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PlanetsMean distance
from sun
in millions
of miles		Semimajor
axis of orbit,
earth's distance
as 1		Eccentricity
of orbit		Inclination of
orbit to elliptic		Light at
perihelion		Light at
apehelion		Heat,
earth as 1
Mercury 36.0 0.387 0.2056 7° 0' 8" 10.58 4.59 6.67
Venus 67.2 0.723 0.0068 3° 23' 35" 1.94 1.91 1.91
The Earth 92.9 1.000 0.068 0° 0' 0" 1.03 0.997 1.00
Mars 141.5 1.524 0.0933 1° 51' 2" 0.52 0.360 1.43
Asteroids 204.4 to 325.2 2.200 to 3.50000.4 to 0.84 5° to 35°
Jupiter 483.3 5.203 0.0483 1° 18' 41" 0.04 0.034 0.037
Saturn 886.0 9.539 0.0561 2° 29' 40" 0.012 0.0099 0.011
Uranus 1781.9 19.183 0.0463 0° 46' 20" 0.0027 0.0025 0.003
Neptune 2791.6 30.055 0.0090 1° 47' 2" 0.0011 0.0011 0.001

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MOVEMENT IN ORBIT.
PlanetsPeriod of
revolution
in years
and days		Orbital
velocity in
miles per
second.		Velocity,
earth's as 1.		Mean diameter
in miles.		Surface
compared
with earth
as 1.		Volume
compared
with earth
as 1.		Mass
compared
with earth
as 1.
Mercury...0.88 23 to 35 1.6 3,000 0.14 0.056 0.13
Venus.....0.224 1/2 21.9 1.17 7,700 0.94 0.92 0.78
The Earth.1.00 18.5 1.0 7,918 1.00 1.00 1.00
Mars......1.88 15.0 0.81 4,230 0.28 0.139 0.124
Asteroids 3.29 to 6.56 From a few
miles to 300
Jupiter.. 11.86 8.1 0.44 86,500 118.3 1309.000316.0
Saturn... 29.46 6.0 0.32 71,000 80.4 760.0 95.0
Uranus.. 84.02 4.2 0.23 31,900 16.3 65.0 14.7
Neptune. 164.78 3.4 0.18 34,800 19.3 90.0 17.1

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DENSITYFORCE OF GRAVITY AT
SURFACE OF PLANET
PlanetsCompared with
earth as 1		Compared with
water as 1		Compared with
earth as 1		Bodies fall
in one second.		Length of
day.		Length of seasonsInclination
of axis.
Mercury. 1.24 7.17 0.85 13.7
Venus... 0.92 5.21 0.83 13.4 hr mn sc
23 21 22 		53+
The Earth.1.00 5.67 1.00 16.09 Spring, 93 days
Summer, 93 days
Autumn, 90 days
Winter, 89 days 		23 1/2
Mars... 0.96 2.54 0.38 6.2 Spring, 191 days
Summer, 181 days
Autumn, 149 days
Winter, 147 days 		27 1/2
Asteroids.
Jupiter. 0.22 1.29 2.55 40.98 9 55 28 1 1/2
Saturn.. 0.13 0.63 1.15 18.53 10 29 17 27
Uranus. 0.18 1.41 0.91 14.6 102(?)
Neptune. 0.20 0.94 0.88 14.2

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"You see," Ayrault explained, "on Jupiter we shall need our apergetic outfits to enable us to make long marches, while on Saturn they will not be necessary, the increase in our weight as a result of that planet's size being considerably less than the usual load carried by the Roman soldier."

"I do not imagine," said Cortlandt, "we should long be troubled by gravitation without our apergetic outfits even on Jupiter, for, though our weight will be more than doubled, we can take off one quarter of the whole by remaining near the equator, their rapid rotation having apparently been given providentially to all the large planets. Nature will adapt herself to this change, as to all others, very readily. Although the reclamation of the vast areas of the North American Arctic Archipelago, Alaska, Siberia, and Antarctic Wilkes Land, from the death-grip of the ice in which they have been held will relieve the pressure of population for another century, at the end of that time it will surely be felt again; it is therefore a consolation to feel that the mighty planets Jupiter and Saturn, which we are coming to look upon as our heritage, will not crush the life out of any human beings by their own weight that may alight upon them."

Before going to bed that evening they decided to be up early the next day, to study Jupiter, which was already a brilliant object.