a journey in other worlds-第22章
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〃The temperature and condition of a body；〃 continued Cortlandt；
〃seem to depend entirely on its size。 In the sun we have an
incandescent； gaseous star； though its spots and the colour of
its rays show that it is becoming aged； or； to be more accurate；
advanced in its evolutionary development。 Then comes a great
jump； for Jupiter has but about one fourteen…hundredth of the
mass of the sun； and we expect to find on it a firm crust； and
that the planet itself is at about the fourth or fifth period of
development； described by Moses as days。 Saturn is doubtless
somewhat more advanced。 The earth we know has been habitable
many hundreds of thousands or millions of years； though three
fourths of its surface is still covered by water。 In Mars we see
a further step； three fourths of its surface being land。 In
Mercury； could we study it better； or in the larger satellites of
Jupiter or Saturn； we might find a stepping…stone from Mars to
the moon； perhaps with no water； but still having air； and being
habitable in all other respects。 In our own satellite we see a
world that has died； though its death from an astronomical point
of view is comparatively recent； while this little Pallas has
been dead longer； being probably chilled through and through。
From this I conclude that all bodies in the solar system had one
genesis； and were part of the same nebulous mass。 But this does
not include the other systems and nebulae； for； compared with
them； our sun； as we have seen； is itself advanced and small
beside such stars as Sirius having diameters of twelve million
miles。〃
As they left Pallas between themselves and the sun； it became a
crescent and finally disappeared。
Two days later they sighted another asteroid exactly ahead。 They
examined it closely； and concluded it must be Hilda； put down in
the astronomies as No。 153； and having almost the greatest mean
distance of any of these small bodies from the sun。
When they were so near that the disk was plainly visible to the
unaided eye； Hilda passed between them and Jupiter； eclipsing it。
To their surprise； the light was not instantly shut off； as when
the moon occults a star； but there was evident refraction。
〃By George！〃 said Bearwarden； 〃here is an asteroid that HAS an
atmosphere。〃
There was no mistaking it。 They soon discovered a small ice…cap
at one pole； and then made out oceans and continents； with
mountains； forests； rivers； and green fields。 The sight lasted
but a few moments before they swept by； but they secured several
photographs； and carried a vivid impression in their minds。
Hilda appeared to be about two hundred miles in diameter。
〃How do you account for that living world；〃 Bearwarden asked
Cortlandt； 〃on your theory of size and longevity？〃
〃There are two explanations；〃 replied Cortlandt； 〃if the theory；
as I still believe； is correct。 Hilda has either been brought to
this system from some other less matured； in the train of a
comet； and been captured by the immense power of 〃Jupiter； which
might account for the eccentricity of its orbit； or some accident
has happened to rejuvenate it here。 A collision with another
minor planet moving in an orbit that crossed its own； or with the
head of a large comet； would have reconverted it into a star；
perhaps after it had long been cold。 A comet may first have so
changed the course of one of two small bodies as to make them
collide。 This seems to me the most plausible theory。 Over a
hundred years ago the English astronomer； Chambers； wrote of
having found traces of atmosphere in some of these minor planets；
but it was generally thought he was mistaken。 One reason we know
so little about this great swarm of minor planets is； that till
recently none of them showed a disk to the telescope。 Inasmuch
as only their light was visible； they were indistinguishable from
stars； except by their slow motion。 A hundred years ago only
three hundred and fifty had been discovered； our photographic
star…charts have since then shown the number recorded to exceed
one thousand。〃
CHAPTER IV。
PREPARING TO ALIGHT。
That afternoon Ayrault brought out some statistical tables he had
compiled from a great number of books； and also a diagram of the
comparative sizes of the planets。 〃I have been not a little
puzzled at the discrepancies between even the best authors；〃 he
said； 〃scarcely any two being exactly alike； while every decade
has seen accepted theories radically changed。〃 Saying which； he
spread out the result of his labours （shown on the following
pages）； which the three friends then studied。
…
（1） Mean distance from sun in millions of miles
（2） Semimajor axis of orbit； earth's distance as 1
（3） Eccentricity of orbit
（4） Planets inclination of orbit to elliptic
（5） Light at perihelion
（6） Light at apehelion
（7） Heat； earth as 1
（1） （2） （3） （4） （5） （6） （7）
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 2。200 0。4 to 5@…35@ 325。2 to 3。500 0。34
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
…
（1） MOVEMENT IN ORBIT。 Velocity compared with earth as 1。
（2） MOVEMENT IN ORBIT。 Period of revolution in years and days。
（3） MOVEMENT IN ORBIT。 Orbital velocity in miles per second。
（4） Mean diameter in miles
（5） Surface compared with earth as 1。
（6） Volume compared with earth as 1。
（7） Mass compared with earth as 1。
Planets （1） （2） （3） （4） （5） （6） （7）
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 。。。。 。。。。 From a few to 6。56
miles to 300
Jupiter。。。。。 11。86 8。1 0。44 86；500 118。3 1309。00 316。0
Saturn。。。。。。 29。46 6。0 0。32 1；000 0。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
…
（1） Length of day。 hrs。 min。 sec。
（2） Length of seasons
（3） DENSITY Compared with earth as 1
（4） DENSITY Compared with water as 1
（5） FORCE OF GRAVITY AT SURFACE OF PLANET Compared with earth as
1。
（6） FORCE OF GRAVITY AT SURFACE OF PLANET Bodies fall in one
second。
（7） Inclination of axis。
Planets （1） （2） （3） （4） （5） （6） （7）
Mercury。 。。。。。。。。 。。。。。。。。。 1。24 7。17 0。85 13。7 。。。。。
Venus。。。 23 21 22 。。。。。。。。 0。92 5。21 0。83 13。4 53＋
The Earth。 。。。。。 Spring； 93 1。00 5。67 1。00 16。09 23 1/2
Summer； 93
Terrestrial days Autumn； 90
Winter；89
Mars。。。 24 37 23 Spring； 191 0。96 2。54 0。38 6。2 27 1/2
Summer； 181
Martian days Autumn； 149
Winter； 147
Asteroids。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。
Jupiter。 9 55 28 。。。。。。。。。 0。22 1。29 2。55 40。98 1 1/2
Saturn。。10 29 17 。。。。。。。。。 0。13 0。63 1。15 18。53 27
Uranus。 。。。。。。。 。。。。。。。。。 0。18 1。41 0。91 14。6 102（？）
Neptune。。。。。。。。。 。。。。。。。。。 0。20 0 0。88 14。2 。。。。。
…
〃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 t
