Category: Science - Physics

The Heavens Above: A Popular Handbook of Astronomy

E-text prepared by Colin Bell, Brenda Lewis, David King, and the Online Distributed Proofreading Team (http://www.pgdp.net) from page images generously made available by Internet Archive (https://archive.org)

Chapters

4. Part 4

Here, then, we obtain a first notion of the rotundity of the earth, since a sphere is the only body which is presented always to us under the form of a circle, from whatever poi...

6. Part 6

86. _Cause of Precession._--We have seen that the earth is flattened at the poles: in other words, the earth has the form of a sphere, with a protuberant ring around its equator...

16. Part 16

288. _The Tails of Comets._--The _tails_ of brilliant comets are rapidly formed as the comet approaches the sun, their increase in length often being at the rate of several mill...

15. Part 15

267. _Physical Constitution of Saturn._--The physical constitution of Saturn seems to resemble that of Jupiter; but, being twice as far away, the planet cannot be so well studie...

10. Part 10

The bright-lined spectra of several substances are given in the frontispiece. The number of lines in the spectra of the elements varies greatly. The spectrum of sodium is one of...

2. Part 2

14. _Declination and Right Ascension._--The _declination_ of a heavenly body is its distance north or south of the celestial equator. The _polar distance_ of a heavenly body is...

17. Part 17

307. _Aerolites._--There is no certain evidence that any deposit from ordinary shooting-stars ever reaches the surface of the earth; though a peculiar dust has been found in cer...

13. Part 13

The farther the earth is from the sun, the less rapidly does its shadow taper, and therefore the greater its diameter at the distance of the moon; and, the nearer the moon to th...

1. Part 1

E-text prepared by Colin Bell, Brenda Lewis, David King, and the Online Distributed Proofreading Team (http://www.pgdp.net) from page images generously made available by Interne...

3. Part 3

Since celestial longitude and right ascension are both measured from the first point of Aries, the longitude and right ascension of the stars are slowly changing from year to ye...

14. Part 14

238. _The Volume and Density of Mars._--Among the larger planets Mars is next in size to Mercury. Its real diameter is somewhat more than four thousand miles, and its bulk is ab...

8. Part 8

116. _Lunar Craters._--The smaller saucer-shaped formations on the surface of the moon are called _craters_. They are of all sizes, from a mile to a hundred and fifty miles in d...

7. Part 7

The least retardations for full moon occur when the moon is near the vernal equinox at full: the sun must then be near the autumnal equinox. Hence the least retardations for ful...

11. Part 11

The distortions of the solar lines indicate that the wind at the surface of the sun often blows with a velocity of _from one hundred to three hundred miles a second_. The most v...

20. Part 20

377. _The Great Nebula of Andromeda._--This is one of the few nebulæ that are visible to the naked eye. We see at a glance that it is not a star, but a mass of diffused light. I...

5. Part 5

76. _Diurnal Inequality of Tides._--The height of the tide at a given place is influenced by the declination of the moon. When the moon has no declination, the highest tides sho...

9. Part 9

Although the mass of the sun is over three hundred thousand times that of the earth, the pull of gravity at the surface of the sun is only about twenty-eight times as great as a...

12. Part 12

At times, also, the spectrum of a spot indicates violent motion in the overlying gases by distortion and displacement of the lines. This phenomenon occurs oftener at points near...

19. Part 19

350. _Physically Double and Multiple Stars._--In the majority of cases the components of double and multiple stars are in reality comparatively near together, and are bound toge...

18. Part 18

2-1/2 stars of the 2d magnitude to make one of the 1st. 6 stars of the 3d magnitude to make one of the 1st. 16 stars of the 4th magnitude to make one of the 1st. 40 stars of the...

21. Part 21

Comet, Biela's, 293. and earth, collision of, 316. Coggia's, 297. Donati's, 296. Encke's, 293. Halley's, 291. of 1680, 290. of 1811, 290. of 1843, 295. of 1861, 297. of June, 18...