Comets, when near the sun, are greatly affected by the disturbing attraction of large planets, and especially of the most massive of them all, Jupiter. The effect of this disturbance is to change the form of their orbits, with the not infrequent result that the latter are altered from apparent parabolas into unquestionable ellipses, and thus the comets concerned are said to be “captured,” or made prisoners to the sun, by the influence of the disturbing planet. About twenty small comets are known as “Jupiter's Comet Family,” because they appear to have been “captured” in this way by him. A few others are believed to have been similarly captured by Saturn, Uranus, and Neptune.