the satellites switched orbits and decided that the satellites must have densities of less than 0.7 grams per cubic centimeter. This is considerably less than the density of the other satellites and is less than the density of pure ice.Apparently, these satellites are merely piles of icy debris, with some 30 percent of their structure consisting of empty space. Is it possible that these ...
that make up matter.Ordinary matter is not very dense. Water, for instance, has a density of one gram per cubic centimeter. That is because the really dense part of the atom, the proton at the center, is kept away from other protons by electrons.Some elements have nuclei consisting of many protons and neutrons all clinging together. These nuclei are kept apart by electrons but even so such ...
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