Name.

Mean

Distance

From Earth in Millions of Miles.

Mean

Distance

From Sun,

Millions of

Miles.

Sidereal

Period,

Days.

Orbit

Velocity,

Miles per

Second.

Mean

Diameter,

Miles.

Sun

92.9

866,400

Mercury

56.9

36.0

87.969

23 to 35

3,030

Venus

25.7

67.2

224.701

21.9

7,700

Earth............

92.9

365.256

18.5

7,918

Mars

48.6

141.5

686.950

15.0

4,230

Jupiter

390.4

483.3

4,332.58

8.1

86,500

Saturn

793.2

886.0

10,759.22

6.0

71,000

Uranus

1,689.0

1,781.9

30,686.82

4.2

31,900

Neptune

2,698.8

2,791.6

60,181.11

3.4

31,800

The number of asteroids discovered up to present date is 330. A number of these small planets have not been observed since their discovery, and are practically lost. Consequently it is now sometimes a matter of doubt, until the elements have been computed, if the supposed new planet is really new, or only an old one rediscovered.

It is supposed that a Centuri, one of the brightest stars of the Southern Hemisphere, is the nearest of the fixed stars to the earth. The researches on its parallax by Henderson and Maclear gave it for its distance from the earth, in round numbers, 20,000.000,000,000 of miles. At the inconceivably rapid rate at which light is propagated through space, it would require three years and three months to reach the earth from this star.