A 6 min read Conodonts, the spiky phosphatic remains (bones and teeth composed of calcium phosphate) of tiny marine animals that probably appeared about 520 million years ago, were once among the most controversial of fossils....

A 6 min read (This passage is excerpted from material published in 1997) Whereas United States economic productivity grew at an annual rate of 3 percent from 1945 to 1965, it has grown at an annual rate of only about 1 percent...

A 10 min read Hurricane forecasters have difficulty determining maximum sustained surface-level winds. Reconnaissance aircraft usually obtain data from a flight level of 10,000 feet. However, in 1997, reconnaissance aircraft...

A 6 min read If early twentieth-century geologists and geo-physicists had heeded the fundamental axiom of the Greek philosopher Heraclitus. “Everything flows.” the sterile and sometimes bitter controversy that...

A 3 min read Meteorite explosions in the Earth’s atmosphere as large as the one that destroyed forests in Siberia, with approximately the force of a twelve-megaton nuclear blast, occur about once a century. The response of...

A 10 min read This passage is excerpted from material published in 1997. Is there a massive black hole at the center of our galaxy, the Milky Way? The evidence is inconclusive. (5) Just as the Sun’s mass can be determined,...