WHEN we raise our eyes to the heavens on a clear night, thousands of bright objects claim our attention. We observe that all these objects move as if they were fastened to the inside of an invisible sphere. They are seen gradually ascending3 from the east, passing across the south, and in due course sinking towards the west. The sun and the moon, as well as all the other bodies, alike participate in this great diurnal movement. The whole scheme of celestial objects seems to turn around the two points in the heavens that we call the Poles, and so far as the pole in the northern hemisphere is concerned, its position is most conveniently indicated by the proximity4 of the well-known Pole Star.
Except this great diurnal motion, the vast majority 22of the bodies on the celestial sphere have no other movement easily recognisable, and certainly none which it is necessary for us to consider at present. The groups in which the stars have been arranged by the poetical5 imagination of the ancients exist to-day, as they have existed during all the ages since they were first recognised, without any noticeable alteration6 in their lineaments. The stately belt of Orion is seen to-night as Job beheld7 it thousands of years ago; the stars in the Pleiades have not altered their positions, relatively8 to the adjacent stars nor their arrangement among themselves, since the time when astronomers10 in early Greece observed them. All the bodies which form these groups are therefore known as fixed11 stars.
But besides the fixed stars, which exist in many thousands, and, of course, the sun and the moon, there are other celestial objects, so few in number as to be counted on the fingers of one hand, which are in no sense fixed stars. It is quite true that these wandering bodies, or planets, as they are generally designated, bear a certain resemblance to the fixed stars. In each case the star or the planet appears as a bright point, like many other bright points in the heavens, and star and planet both participate in the general diurnal motion. But a little attention will show that while the stars, properly so called, retain their relative places for months and years and centuries, the planets change their places so rapidly that in the course of a few nights it is quite easy to see, even without the aid of any instrument, that they have independent motion.
We may compare the movements of these bodies to the movement of the moon, which nightly shifts her place over a long track in the sky; and although we 23are not able to see the stars in the vicinity of the sun, inasmuch as the brilliant light of the orb12 quenches13 the feeble radiance from such stars, there is no doubt that, did we see them, the sun itself would seem to move relatively to the stars, just as does the moon and just as do the planets.
The fundamental distinction between stars and planets was noticed by acute observers of Nature in the very earliest times. The names of the planets come to us as survivals from the time when the sun, the moon, and the stars were objects of worship, and they come to us bearing the names of the deities14 of which these moving globes were regarded as the symbols. But it was not the movements of the planets alone which called for the notice of the early observers of the skies. The brightness and certain other features peculiar15 to them also attracted the attention of the primitive16 astronomers. They could not fail to observe that when the beautiful planet Venus was placed so as to be seen to the greatest advantage, her orb was far brighter than any other object in the host of heaven, the sun and the moon both of course excepted. It was also obvious that Jupiter at its best exceeded the stars in lustre17, and sometimes approached even to that of Venus itself. Though Mercury was generally so close to the sun as to be invisible among its beams, yet on the rare occasions when that planet was seen, just after sunset or just before sunrise, its lustre was such as to mark it out as one of the remarkable18 bodies in the heavens.
Thus the astronomers of the earliest ages pointed19 to the five planets and the sun and the moon as the 24seven wandering stars. The diligent20 attention of the learned of every subsequent period was given to the discovery of the character of their movements. The problems that these motions presented were, however, so difficult that not until after the lapse21 of thousands of years did their nature become understood. The supreme22 importance of the earth appeared so obvious to the early astronomers that it did not at first occur to them to assign to our earth a position which would reduce it to the same class as any of the celestial bodies. The obviously great size of our globe, the fact that to the uninstructed senses the earth seemed to be at rest, while the other bodies seemed to be in motion, and many other analogous23 circumstances, appeared to show that the earth must be a body totally different from the other objects distributed around us in space. It was only by slow degrees, and after much observation and reflection, and not a little controversy24, that at last the true nature of our system was detected. Those who have been brought up from childhood in full knowledge of the rotation25 of the earth and of the other fundamental facts relating to the celestial sphere, will often find it difficult to realise the way such problems must have presented themselves to the observers of old, who believed, as for centuries men did believe, that the earth was a plane of indefinite extent fixed in space, and that the sun and the planets, the moon and the stars, were relatively small bodies whose movements must be accounted for as best they could be, consistently with the fixity and flatness of the earth.
25
(E. M. Antoniadi.)
But at last it began to be seen that the earth must be relegated27 to a position infinitely28 less important than that which the untutored imagination assigned to it. It was found that the earth was not an indefinite plane; it was rather a globe poised29 in space, without direct material support from any other body. It was found that the earth was turning round on its axis30: while instead of the sun revolving31 around the earth, it was much more correct to say that the earth revolved32 around the sun. The astonishing truth was then disclosed that the five planets, Jupiter and Saturn34, Mercury, Venus and Mars, stood in a remarkable relation to the earth. For as each of these planets was found to revolve33 round the 26sun, and as the earth also revolved round the sun, the assumed difference in character between the earth and the planets tended to vanish altogether. There was in fact no essential difference. If indeed the earth was smaller than Jupiter and Saturn, yet it was considerably35 greater and heavier than Mars or Mercury, and it was almost exactly the same size and weight as Venus. There was clearly nothing in the question of bulk to indicate any marked difference between our earth and the planets. It was also observed that there was no distinction to be drawn36 between the way in which the earth revolved round the sun and the movements of the planets. No doubt the earth is not so near the sun as Mercury; it is not so near the sun as even Venus; on the other hand the sun is nearer the earth than Mars, while Jupiter is a long way further off than Mars, and Saturn is even beyond Jupiter again. It is these considerations which justify37 us in regarding our earth as one of the planets. We have also to note the overwhelming magnitude of the sun in comparison with any one of the planets. It will suffice to give a single illustration. The sun is more than a thousand times as massive as Jupiter, and Jupiter is the greatest of the planets. This latter noble globe is in fact greater than all the rest of the planets put together.
But before we can fully38 realise the circumstances of the solar system, it will be necessary to see how the stars, properly so called, enter into the scheme of things celestial. The stars look so like the planets that it has not infrequently happened that even an experienced astronomer9 has mistaken one for the 27other. The planet Mars is often very like the star Aldebaran, and there are not a few first-magnitude stars which on a superficial view closely resemble Saturn. But how great is the intrinsic difference between a star and a planet! In the first place we have to note that every planet is a dark object like this earth of ours, possessing no light of its own, and dependent entirely39 on the sun for the supply of light by which it is illumined. But a star is totally different. The star is not a dark object, but is really an object which is in itself intensely luminous40 and brilliant; the star is in fact a sun-like body. How then, it may well be asked, does a star like Aldebaran, which is indeed a sun-like body, and in all probability is quite as large and quite as brilliant as the sun itself, bear even a superficial resemblance to an object like Mars, which would not be visible at all were it not for the illumination with which the beams from the sun endow it?
The explanation of this striking resemblance is to be sought in the relative distances of the two objects. A light which is near to the eye may produce an effect quite as great as a very much stronger light which is further away. The intensity41 of a light varies inversely42 as the square of the distance. If the distance of a light from the eye be doubled, then the intensity of that light is reduced to one-fourth. Now Aldebaran as a sun-like body emits light which is literally43 millions of times as great as the gleam of sunshine which starts back to us after reflection from Mars; but Aldebaran is, let us say, a million times as far away from us as Mars, and this being so, the light from Aldebaran would come to us with only a million-millionth 28part of the intensity that it would have if the star were at the same distance as the planet. There can be no doubt that if Aldebaran were merely at the same distance from the earth as Mars, then Aldebaran would dispense45 lustre like a splendid sun. By moving Aldebaran further off its light, or rather the light that arrives at the earth, will gradually decrease until by the time that the star is a million times as far as Mars, the light that it sends us is about equal to that of Mars. If it were removed further still, the light that it would send us would become less than that which we receive from Mars, and if still more remote, Aldebaran might cease to be visible altogether.
This illustration will suffice to explain the fundamental difference between planets and stars, notwithstanding the fact that the two classes of bodies bear to each other a resemblance which is extremely remarkable, even if it must be described as being in a sense accidental. But we now know that all of the thousands of stars are to be regarded as brilliant suns, some of which may not be so far off as Aldebaran, though doubtless some are very much further. The actual distances are immaterial, for the essential point to notice is that the five planets are distinguished46 from the stars, not merely by the fact that they are moving, while the stars are at rest, but by the circumstance that the planets are comparatively close to each other and close to the sun, while the stars are at distances millions of times as great as the distances which the planets are from each other and from the sun.
We are now enabled to place the scheme of things 29celestial in its proper perspective. I shall suppose that at a point in a field in the centre of England, somewhere near Leamington, let us say, we drive in a peg47 to represent the sun. Let us draw a circle with that peg as centre, a yard being the radius48, and let that circle represent the track in which the earth goes round the sun. I do not indeed say that the orbit of the earth is exactly a circle, and the actual shape of that orbit we may have to refer to later. As, however, the apparent size of the sun does not greatly alter with the seasons, it is evident that the track which our earth pursues cannot be very different from a circular path. Inside this circle which we have drawn with a yard radius, we shall put two smaller circles which are to represent the path in which Venus moves, and the path in which Mercury moves. Outside the path of the earth we shall draw another circle with a radius of five yards; this will be the highway along which the majestic49 Jupiter wends his way. Inside the path of Jupiter we shall put a circle which will represent the track of Mars, and outside the path of Jupiter a circle with ten yards as radius will represent the track of Saturn. In each of these circles we shall suppose the corresponding planet to revolve, and the time of revolution will of course be greater the further the planet is from the sun. To complete one of its circuits the earth will require a year, Jupiter twelve years, while Saturn, which in the ancient astronomy moved on the frontier of the solar system, will need thirty years to accomplish its mighty50 journey.
We have thus obtained a plan of the solar system; but now we should like to indicate the 30positions which some of the stars are to occupy on the same scale. Let us, to begin with, see where the very nearest fixed star is to be placed. We may suppose that the field at the centre of England, in which our little diagram has been constructed, is a large one, so that we can represent the places of objects which are ten or twenty times as far from the sun as Saturn. It is, however, certain that no actual field would be large enough to contain within its bounds the points which would faithfully represent the positions of even the nearest fixed stars. The whole county of Warwick would not be nearly big enough for this purpose; indeed we may say that the whole of England, or indeed of the United Kingdom, would not be sufficiently51 extensive. If we represented the star at its true relative distance, it could not be put down anywhere within the bounds of the United Kingdom; the nearest object of this kind would have to be far away out on the continent of Europe, or far away out on the Atlantic Ocean, far away down near the equator, or far away up near the pole. This illustration will at all events give some notion of the isolated52 position of the sun, with the planets revolving around it, in relation to the rest of the host of heaven.
We thus learn that the real scheme of the universe is widely different from that which a superficial glance at the heavens would lead us to expect. We are now able to put our system into its proper perspective. We are to think of the universe as consisting of a myriad53 suns, each sun, however, being so far from the other suns that viewed from any one of its neighbours it appears only of star-like insignificance54. 31Let us fix our attention on one of these suns in space, and imagine that around it, and comparatively close to it, there are a number of small particles in revolution, the particles being illumined by the light and warmed by the heat of the central body to which they are attached. Viewed from one of those particles, the sun to which they belong would doubtless appear as a great and glorious orb, while a glance from one of these particles to any of the other myriad suns in space will show these orbs55 reduced to mere44 points of stellar light by reason of their enormous distance. This sun and the particles around it, by which of course we shall understand the planets, constitute what we know as the solar system. This illustration may suffice to show the isolation56 of our system in space, and that isolation is due to the vast distances by which the sun and its attendant worlds are separated from the myriads57 of other bodies which form the sidereal58 heavens. We must next, so far as our present subject requires it, consider the laws according to which the planets belonging to that system revolve around the sun.
Let us think first of a single one of these bodies which, as is most natural, we shall take to be the earth itself, and now let us consider by what agency the movement of the earth around the sun is guided along the path which so closely resembles a circle. It must, of course, be borne in mind that there can be no direct material connection between the two bodies; there is no physical bond uniting the earth to the sun. It is, however, certain that some influence proceeding59 from the sun does really control the motion. We may perhaps illustrate60 what takes place 32in the following manner. Here is a globe, and here in my hand I hold a tennis ball, which is attached to a silken thread, the other end of the thread being attached to the ceiling. The tennis ball is to hang so that both globe and ball are about the same height from the floor. We put the globe directly underneath61 the point on the ceiling from which the silken thread hangs. If I draw the tennis ball aside and simply release it, then of course everybody knows what happens—it is hardly necessary to try the experiment—the tennis ball falls at once towards the globe and strikes it. We may, if we please, regard that tendency of the tennis ball towards the globe as a sort of attraction which the globe exercises upon the ball. I must, however, say that this is not a strictly62 accurate version of what actually takes place. The attraction of the earth for the tennis ball is of course largely neutralised by the support given by the silk thread. There is thus only a slight outstanding component63 of gravitation acting64 on the ball, and this component, which is virtually the effective force on the ball, tends to draw the ball directly towards the globe. For the purpose of our illustration we may neglect the direct attraction of the earth altogether; we may omit all thought of the tension of the silken thread. If there were indeed no attraction from the earth, the tennis ball might remain poised in space without falling; and if it were then attracted by the globe it would fly towards the globe just as we actually see it do. We are therefore justified65 in regarding the movement of the tennis ball as equivalent to that which would be produced if an attractive virtue66 resided in the globe by which 34it pulled the tennis ball. We may also imagine that the globe attracts the tennis ball in all its positions; for whatever be the point at which the ball is released it starts off straight towards the globe. This is our first experiment in which, having withdrawn67 the ball, it is merely released without receiving an initial impulse to one side.
Fig. 5.—Nebulous Region and Star-Cluster
(n.g.c. 2237-9 in Monoceros).
(Photographed by Dr. Isaac Roberts, F.R.S.)
Let us now try a different experiment. We withdraw the ball, and, instead of merely releasing it quietly and allowing it to drop directly to the globe, we give it a little throw sideways, perpendicular68 to the line joining it to the centre of the globe. If we start it with the proper speed, which a few trials will indicate, the ball can be made actually to move in a circle round the globe. If the initial speed be somewhat different, the path in which the tennis ball moves will not be a circle; it will rather be an ellipse of some form. Even if the speed be correct the orbit will always be an ellipse if the direction of the initial throw be not perpendicular to the line joining the ball to the centre of the globe. We can make the ball describe a very long ellipse or an ellipse which differs but little from a circle. But I would ask you to note particularly that, no matter how we may start the tennis ball into motion, it will, so long as it passes clear of the globe, move in an ellipse of some kind; but in making this statement we assume that a circle is a particular form of the ellipse.
And now for the lesson which we are to learn from this experiment, which, as it is so easily performed, I would wish everyone to try for himself. We have in this simple device an illustration of the movement of a planet around the sun. We see that 35this tennis ball can be made to move in a circle round the globe, and that as it performs this circular movement the globe is all the time attracting the ball towards it. Thus we illustrate the important law that when one body moves round another in a circular path this movement takes place in consequence of a force of attraction constantly exerted between the large body in the centre and the body revolving round it.
The principle here involved will provide the explanation of the movements of the planets round the sun. Each of the planets revolves69 round the sun in an orbit which is approximately circular, and each of the planets performs that movement because it is continually attracted by the sun. It is, however, necessary to add that there is a fundamental difference between the attraction of the sun for the planets and the attraction which the globe appeared to exert on the tennis ball in our experiment. The difference relates to the character of the forces in the two cases. If the tennis ball be drawn but a very small distance from the globe, the attraction between the two bodies is very slight. If the tennis ball be drawn to a greater distance from the globe, the attraction is increased correspondingly; and, indeed, in this experiment the attraction between the two bodies increases with the distance, and is said to be proportional to the distance.
But the case is very different in that particular kind of attraction by which the sun controls the movements of the planets. This attraction of gravitation, as it is called, also depends on the distance between the two bodies. But the attraction does not increase when the 36distance of the two bodies increases, for the change lies the other way. The attraction, in fact, diminishes more rapidly than the distance increases. If the distance between the sun and a planet be doubled, then the attraction between the two bodies is only a fourth of what the attraction was between the two bodies in the former case. This difference between the law of attraction as it exists in the solar system and the law of attraction which is exemplified in our little experiment produces a remarkable contrast in the resulting movements. The orbit in each case is, no doubt, an ellipse, but in the case of the tennis ball revolving round the globe the ellipse is so circumstanced that the fixed attracting body stood at its centre, while in the case of a planet revolving round the sun the conditions are not so simple. The sun does not stand in the centre of the ellipse. The sun is placed at that remarkable point of the ellipse so dear to the heart of the geometer, which he calls the focus.
The solar system consists, first, of the great regulating orb, the sun; then of the planets, each of which revolves in its own track round the sun; each of these tracks is an ellipse, and all these ellipses70 have this in common, that a focus in each is identical with the centre of the sun. In other respects the ellipses may be quite different. To begin with, they are not in the same plane, though it is most important to notice, as we shall have to discuss more fully hereafter, that these planes are not very much separated. The dimensions of the ellipses vary, of course, for the different planets, and the periods that the planets require for their several revolutions are also widely different in the cases of the different bodies; for the greater the diameter of 37a planet’s orbit, the longer is the time required for that planet to complete a single journey round the sun. The sun presiding at the common focus of the orbits while governing the planets by its attraction, at the same time that it illumines them with its light and warms them by its rays, gives the conception of the solar system.
But the planetary system I have here indicated is merely that system as known to the ancients. It is very imperfect from the standpoint of our present knowledge. The solar system as we now know it, when telescopes have been applied71 with such marvellous diligence and success to the discovery of new bodies, is a system of much greater complexity72. To the five old planets have been added two new and majestic planets—Uranus73 and Neptune74—which revolve outside the track of Saturn. Hundreds of smaller planets, invisible to the unaided eye, the asteroids75 as they are called, also describe their ellipses round the presiding luminary76. And then just as the sun controls the planets revolving round it, so do many of the planets themselves preside over subordinate systems of revolving globes. Our earth has a single attendant, the moon, which, under the guidance of the earth’s attraction, performs its monthly journey; Jupiter has its five moons, while Mars has two, and Saturn eight or nine, besides his incomparable system of rings, and we must also add that Uranus has four satellites and Neptune one. To complete the tale of bodies in the solar system, we should add many thousands of comets, not to mention their more humble77 associates the meteors, which swarm78 in countless79 myriads. Finally, we are to remember that this elaborate system associated with 38the sun is an isolated object in the universe; it is but as a grain of sand in the extent of infinite space.
As we contemplate80 a system so wonderful, the question naturally arises, How came that system into being? We have to consider whether the laws of nature as we know them afford any rational explanation of the manner in which this system came into existence, any rational explanation of how the sun came to shine, how the earth had its beginning, how the planets came to revolve round the sun, and to rotate on their own axes. We have to seek for a rational explanation of the rings of Saturn, and of the satellites by which so many planets are attended. We have to show that a satisfactory explanation of these remarkable phenomena81 is forthcoming, and that it is provided by the famous doctrine82 of evolution, which it is the object of these lectures to discuss.
点击收听单词发音
1 diurnal | |
adj.白天的,每日的 | |
参考例句: |
|
|
2 celestial | |
adj.天体的;天上的 | |
参考例句: |
|
|
3 ascending | |
adj.上升的,向上的 | |
参考例句: |
|
|
4 proximity | |
n.接近,邻近 | |
参考例句: |
|
|
5 poetical | |
adj.似诗人的;诗一般的;韵文的;富有诗意的 | |
参考例句: |
|
|
6 alteration | |
n.变更,改变;蚀变 | |
参考例句: |
|
|
7 beheld | |
v.看,注视( behold的过去式和过去分词 );瞧;看呀;(叙述中用于引出某人意外的出现)哎哟 | |
参考例句: |
|
|
8 relatively | |
adv.比较...地,相对地 | |
参考例句: |
|
|
9 astronomer | |
n.天文学家 | |
参考例句: |
|
|
10 astronomers | |
n.天文学者,天文学家( astronomer的名词复数 ) | |
参考例句: |
|
|
11 fixed | |
adj.固定的,不变的,准备好的;(计算机)固定的 | |
参考例句: |
|
|
12 orb | |
n.太阳;星球;v.弄圆;成球形 | |
参考例句: |
|
|
13 quenches | |
解(渴)( quench的第三人称单数 ); 终止(某事物); (用水)扑灭(火焰等); 将(热物体)放入水中急速冷却 | |
参考例句: |
|
|
14 deities | |
n.神,女神( deity的名词复数 );神祗;神灵;神明 | |
参考例句: |
|
|
15 peculiar | |
adj.古怪的,异常的;特殊的,特有的 | |
参考例句: |
|
|
16 primitive | |
adj.原始的;简单的;n.原(始)人,原始事物 | |
参考例句: |
|
|
17 lustre | |
n.光亮,光泽;荣誉 | |
参考例句: |
|
|
18 remarkable | |
adj.显著的,异常的,非凡的,值得注意的 | |
参考例句: |
|
|
19 pointed | |
adj.尖的,直截了当的 | |
参考例句: |
|
|
20 diligent | |
adj.勤勉的,勤奋的 | |
参考例句: |
|
|
21 lapse | |
n.过失,流逝,失效,抛弃信仰,间隔;vi.堕落,停止,失效,流逝;vt.使失效 | |
参考例句: |
|
|
22 supreme | |
adj.极度的,最重要的;至高的,最高的 | |
参考例句: |
|
|
23 analogous | |
adj.相似的;类似的 | |
参考例句: |
|
|
24 controversy | |
n.争论,辩论,争吵 | |
参考例句: |
|
|
25 rotation | |
n.旋转;循环,轮流 | |
参考例句: |
|
|
26 fig | |
n.无花果(树) | |
参考例句: |
|
|
27 relegated | |
v.使降级( relegate的过去式和过去分词 );使降职;转移;把…归类 | |
参考例句: |
|
|
28 infinitely | |
adv.无限地,无穷地 | |
参考例句: |
|
|
29 poised | |
a.摆好姿势不动的 | |
参考例句: |
|
|
30 axis | |
n.轴,轴线,中心线;坐标轴,基准线 | |
参考例句: |
|
|
31 revolving | |
adj.旋转的,轮转式的;循环的v.(使)旋转( revolve的现在分词 );细想 | |
参考例句: |
|
|
32 revolved | |
v.(使)旋转( revolve的过去式和过去分词 );细想 | |
参考例句: |
|
|
33 revolve | |
vi.(使)旋转;循环出现 | |
参考例句: |
|
|
34 Saturn | |
n.农神,土星 | |
参考例句: |
|
|
35 considerably | |
adv.极大地;相当大地;在很大程度上 | |
参考例句: |
|
|
36 drawn | |
v.拖,拉,拔出;adj.憔悴的,紧张的 | |
参考例句: |
|
|
37 justify | |
vt.证明…正当(或有理),为…辩护 | |
参考例句: |
|
|
38 fully | |
adv.完全地,全部地,彻底地;充分地 | |
参考例句: |
|
|
39 entirely | |
ad.全部地,完整地;完全地,彻底地 | |
参考例句: |
|
|
40 luminous | |
adj.发光的,发亮的;光明的;明白易懂的;有启发的 | |
参考例句: |
|
|
41 intensity | |
n.强烈,剧烈;强度;烈度 | |
参考例句: |
|
|
42 inversely | |
adj.相反的 | |
参考例句: |
|
|
43 literally | |
adv.照字面意义,逐字地;确实 | |
参考例句: |
|
|
44 mere | |
adj.纯粹的;仅仅,只不过 | |
参考例句: |
|
|
45 dispense | |
vt.分配,分发;配(药),发(药);实施 | |
参考例句: |
|
|
46 distinguished | |
adj.卓越的,杰出的,著名的 | |
参考例句: |
|
|
47 peg | |
n.木栓,木钉;vt.用木钉钉,用短桩固定 | |
参考例句: |
|
|
48 radius | |
n.半径,半径范围;有效航程,范围,界限 | |
参考例句: |
|
|
49 majestic | |
adj.雄伟的,壮丽的,庄严的,威严的,崇高的 | |
参考例句: |
|
|
50 mighty | |
adj.强有力的;巨大的 | |
参考例句: |
|
|
51 sufficiently | |
adv.足够地,充分地 | |
参考例句: |
|
|
52 isolated | |
adj.与世隔绝的 | |
参考例句: |
|
|
53 myriad | |
adj.无数的;n.无数,极大数量 | |
参考例句: |
|
|
54 insignificance | |
n.不重要;无价值;无意义 | |
参考例句: |
|
|
55 orbs | |
abbr.off-reservation boarding school 在校寄宿学校n.球,天体,圆形物( orb的名词复数 ) | |
参考例句: |
|
|
56 isolation | |
n.隔离,孤立,分解,分离 | |
参考例句: |
|
|
57 myriads | |
n.无数,极大数量( myriad的名词复数 ) | |
参考例句: |
|
|
58 sidereal | |
adj.恒星的 | |
参考例句: |
|
|
59 proceeding | |
n.行动,进行,(pl.)会议录,学报 | |
参考例句: |
|
|
60 illustrate | |
v.举例说明,阐明;图解,加插图 | |
参考例句: |
|
|
61 underneath | |
adj.在...下面,在...底下;adv.在下面 | |
参考例句: |
|
|
62 strictly | |
adv.严厉地,严格地;严密地 | |
参考例句: |
|
|
63 component | |
n.组成部分,成分,元件;adj.组成的,合成的 | |
参考例句: |
|
|
64 acting | |
n.演戏,行为,假装;adj.代理的,临时的,演出用的 | |
参考例句: |
|
|
65 justified | |
a.正当的,有理的 | |
参考例句: |
|
|
66 virtue | |
n.德行,美德;贞操;优点;功效,效力 | |
参考例句: |
|
|
67 withdrawn | |
vt.收回;使退出;vi.撤退,退出 | |
参考例句: |
|
|
68 perpendicular | |
adj.垂直的,直立的;n.垂直线,垂直的位置 | |
参考例句: |
|
|
69 revolves | |
v.(使)旋转( revolve的第三人称单数 );细想 | |
参考例句: |
|
|
70 ellipses | |
n.椭园,省略号;椭圆( ellipse的名词复数 );(语法结构上的)省略( ellipsis的名词复数 ) | |
参考例句: |
|
|
71 applied | |
adj.应用的;v.应用,适用 | |
参考例句: |
|
|
72 complexity | |
n.复杂(性),复杂的事物 | |
参考例句: |
|
|
73 Uranus | |
n.天王星 | |
参考例句: |
|
|
74 Neptune | |
n.海王星 | |
参考例句: |
|
|
75 asteroids | |
n.小行星( asteroid的名词复数 );海盘车,海星 | |
参考例句: |
|
|
76 luminary | |
n.名人,天体 | |
参考例句: |
|
|
77 humble | |
adj.谦卑的,恭顺的;地位低下的;v.降低,贬低 | |
参考例句: |
|
|
78 swarm | |
n.(昆虫)等一大群;vi.成群飞舞;蜂拥而入 | |
参考例句: |
|
|
79 countless | |
adj.无数的,多得不计其数的 | |
参考例句: |
|
|
80 contemplate | |
vt.盘算,计议;周密考虑;注视,凝视 | |
参考例句: |
|
|
81 phenomena | |
n.现象 | |
参考例句: |
|
|
82 doctrine | |
n.教义;主义;学说 | |
参考例句: |
|
|
欢迎访问英文小说网 |