the moon's _______________ period.
8. The difference between these two periods, about 2-1/6 days, is a result of the earth's ___________________________________________________________________ ___________________________________________________________________.
9. Of the two general types of eclipses mentioned in the last several questions, the partial phases of a _______________ eclipse can be very dangerous to view with the unprotected eye.
10. The primary shadow of the moon is termed the _______________, while the secondary shadow of the moon is called the ______________.
11. The primary shadow of the earth is called the _______________, while the secondary shadow of the earth is given the name _______________. Both words are derived from the Latin.
12. During a solar eclipse the color of the moon is _______________, while during a lunar eclipse the moon may appear to be _______________ in color.
13. The atmosphere of the sun, which is visible during a solar eclipse, is called the _______________. Its brightness is equivalent to approximately six full moons. 14. There can be as many as _______________ solar and lunar eclipses occurring during the course of a year.
15. Every year, however, there must be at least _______________ lunar eclipses and a minimum of _______________ solar eclipses.
ECLIPSE TYPES
16. Name the three different types of solar eclipses. _______________, _______________, _______________
17. Name the three different types of lunar eclipses. _______________, _______________, _______________
18. An eclipse in which observers, somewhere on the earth, would experience the umbra of the moon sweep past their position is called a ______________________________.
19. If an observer on the surface of the earth views a ring of sun completely surrounding the moon, the eclipse is said to be ______________________________.
20. If the moon sweeps completely into the shadow of earth, the event can be said to be a ______________________________.
21. The moon enters the secondary shadow of earth, but no part of its surface is occulted by the primary shadow. The eclipse is termed a ______________________________.
22. An eclipse occurs, but no portion of the world has the opportunity of being enveloped by the moon's primary shadow. This type of eclipse is called a ______________________________.
23. If part of the moon sweeps through part of the earth's primary shadow, the eclipse is said to be a _____________________________.
24. Name the two different types of central solar eclipses. _______________, _______________
25. A total lunar eclipse viewed from the earth would appear to an astronaut, standing on the near side of the moon, to be a ______________________________.
PREDICTING ECLIPSES
26. The moon revolves around the earth and the earth orbits the sun in a type of orbital path termed an _______________. 27. The sun and moon appear to change their apparent sizes in the sky because a. ______________________________________________________________________ b. ______________________________________________________________________
28. The average distance of the moon from the earth is ____________________.
29. The average distance of the sun from the earth is ____________________.
30. When the earth is closest to the sun it is at a position called _____________________ (91.5 million miles or 147.5 million km).
31. The moon, on the other hand, recedes to its farthest position from earth at __________________ (253,000 miles or 407,000 km).
32. At its closest location to the earth, the moon is said to be at the position of __________________ (221,000 miles or 356,000 km).
33. When the earth is at its greatest distance from the sun it is said to be at the position of __________________ (94.5 million miles or 152.5 million km).
34. It is the longest line segment of an ellipse, connecting the extremes of distance, the foci, and the center. The line segment is termed the ____________________.
35. Referring to an ellipse, the velocity of a body in orbit is fastest when _______________ to the attracting body and _______________ when farthest from the attracting body.
36. An object in an elliptical orbit lingers for a longer period of time at a distance GREATER/LESSER (circle one) than its average distance.
37. Because the moon is 400 times closer to the earth, but the sun is 400 times larger in diameter, the sun and moon appear to be the _______________ apparent size in the sky. This size is about _______________ degree.
38. If a body is closer, it will appear to be _______________, while if it is farther away, it will appear to be _______________.
39. Since the ovalness (eccentricity) of the lunar orbit is greater than the eccentricity of the earth's orbit, and the moon is closer to the earth than the earth is to the sun, the MOON/SUN (circle one) will vary in size to the greater extent.
40. Since both the moon and the sun are approximately the same apparent size, and it is known that a body in an elliptical orbit will spend more time at a distance farther from its primary than its average distance, the moon normally WILL/WILL NOT (circle one) be large enough to cover the sun's disk completely.
41. Based upon the preceding question, which type of central solar eclipse will be more common: total solar eclipses or annular eclipses? _________________________
42. Which is larger, the earth's diameter or the diameter of the earth's shadow cone at the moon's distance? ____________________
43. Between the two major classifications of central solar eclipses and total lunar eclipses, ____________________ are by far the more common.
44. Why is it that if a poll were taken, more people would say that they had observed a total lunar eclipse than a central solar eclipse? ________________________________________________________________________ ________________________________________________________________________
45. The _______________ is the plane of the earth's orbit projected into space.
46. To create a solar and a lunar eclipse each month, the moon would have to orbit the earth _________________________________________.
47. Since this is not the case, the moon must orbit the earth in a different _________________ than the earth orbits the sun.
48. The moon's orbit intersects the earth's orbit at an angle of approximately ____________________.
49. The intersection positions are called _________________.
50. The position where the moon travels from below the ecliptic to above the ecliptic is referred to as the ____________________. Opposite this location is the position of the ____________________.
51. Most of the time when the moon is new or full it is either above or below the ecliptic and _______________________________________. (Hint: answer this question with respect to eclipses.)
52. An eclipse can occur when two conditions are met. Please note these situations below: a. ___________________________________________________________________ b. ___________________________________________________________________
53. However, things are not all that simple. There is a problem with the nodes. Their location on the ecliptic is continually changing so that in a period of ________________ years they make one revolution around the sky. This is referred to as the _______________ of the moon's nodes.
54. Since the moon's nodes are moving in a _______________ (direction) along the ecliptic, but the moon, due to its orbital motion around the earth, is moving eastward, the moon intersects its nodal point before it has had a chance to complete a full _______________ period.
55. Therefore the nodical period is LONGER/SHORTER (circle one) than the sidereal period.
56. The sidereal period of the moon is approximately _______________ days, while the nodical period (sometimes referred to as the draconic month) is approximately _______________ days.
57. If an eclipse will be occurring today, one can predict the time of the next eclipse by multiplying the nodical and _______________ periods of the moon by integral numbers which will produce products which possess the same number of _______________.
58. If this is done, one will discover that the next eclipse in this cycle will happen 3.8 years into the future. However, it is known that each year there must be at least ________________ solar eclipses and at least _______________ lunar eclipses occurring. The inescapable conclusion is that there must be ______________________________________________ ________________________________________________________________________.
59. There is one other problem we have not considered. We have simply predicted the next eclipse in a series. We don't know if this eclipse will be _________________ to the last eclipse in type.
60. In order to include this parameter, we must now consider the distance of the _________________ from the earth.
61. If the eclipses are to be of the same type, than three considerations must be synchronized. These are as follows: a. _____________________________________________________________________ b. _____________________________________________________________________ c. _____________________________________________________________________
62. If the moon is new, at a node, and at perigee one can definitely say that a ____________________ eclipse will occur.
63. However, in 3.8 years when the moon is new and again at a node, it MAY/MAY NOT (circle one) be at perigee.
64. This is the result of the major axis of the moon's orbit _______________ its orientation in space. The major axis connects the closest distance and farthest distance that a body in an _______________ orbit can be found from its primary. A line drawn through these positions is called the ____________________. 65. The change in the direction of the major axis of the moon's orbit is referred to as the _____________________________________. One complete revolution takes 8.85 years.
66. The period of time it takes the moon to cross its perigee or apogee locations twice is referred to as the _______________ month or period.
67. Since this change is towards the east, in the same direction that the moon revolves, the perigee to perigee time period is LONGER/SHORTER (circle one) than the sidereal period of the moon.
68. The perigee to perigee or apogee to apogee time period for the moon is approximately _____________ days as compared to the sidereal period which is _____________ days.
69. The length of time between similar solar eclipses is the product of the integers of the _______________ month, _______________ month, and the _______________ month which produce a common number of days.
70. The amount of time referred to in the last problem is 18 years, 10 or 11 days and is referred to as the _______________.
71. Therefore, if a total solar eclipse were to occur on the date of March 7, 1970, one could automatically predict that the next similar eclipse would happen on March ,19 or March ,19 .
DURATION OF A SOLAR ECLIPSE
72. The earth rotates from _______________ to _______________, and the moon revolves around the earth towards the direction of _______________. These motions are in DIFFERENT/THE SAME direction (circle one).
73. The velocity of the lunar shadow, due to its orbital motion, is approximately 2000 miles per hour. Since one's ground speed can vary from zero mph at the _______________ to over 1000 mph at the _______________, this can have a drastic effect on the relative velocity of the lunar shadow as it sweeps across the earth's surface.
74. What latitude would offer the possibility of the longest duration in a solar eclipse? _________________
75. The longest duration of totality for a solar eclipse is about 7½ minutes. State three factors which would facilitate such an occurrence, assuming that the observer would be located along the center of the of the lunar umbra. a. ______________________________________________________________________ b. ______________________________________________________________________ c. _______________________________________________________________
76. Because the path of totality of a solar eclipse is so narrow, the most critical factor as to whether one sees totality at all is one's _________________ on the earth's surface.
MISCELLANEOUS INFORMATION
77. In a total solar eclipse, first contact occurs when ________________________________________________________________________.
78. In a total solar eclipse, second contact occurs when ________________________________________________________________________.
79. In a total solar eclipse, third contact occurs when ________________________________________________________________________.
80. In a total solar eclipse, fourth contact occurs when ________________________________________________________________________.
81. In a total solar eclipse, the event is completely safe to view with the naked eye between __________________________________ contacts, but unsafe at any other time.
82. In an eclipse about to become total, the ______________________ occurs just moments before second contact.
83. In a total lunar eclipse, first contact occurs when ________________________________________________________________________.
84. In a total lunar eclipse, second contact occurs when ________________________________________________________________________.
85. In a total lunar eclipse, third contact occurs when ________________________________________________________________________.
86. In a total lunar eclipse, fourth contact occurs when ________________________________________________________________________.
87. It is safe to observe a total lunar eclipse from ________________ contact to ________________ contact.
88. The next total lunar eclipse which will be visible to residents of the Lehigh Valley occurs in (month, year) _____________________.
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