If now the astronomer observes the actual position of the asteroid in the sky, its right ascension and declination, and compares these with the position assigned to the planet by the law of gravitation when the attraction of Jupiter is ignored, the differences between the observed right ascensions and declinations and those computed upon the theory of undisturbed motion will measure the influence that Jupiter has had upon the asteroid, and the amount by which Jupiter has shifted it, compared with the amount by which the sun has moved it-that is, with the motion in its orbit-furnishes the mass of Jupiter expressed as a fractional part of the mass of the sun.
"A Text-Book of Astronomy"
George C. Comstock
This is now known to be well-nigh impossible, for every fragment which after the explosion moved in an elliptical orbit, as all the asteroids do move, would be brought back once in every revolution to the place of the explosion, and all the asteroid orbits must therefore intersect at this place.
"A Text-Book of Astronomy"
George C. Comstock
You know we've got to get back to that asteroid within two weeks.
"The World with a Thousand Moons"
Edmond Hamilton