), familiar as the conspicuous
red star in the right shoulder of Orion (Hubble)
26. Arcturus (within the white circle), known to the Arabs as the "Lance
Bearer," and to the Chinese as the "Great Horn" or the "Palace of the
Emperors" (Hubble)
27. The giant star Antares (within the white circle), notable for its red
color in the constellation Scorpio, and named by the Greeks "A Rival
of Mars" (Hubble)
28. Diameters of the Sun, Arcturus, Betelgeuse, and Antares compared with
the orbit of Mars
29. Aldebaran, the "leader" (of the Pleiades), was also known to the Arabs
as "The Eye of the Bull," "The Heart of the Bull," and "The Great
Camel" (Hubble)
30. Solar prominences, photographed with the spectroheliograph without an
eclipse (Ellerman)
31. The 150-foot tower telescope of the Mount Wilson Observatory
32. Pasadena Laboratory of the Mount Wilson Observatory
33. Sun-spot vortex in the upper hydrogen atmosphere (Benioff)
34. Splitting of spectrum lines by a magnetic field (Bacock)
35. Electric furnace in the Pasadena Laboratory of the Mount Wilson
Observatory
36. Titanium oxide in red stars
37. Titanium oxide in sun-spots
38. The Cavendish experiment
39. The Trifid Nebula in Sagittarius (Ritchey)
40. Spiral nebula in Ursa Major (Ritchey)
41. Mount San Antonio as seen from Mount Wilson

CHAPTER I

THE NEW HEAVENS

Go out under the open sky, on a clear and moon-less night, and try
to count the stars. If your station lies well beyond the glare of
cities, which is often strong enough to conceal all but the brighter
objects, you will find the task a difficult one. Ranging through
the six magnitudes of the Greek astronomers, from the brilliant
Sirius to the faintest perceptible points of light, the stars are
scattered in great profusion over the celestial vault. Their number
seems limitless, yet actual count will show that the eye has been
deceived. In a survey of the entire heavens, from pole to pole,
it would not be possible to detect more than from six to seven
thousand stars with the naked eye. From a single viewpoint, even
with the keenest vision, only two or three thousand can be seen.
So many of these are at the limit of visibility that Ptolemy's
"Almagest," a catalogue of all the stars whose places were measured
with the simple instruments of the Greek astronomers, contains
only 1,022 stars.

Back of Ptolemy, through the speculations of the