National Geographic : 1957 Dec
816 University of Chicago Comet Flies a Glowing Tail Millions of Miles Long First sighted late last summer, Mrkos-1957d flashed brighter than any comet seen in recent years. The visitor is named for a Czech astronomer; the letter "d" designates it as the fourth comet recorded this year. As Mrkos approached the sun, radiation pressure caused its long tail of luminous gases to stream away in the opposite direction, making it seem to stand on its head in the sky. The word comet comes from the Greek kometes, meaning long-haired. most people, at least initially, find it difficult to visualize these star groups with flesh and sinew, in the classic manner, as artists have represented them on the new map. Moreover, the difficulty is enhanced by a great variation in apparent brightness among key stars in many groups. Despite viewing difficulties, most moderns prefer to visualize sky pictures in the pat terns established by the ancients. To do otherwise, they feel, would divorce the ob server from much of the legend, romance, and mystic appeal of our heavens. Other persons take the old star groups and convert them with a creative eye into new pictures. Whatever you may behold in the constella tions, an ability to identify them is invalu able. No one who knows them well is lost so long as he can see the night sky. Directions are apparent, and he may even make a shrewd guess as to the approximate time. For a navi gator, of course, knowledge of the guidepost groups is essential. They help him locate the 55 stars used in celestial navigation. Whence Came the Christmas Star? December's advent always revives among sky watchers a favorite topic: the possible origin of the Christmas star that led three Wise Men to the Prince of Peace. One school of thought believes the star was of miraculous origin; another that the Bibli cal reference is symbolic rather than literal. A third holds that an astronomical explana tion is possible. Astronomers know that Jupiter and Saturn approached one another three times in the year 7 B.C. During such an event, a "close con junction," they might have seemed to merge into a single blazing object. Man has so toyed with his calendar that it is conceivable Christ was born in 7 B. C. Therefore, some authorities believe the Wise Men saw a con junction of planets, not a star. Still others think the star may have been a nova, or exploding star, or perhaps a super nova. The prefix "super" is reserved for in conceivably powerful stellar explosions of the kind that have occurred three times in the Milky Way in the past 900 years. Briefly such a cataclysm may give off more light than all the stars in a galaxy combined. A third explanation holds that the Wise Men saw a comet. Advocates of this theory point out that the tail of the comet may in deed have made the "star" seem to stand above Christ's manger. Though men may differ in their speculation about the Christmas beacon, though they may disagree on the imagery of the heavens, each feels the same awe, wonder, and humility at the beauty of a star-filled night. Give the watcher his darkened hilltop, touch off the fires in the abode of the gods, and his cares vanish in a surge of the spirit.