The third body is taken to be so small that it does not affect the orbits of the larger ones.
Such large bodies would affect the orbits of exocomets in the Beta Pictoris system, giving astronomers clues to their presence and movement.
Therefore, tidal interaction mostly affect the orbits of relatively close binaries, unless the eccentricities are high and/or the stellar radii are large.
In 1964, Fred Whipple, who popularised the famous "dirty snowball" hypothesis for cometary structure, thought that a "comet belt" might be massive enough to cause the purported discrepancies in the orbit of Uranus that had sparked the search for Planet X, or, at the very least, massive enough to affect the orbits of known comets.
And since Newton's theory could hardly be wrong, the only answer that made sense was that there must be another small, invisible companion affecting the orbit of Mercury.
1906 Wealthy polymath Percival Lowell speculates on the possibility of "Planet X", a ninth planet affecting the orbits of Neptune and Uranus.
The finding allows astronomers to more accurately gauge Pluto's mass, proving that it is too small to have affected the orbits of other planets.
At first, astronomers reckoned it was roughly as massive as Earth, based on calculations about how they presumed it was affecting the orbits of Uranus and Neptune, the seventh and eighth planets from the sun respectively.
Changes in neutral density, affecting the orbits of space debris objects, can be very dangerous because it makes it more difficult to predict their position, making it very important to secure better predictions by improving the current models (Klinkrad 2010; Lewis et al. 2011).
