Discusses a theory suggesting that large-scale extinctions of marine animal families occur in cycles of 26 million years. Research methodology consisted of analyzing and charting fossil records showing the decline and disappearance of these animals over the past 250 million years. Other theories are considered. (BC)

Discusses conflicting theories that explain how and why bombardment by comets spells periodic disaster for life on earth. Dislodgment of comets occurs from a vast cloud that envelops the solar system by gravitational forces of either a companion star of the sun or a dust cloud. (BC)

Highlights scientific accomplishments in 1981. Focuses on space sciences, medicine, geology, chemistry, physics, zoology, paleontology, environmental problems, and genetics including such topics as the Space Shuttle, Mount St. Helen's endangered species, genetic engineering, and the scientists associated with these accomplishments. (JN)

Highlights advances/discoveries (and scientists responsible for them) in various science areas during 1983: space science (shuttle flights, Russia); astronomy (infrared satellite, inflationary universe); physics (W/Z particles); chemistry (carbon bonding); environment (acid rain, dioxins, El Nino); bioscience (chemical signals); paleontology…