. Astronomy for high schools and colleges . f the comet is simply a continuation of thecoma extending out to a great distance, and always di-rected away from the sun. It has the appearance of astream of milky light, which grows fainter and broader A8PECT OF COMETS. 389 as it recedes from tlie liead. Like the coma, it shades offso gradually that it is impossible to fix any boundaries toit. The length of the tail varies from 2° or 3° to 90 ormore. Generally the more brilliant the head of the comet,the longer and brighter is the tail. It is also often brighterand more sharply defined at one edge
. Astronomy for high schools and colleges . f the comet is simply a continuation of thecoma extending out to a great distance, and always di-rected away from the sun. It has the appearance of astream of milky light, which grows fainter and broader A8PECT OF COMETS. 389 as it recedes from tlie liead. Like the coma, it shades offso gradually that it is impossible to fix any boundaries toit. The length of the tail varies from 2° or 3° to 90 ormore. Generally the more brilliant the head of the comet,the longer and brighter is the tail. It is also often brighterand more sharply defined at one edge than at the other. The above description applies to comets which can boplainly seen by the naked eye. After astronomers beganto sweep the heavens carefully with telescopes, it wasfound that many comets came into sight which wouldentirely escape the unaided vision. These are called tel-escojpio comets. Sometimes six or more of such comets arediscovered in a single year, while one of the brighter classmay not be seen for ten years or
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