At first glance, asteroids may seem like run-of-the-mill space rocks, but these ancient solar system remnants come in all shapes, sizes and flavors
Comets
For millennia, the sight of a comet elicited fear and awe. Ancient astronomers believed comets foretold the death of princes and the outcomes of wars. Modern astronomers know comets are the ice-clad leftovers from the material that formed our solar system billions of years ago.
Meteoroids
Meteoroids are the true space rocks of the solar system. No larger than a meter in size (3.3 feet) and sometimes the size of a grain of dust, they are too small to be considered asteroids or comets, but many are the broken pieces of either. Some meteoroids originate from the ejected debris caused by impacts on planets or moons.
Diffusion means that particles travel from a higher concentration to a lower concentration region before balance is achieved. The semi-permeable membrane is present in osmosis, so that only solvent molecules can travel freely to equalize the levels.
