- Messier 55 (also known as M55, NGC 6809, or Specter Cluster) is a globular cluster in the south of the constellation Sagittarius. It was discovered by Nicolas Louis de Lacaille in 1752 while observing from what today is South Africa. Starting in 1754, Charles Messier made several attempts to find this object from Paris but its low declination meant from there it rises daily very little above the horizon, hampering observation. He observed and catalogued it in 1778. The cluster can be seen with 50 mm binoculars; resolving individual stars needs a medium-sized telescope.
- Rutherford model (Wikipedia)
The Rutherford model was devised by Ernest Rutherford to describe an atom. Rutherford directed the Geiger–Marsden experiment in 1909, which suggested, upon Rutherford’s 1911 analysis, that J. J. Thomson’s plum pudding model of the atom was incorrect. Rutherford’s new model for the atom, based on the experimental results, contained new features of a relatively high central charge concentrated into a very small volume in comparison to the rest of the atom and with this central volume containing most of the atom’s mass; this region would be known as the atomic nucleus. The Rutherford model was subsequently superseded by the Bohr model.