Comet Hale–Bopp
Comet Hale–Bopp was observed intensively by astronomers during its perihelion passage, and several important advances in cometary science resulted from these observations. The dust production rate of the comet was very high (up to 2.0 kg/s), which may have made the inner coma optically thick. Based on the properties of the dust grains—high temperature, high albedo and strong 10 μm silicate emission feature—the astronomers concluded the dust grains are smaller than observed in any other comet.