Scientific American Magazine

The artificial satellites are man's first venture into experimental celestial mechanics. An account of how the first satellite's orbit was determined, and how our knowledge of this orbit can be applied

Although they are associated with the Antarctic, it is not widely realized how well they are adapted to this formidable environment. For example, a penguin can fast 40 days in order to raise its young

It is a substance found in the blood, the brain, certain tumors, the clam, the octopus, jellyfish and nettles. Discovered only 10 years ago, it is presently a frontier of physiological research

If man can tame the reactions in which the nuclei of atoms are fused rather than split, he will have an almost limitless source of energy. The problem is now being attacked in laboratories all over the world

It is known that this large-boned man and Homo sapiens lived at the same time. The author presents a hypothesis on where the two kinds of men originated and how they came in contact

The last great physicist of the era before the discovery of X-rays, radioactivity and subatomic particles, he is best remembered for his demonstration of the connection between electromagnetism and light

The status of the problem: Tooth enamel is not a rocklike substance but a living tissue. It is sometimes invaded by bacteria, depending on heredity, nutrition and other factors influencing the individual

This tiny fresh-water animal can be cut into as many as eight pieces, each of which then grows into a complete individual. Recent studies have illuminated how it grows and regenerates