Word: comas
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Dates: during 1980-1989
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...most dramatic display so far. As the comet neared its Feb. 9 perihelion, its closest approach to the sun (about 55 million miles), the searing solar rays caused increasing amounts of material to evaporate from its icy surface. Eventually the comet's enveloping gas cloud, or coma, grew to more than 12.5 million miles across, temporarily becoming the largest object in the solar system...
...Bulow was convicted in his first trial for attempting to murder his millionaire wife Sunny by giving her coma-inducing insulin injections...
...with rocky fragments, dust particles and trace elements. As one of these snowballs swoops toward the sun, said Whipple, solar radiation begins to vaporize ice and frozen gases on the comet's sunward surface by a process called sublimation. The gases, carrying dust with them, form a light-reflecting coma that makes the comet visible from earth...
Many other aspects of cometary theory have since been refined or expanded. By studying the spectra of light emitted from molecules broken down in the gaseous coma, scientists have estimated that a comet's nucleus consists of two-thirds water, one-fifth dust (particles averaging one-thousandth the width of a pinhead) and the rest a mixture of methane, ammonia, carbon dioxide and trace elements...
When a comet is still as far away as 5 AU from the sun, about the distance of Jupiter, its most volatile material begins forming a coma that reflects light. By the time the most powerful telescopes first catch a glimpse of a comet, the coma already obscures the nucleus beneath. For every revolution a typical comet makes around the sun, its diameter is estimated to shrink about 6 ft. Hence the original size of the comet, the length of its orbit and how close it gets to the sun will determine its life-span. Astronomers estimate that Halley...