... Optional: Quantum Physics . ... Energy Levels . ... Consider a proton inside the nucleus. ... Such nuclei, and heavy nuclei close to them in mass, are all on the brink of instability, and even without externally added energy, they find a way to get rid of some of their disruptive positive charge The forces on protons inside these nuclei resemble those on a bunch of marbles inside the "crater" of a volcano-shaped surface--smooth sloping sides outside, but a moderately deep crater on top ( drawing ). ...
... Files in red?history) . ... Positive Ions . ... In the 19th century it was well known that water in which salts were dissolved (or acids, or bases) conducted electricity, and that an electric current could separate such dissolved materials into their components. ... In 1898 Ernest Rutherford noted that the radiation seemed to contain two electrically charged components of opposite signs, steered by a magnet in opposite directions--positive "alpha rays" and negative "beta rays." ...
Hubble Observations Shed New Light on Jupiter Collision . Was it a comet or an asteroid? ... Their initial findings, combined with results from other space-borne and ground-based telescopes, shed new light on Jupiter's atmospheric winds, its immense magnetic field, the mysterious dark debris from the impacts, and the composition of the doomed comet itself. ... Hubble's ultraviolet observations show the motion of very fine impact debris particles now suspended high in Jupiter's atmosphere. ...