The first 800 million years: environmental models for early Earth.
Space exploration has changed our views not only on the properties of celestial bodies and the interplanetary medium but also our perspective on the formation of such bodies, including the Earth. However, on few points do the new hetegonic insights approach certainty. More appropriately, they can be said to raise physically meaningful questions and to decrease the degrees of freedom allowable in any given scenario, which necessarily extends into the early history of the planetary crust, ocean and atmosphere. An attempt is made here to outline the basic schemes envisaged in modern studies of the origin of the Earth and the ramification of consequences for its early evolution that currently appear allowable and supported by observation.a new study finds. The birds were raised for their colorful plumage hundreds of miles from their native jungles.

With their brilliant red, yellow and blue plumes, scarlet macaws are likely the best-known parrots of the New World. These birds normally range from South America to eastern coastal Mexico and Guatemala.

On May 5, 1961, Alan Shepard became the first American in space when he piloted the Mercury capsule Freedom 7. His sub-orbital journey lasted 15 minutes. Like most children who grew up in the early era of space flight, I remember this moment well.

The flight was extra special for me because my dad, Arthur L. Levine, worked for NASA. As a human resources administrator, he recruited John Glenn, who in 1962 became the first American to orbit Earth. My