QUESTIONS AND ANSWERS. —— ONE HUNDRED QUESTIONS AND ANSWERS ON “RECREATIONS IN ASTRONOMY,” FROM CHAPTER VIII TO END OF BOOK.

By ALBERT M. MARTIN, General Secretary C. L. S. C.

1. Q. How many primary planets have been discovered between the sun and the earth? A. Six; four planetoids, Mercury and Venus.

2. Q. When and by whom were the four planetoids discovered? A. In 1878, during a total eclipse of the sun, Prof. Watson, of Ann Arbor, Mich., and Lewis Swift, the famous comet-finder, each discovered two small bodies within the orbit of Mercury.

3. Q. What is the distance of these planetoids from the sun? A. About thirteen million miles.

4. Q. What is the time of their orbital revolution? A. About twenty days.

5. Q. What is the mean distance of Mercury from the sun? A. Thirty-five million miles, in round numbers.

6. Q. What is the diameter of Mercury in round numbers? A. Three thousand miles.

7. Q. How does its axial revolution compare with that of the earth? A. It is nearly the same.

8. Q. With what kind of a light does Mercury shine? A. With a white light nearly as bright as Sirius.

9. Q. In what part of the heavens is Mercury to be seen? A. It is always near the horizon.

10. Q. What is the distance of Venus from the sun, in round numbers? A. Sixty-six million miles.

11. Q. How does its diameter compare with that of the earth? A. It is nearly the same.

12. Q. How does its axial revolution compare with that of the earth? A. It is also nearly the same.

13. Q. What is said of the appearance of Venus in the heavens? A. It is the most beautiful object in the heavens, and is often visible in the day time.

14. Q. What is the mean distance of the earth from the sun? A. Ninety-two million five hundred thousand miles.

15. Q. What is the polar and what the equatorial diameter of the earth? A. The polar, 7,899 miles; the equatorial, 7,925-1/2 miles.

16. Q. State three facts in regard to the aurora borealis. A. It prevails mostly near the arctic circle rather than the pole; it is either the cause or the result of electric disturbance; it is often from four to six hundred miles above the earth, while our air can not extend over one hundred miles above the earth.

17. Q. What is the cause of tides? A. The attractive force of the moon and sun.

18. Q. What shores have the greatest tides? A. All eastern shores have far greater tides than western.

19. Q. What is the mean distance of the moon from the earth? A. Two hundred and forty thousand miles.

20. Q. What is the diameter of the moon in round numbers? A. Two thousand miles.

21. Q. What is the time of its revolution about the earth and of its axial revolution? A. Twenty-nine and one-half days.

22. Q. How clearly do the best telescopes we are now enabled to make reveal the moon? A. No more clearly than it would appear to the naked eye if it were 100 or 150 miles away.

23. Q. What is said about the moon presenting the same side to us? A. The moon always presents the same side to the earth.

24. Q. What is the difference of heat on the moon in the full blaze of its noon-day and midnight? A. No less than five hundred degrees.

25. Q. What is said as to the presence of air and water on the moon? A. There are no indications of air or water on the moon.

26. Q. What is said of the maps of the side of the moon toward us? A. They are far more perfect than those of the earth.

27. Q. What planets have been discovered that revolve around the sun outside of the orbit of the earth? A. Mars, asteroids, Jupiter, Saturn, Uranus, and Neptune.

28. Q. What is the mean distance of Mars from the sun? A. One hundred and forty-one million miles.

29. Q. How does the axial revolution of Mars compare with that of Mercury, Venus, and the earth? A. It is nearly the same.

30. Q. What is the diameter of Mars in round numbers? A. Four thousand miles, or one-half that of the earth.

31. Q. What is the appearance of Mars to the naked eye? A. It is the reddest star in the heavens. Sometimes it scintillates, and sometimes it shines with a steady light.

32. Q. How many satellites has Mars? A. Two.

33. Q. When and by whom were they discovered? A. In August, 1877, by Prof. Hall, of Washington, D. C.

34. Q. How many asteroids have been discovered up to the present year? A. Two-hundred and twenty-three.

35. Q. What is the distance of the asteroids from the sun? A. From two hundred million to three hundred and fifteen million miles.

36. Q. What are the diameters of the asteroids? A. From twenty to four hundred miles.

37. Q. How does the mass of all the asteroids compare with that of the earth? A. It is less than one-fourth of the earth.

38. Q. Since what time have all the asteroids known been discovered? A. Since the commencement of the present century.

39. Q. What is the mean distance of Jupiter from the sun? A. 475,692,000 miles.

40. Q. What is the mean diameter of Jupiter? A. Eighty-six thousand miles.

41. Q. What is the volume of Jupiter compared with that of the earth? A. It is thirteen hundred times larger.

42. Q. What is the length of a Jovian day? A. About ten hours.

43. Q. How many satellites has Jupiter. A. Four.

44. Q. What is the mean distance of Saturn from the Sun? A. 881,000,000 miles.

45. Q. What is the mean diameter of Saturn? A. Seventy thousand five hundred miles.

46. Q. How does the time of the axial revolution of Saturn compare with that of Jupiter? A. It is nearly the same.

47. Q. How many moons has Saturn? A. Eight.

48. Q. By what is Saturn surrounded? A. By three rings.

49. Q. What has been proved in reference to the state of Saturn’s rings? A. That they are in a state of fluidity and contraction.

50. Q. What is the mean distance of Uranus from the sun? A. 1,771,000,000 miles.

51. Q. What is the mean diameter of Uranus? A. Thirty-one thousand seven hundred miles.

52. Q. What is the length of the year on Uranus? A. Eighty-four of our years.

53. Q. How many moons has Uranus? A. Four.

54. Q. When and by whom was Uranus discovered? A. By Sir William Herschel in 1781.

55. Q. What is the distance of Neptune from the sun? A. 2,775,000,000 miles.

56. Q. What is the diameter of Neptune? A. Thirty-four thousand five hundred miles.

57. Q. How many moons has Neptune? A. One, and probably two.

58. Q. What is the length of the year on Neptune? A. A little over one hundred and sixty four of our years.

59. Q. When was Neptune discovered? A. In 1846.

60. Q. By what name is the scientific theory known which attempts to state the method by which the solar system came into its present form? A. The nebular hypothesis.

61. Q. How are the stars in a constellation indicated? A. The brightest stars are indicated in order by the letters of the Greek alphabet. After these are exhausted the Roman alphabet is used in the same manner, and then numbers are employed.

62. Q. What have many of the brightest stars also received? A. Proper names by which they are known.

63. Q. Around what star do the stars of the northern circumpolar region appear to revolve? A. Polaris, the North Star.

64. Q. Name five northern circumpolar constellations. A. Ursa Major, or the Great Bear; Ursa Minor; Cepheus; Cassiopeia, or the Lady in the Chair; and Perseus.

65. Q. When are the circumpolar constellations visible in northern latitudes? A. They are always visible.

66. Q. How many stars does the constellation of Ursa Major contain that are visible to the naked eye? A. One hundred and thirty-eight.

67. Q. What does a group of seven stars in this constellation form? A. The Great Dipper.

68. Q. What are the names of the stars in the Dipper? A. The pointers are Dubhe and Merak; the stars forming the handle are Benetnasch, Mizar, and Alioth; the star at the junction of the handle and the bowl is Megrez, and the remaining star at the bottom of the basin is Phad.

69. Q. How many stars does Ursa Minor contain? A. Twenty-four stars, of which only three are of the third, and four of the fourth magnitude.

70. Q. What is a cluster of seven of these stars termed? A. The Little Dipper.

71. Q. What do three stars besides the double pole star form? A. The curved-up handle of the Little Dipper.

72. Q. How many stars visible to the naked eye are contained in the constellation Cepheus? A. Thirty-five.

73. Q. Which is the brightest star of this constellation? A. Alderamin.

74. Q. In what portion of the constellation is Alderamin situated? A. In the right shoulder.

75. Q. What is the position of the head of Cepheus? A. It is in the milky way, and is indicated by a small triangle of three stars.

76. Q. What figure, easily distinguished, do a number of stars in Cassiopeia form? A. An inverted chair.

77. Q. Give the names of two prominent stars in the constellation Perseus. A. Algenib and Algol.

78. Q. Name four of the more brilliant equatorial constellations, only a portion of whose paths is above our horizon. A. Andromeda, Orion, Cygnus, and Canis Major.

79. Q. Give the names applied to some of the groups of stars in the equatorial constellations. A. The Pleiades, the Great Square of Pegasus, the Belt of Orion, and the Milk Dipper.

80. Q. Name eight stars of the first magnitude in the equatorial constellations. A. Aldebaran, in Taurus; Capella, the Goat Star, in Auriga; Castor, in Gemini; Betelgeuse, in Orion; Sirius, the Dog Star, in Canis Major; Procyon, in Canis Minor; Spica, in Virgo; and Arcturus, in Boötes.

81. Q. What are some of the more remarkable sights in the southern circumpolar region of the sky? A. The constellations of the ship Argo and the Southern Cross, the Dark Hole, and the two Magellanic Clouds.

82. Q. How many stars are visible in the whole heavens to the naked eye? A. About five thousand.

83. Q. How many are there of each magnitude to the sixth? A. Twenty of the first, sixty-five of the second, two hundred of the third, four hundred of the fourth, eleven hundred of the fifth, and thirty-two hundred of the sixth.

84. Q. How many stars are there in the zone called the Milky Way? A. Eighty millions.

85. Q. How much of the light on a fine starlight night comes from stars that cannot be discerned by the naked eye? A. Three-fourths.

86. Q. How does the whole amount of starlight compare with that of the moon? A. It is about one-eightieth that of the moon.

87. Q. Give the names of five double or multiple stars. A. Polaris, Sirius, Procyon, Castor, and sixty-one Cygni.

88. Q. What is said of the color of stars? A. They are of various colors.

89. Q. Name five stars each having a different color. A. Sirius, white; Capella, yellow; Castor, green; Aldebaran, red; and Lyra, blue.

90. Q. What are clusters of stars? A. In various parts of the heavens there are small globular well-defined clusters, and clusters very irregular in form marked with sprays of stars.

91. Q. How do these clusters appear to the eye, or through a small telescope? A. As little cloudlets of hazy light.

92. Q. What is the new and better substantiated possibility of thought concerning these clusters? A. That they belong to our system, and hence that the stars must be small and young.

93. Q. What does the spectroscope show that some of these little cloudlets of hazy light called nebulæ are? A. That they are not stars in any sense, but masses of glowing gas.

94. Q. What are some of the shapes of nebulæ? A. Nebulæ are of all conceivable shapes—circular, annular, oval, lenticular, conical, spiral, snake-like, looped, and nameless.

95. Q. Of how many stars has a variation in magnitude been well ascertained? A. One hundred and forty-three.

96. Q. What are temporary stars? A. Those that shine awhile and then disappear.

97. Q. What are new stars? A. Stars that come to a definite brightness and so remain.

98. Q. What are lost stars? A. Those whose first appearance was not observed, but which have utterly disappeared.

99. Q. What movements have these stars? A. There is motion of the stars in every conceivable direction.

100. Q. What is said of the appearance of the Great Dipper in thirty-six thousand years? A. The end of the dipper will have fallen out so that it will hold no water, and the handle will be broken square off at Mizar.