Word: dusts
(lookup in dictionary)
(lookup stats)
Dates: during 1980-1989
Sort By: most recent first
(reverse)
...Flagstaff, Ariz., Astronomers Lawrence Wasserman and Edward Bowell have calculated 40 points on the comet's route at which it will pass directly in front of a relatively bright star. During one of these passages, which are expected to last about 15 minutes, they hope to learn how dust is distributed in the coma by analyzing the starlight shining through it. At Mauna Kea Observatory in Hawaii, nearly 14,000 ft. above sea level, Astronomer Dale Cruikshank is using infrared photometry and imagery to measure the heat radiation from Halley's coma and the distribution of dust within...
...tasks, complementing and aiding one another every thrust of the way. Japan's two probes, Sakigake (Pioneer) and Suisei (Comet), between them will study the solar wind and examine the hydrogen cloud surrounding the comet. The Soviet Union's Vega 1 and Vega 2 will analyze the abundant dust motes and charged gases that envelop the comet's nucleus. Most remarkable of all, data and pictures from the Vega twins will enable European scientists to chart Halley's course precisely enough to allow their probe, Giotto, to come within about 300 miles of the nucleus, snapping thousands of photographs...
There are good reasons for this intensive scrutiny. To astronomers, a comet is a sort of flying museum stocked with precious artifacts from the very earliest moments of the solar system. They hope that by peering into Halley's cold heart and sniffing out the dust and gases that stream from its surface, they can discern the conditions that existed at the birth of the sun and the nine planets some 4.5 billion years ago. That in turn could reveal how common an occurrence the formation of planets around other stars may be, hence how likely it is that extraterrestrial...
...next big breakthrough came in 1950, when Fred Whipple, a Harvard astronomer, proffered a detailed model for the anatomy of a comet. In a delightfully evocative phrase, Whipple declared that comets are "dirty snowballs," dark conglomerates of mostly frozen water stippled 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...
...Langdell Library in the Law School, more than a half-million volumes are crumbling. At Countway Library in the Medical School, more than 150,000 books are falling to pieces. At Gutman Library in the Graduate School of Education, 50,000 books are turning to dust on the shelves. And at Widener Library, the flagship of the Harvard University Library system, more than 1 million books are crumbling...