Bücher von David A. J. Seargent

Naked-eye comets are far from uncommon. As a rough average, one appears every 18 months or thereabouts, and it is not very unusual to see more than two in a single year. The record so far seems to have been 2004, with a total of five comets visible without optical aid. But 2006, 1970, and 1911 were not far behind with a total of four apiece. Yet, the majority of these pass unnoticed by the general public. Most simply look like fuzzy stars with tails that are either faint or below the naked-eye threshold. The ¿classical¿ comet ¿ a bright star-like object with a long flowing tail ¿ is a sight that graces our skies about once per decade, on average. These ¿great comets¿ are surely among the most beautiful objects that we can see in the heavens, and it is no wonder that they created such fear in earlier times. Just what makes a comet ¿¿great¿¿ is not easy to define. It is neither just about brightness nor only a matter of size. Some comets can sport prodigiously long tails and yet not be regarded as great. Others can become very bright, but hardly anyone other than a handful of enthusiastic astronomers will ever see them. Much depends on their separation from the Sun, the intensity of the tail, and so forth.

Strange behavior of comets, such as outbursts and schisms, and how asteroids can temporally act as comets are discussed, together with the possible threat of Centaurs-class objects like the Taurid complex. Recent years have seen the distinction between comets and asteroids become less prominent.

As new discoveries complicate the scientific picture of the universe, the evolving theories about the nature of space and time and the origins and fate of the universe threaten to become overwhelming.

Topics include anomalous lights, anomalous sounds, spectacular effects of cloud illumination by the Sun or Moon, lightning phenomena, electrophonic sounds of lightning, aurora and meteors, tornado and whirlwind phenomena on Earth and Mars, usual atmospheric effects, mirages, and the possible astronomical influences on cloud and climate.

Within our own Solar System, odd facts such as the apparent reversal of the Sun in the skies of Mercury, CO2-driven fountains of dust on Mars, possible liquid water (and perhaps primitive life!) deep within the dwarf planet Ceres, and a variety of odd facts about the planetary moons are all discussed.