41. Q. What is the parallax of the moon, and also of the sun, with the semi-equatorial diameter of the earth for a base? A. That of the moon 57 seconds, and that of the nun 8.85 seconds.
42. Q. Taking the diameter of the earth’s orbit, 184 millions of miles, as a base, what can you say of the parallax of the stars? A. They have no apparent parallax on so short a base.
43. Q. What does Prof. Airy say of the orbit of the earth as seen from the nearest star? A. It would be the same as a circle six-tenths of an inch in diameter, seen at the distance of a mile.
44. Q. In what way has the approximate distance of a few of the stars been determined? A. By comparisons of the near and far stars one with another.
45. Q. Which is the nearest star? A. The brightest star in Centaur, never visible in our northern latitudes, which has a parallax of about one second.
46. Q. Which is the next nearest star? A. No. 61 in the Swan, or 61 Cygni, having a parallax of thirty-four one-hundredths of a second.
47. Q. On how many stars have approximate measurements been made? A. About eighteen in all.
48. Q. How long does it take light, traveling at the rate of 185,000 miles a second, to come from the nearest star, Alpha Centauri, to the earth? A. Three and one-fourth years.
49. Q. How long does it take light to come from the Pole Star to the earth? A. Forty-five years.
50. Q. In naming these enormous distances what astronomical unit is used? A. The distance of the earth from the sun, ninety-two and a half millions of miles.
51. Q. In measuring the distance from Alpha Centauri, the nearest star, how many times would this unit be used? A. Two hundred and twenty-six thousand times.
52. Q. What is said of the stars being near or far according to their brightness? A. They are not near or far according to their brightness. 61 Cygni is a telescopic star, while Sirius, the brightest star in the heavens, is twice as far away from us.
53. Q. What is the zodiacal light? A. It is a dim, soft light, somewhat like the milky-way, seen on clear moonless nights in March or April, in the western sky soon after sunset, often reaching, well defined, to the Pleiades.
54. Q. What are the indications as to the cause of this light? A. That it is caused by a ring of small masses of meteoric matter surrounding the sun, revolving with it and reflecting its light, and extending beyond the earth’s orbit.