Three distinct observations suffice to determine the orbit of a planet completely, but it is well to have the three observations as far apart as possible so as to minimize the effects of minute but necessary errors of observation.

It did not follow that I had crossed the orbit of the Moon; and if I had, she was at that time too far off to exercise a serious influence on my course.

To be sure, I have only once in the time computed a parabolic orbit; but it seems to me that I know no more in general.

If I should fail to come near enough to the goal of my journey, and yet should go on into space, or if, on the other hand, I should stop short, the Astronaut might become an independent planet, pursuing an orbit nearly parallel to that of the Earth; in which case I should perish of starvation.

We shall then know our universal function and find our universal orbit.

In either case, I should be dangerously far from Mars, beyond his orbit or within it, at the time when I should come into a line with him and the Sun; or, again, putting the same mischance in another form, behind him or before him when I attained his orbit.

I drew, therefore, in the first place, a globe to represent the Earth, traced its orbit round the Sun, and placed a crescent Moon at some little distance, indicating its path round the Earth.

He conjectured that this might prove to be true for arcs at all parts of the orbit, and to test this he divided the orbit into 360 equal parts, and calculated the distances to the points of division.

Infinite skill is not exhausted nor concentrated in the structure of a firmament, in drawing the orbit of a planet, in laying the strata of the earth, in rearing the mountain cone.

"Then where does it go?" "As Gene said yesterday," explained Zip, "it's moving too fast to enter an orbit around the Earth, so Gene steered it into a course around the sun.

But even he retained epicycles and excentrics, and could not explain the unequal orbits of planetary motion.

The Moon thought she knew her own orbit well enough; but when she saw the curve on Zuleika's cheek, she was at a loss: "And since round lines are drawn My darling's lips about, The very Moon looks puzzled on, And hesitates in doubt If the sweet curve that rounds thy mouth Be not her true way to the South.

Miss Penelope was in her accustomed place, which she could no more get away from than a planet could leave its orbit.

O, thou cloudless sun, and ye far-distant stars, in all your journeyings in light, have ye discovered no blessed intelligence who called you into being, lit up your fires, marked your orbits, wheels you in your courses, around whom ye roll, and whose praises ye silently celebrate?

"We've just passed the orbit of Neptune, sir," announced the pilot.

He had plotted the orbit of Mars, the thrust and direction of the power units on G670, the speed of the red planet in its course and its rotation, the anticipated acceleration of the asteroid, and the time delay involved in making adjustments to its course.

7, one of the satellites may either fall into the sun or pursue an elliptical orbit and become periodical, while the principal star may preserve a parabolic orbit, and make but one appearance.

If I succeeded in this, I should reach the orbit of Mars at the point and at the moment of opposition, and should attain Mars himself.

The practical effect of his clearing of the "second inequality" was to refer the orbit of Mars directly to the sun, and he found that the area between successive distances of Mars from the sun (instead of the sum of the distances) was strictly proportional to the time taken, in short, equal areas were described in equal times (2nd Law) when referred to the sun in the focus of the ellipse (1st Law).

Much, too, as we are inclined to ridicule the astronomy of the ancients because they made the earth the centre, we should remember that they also resolved the orbits of the heavenly bodies into circular motions, discovered the precession of the equinoxes, and knew also the apparent motions of the planets and their periods.

This at least can not be doubted, That our globe will one day roll Cold and lifeless thro' its orbit, Like a corpse without its soul.

While the earth swings round its orbit once a year, and turns on its axis once in twenty-four hours,while the tide ebbs and flows twice daily, and the seasons come and go in rotation, every atom changes its relations to every other atom every moment.

It is almost time now that the poor came up again, for a quarter of a century has gone since they were last in fashion, and men's collars and women's skirts have run their full orbit since.

"The pit," whispered Flip; "it's safe on the other side," she added, cautiously skirting the orbit of the great eye, and leading him to a sheltered nest of bark and sawdust.

They can name every spot from Peru to El Arish, Except just the bounds of their own native parish; And they study the orbits of Venus and Saturn, While their home is resign'd to the thief and the slattern.