| The Connection between Comets and Meteors |
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| Written by Jim Stepp | |
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Edmond Halley was the first person to recognize that comets were periodic. This discovery was made in 1705 after he had computed parabolic orbits for 24 comets observed from 1337 to 1698. His analyses of the list revealed the comets of 1531, 1607, and 1682 moved in almost identical orbits and were separated by intervals of roughly 75 years. From this information, he predicted the comet would next appear in 1758. Halley died in 1742. The comet that now bears his name was recovered on 1758 December 25, by Johann Georg Palitzsch, a German farmer and amateur astronomer. Following the return of 1758-1759, astronomers began trying to link Halley's comet to comets seen prior to the 1531 appearance. Ultimately, 23 previous appearances were identified, indicating the comet had been seen at every return going back to the year 240 BC. When comets return to the Sun, the Sun’s heat warms the surface of the comet and produces geyser type fountains that shoot material into space. This material and the dust that gets blown out into space with it produces the tails we associate with comets. Once in space this material closely follows the orbit of the comet. Occasionally the Earth passes through these streams of material and a meteor shower occurs. Sometimes the Earth just glances the edge of the material stream or passes through a less dense stream and we see what are called minor meteor showers. Minor meteor showers produce anywhere from 2 or 3 meteors per hour up to 10 to 15 meteors per hour. On other occasions the Earth passes near the center of a material stream or goes through a denser portion of a material stream and we have a major meteor shower. The amazing things about meteors are their size. The bright flashes we see at night are usually caused by sand sized particles hitting the Earth’s atmosphere at 30 miles per second. Some meteors are larger and even brake up when they enter the Earth’s atmosphere. Between October 4 and October 13 a total of 7 minor meteor showers reach their peak activity. If you happen to be outside on any of these nights keep an eye on the sky. Most of these meteor showers are located towards the north of our area, so look in that area of the sky. During these nights there is a potential to see between 4 and 20 meteors per hour. The best viewing time is after midnight. For more information about comets and meteors, please go to: http://comets.amsmeteors.org/ The Sky’s Over Northern Maine 09/29 Sunrise 6:28 a.m., Sunset 6:16 p.m. 09/30 First Quarter Moon 7:04 a.m. 09/30 Mercury at aphelion-farthest distance from the Sun (43,391,838 miles or 69,817,468 km) 10/04 USSR’s Sputnik 1 becomes the first man-made object to orbit the Earth (1957) 10/04 Eta Cetids Meteor Shower peaks (5/hour) 10/05 October Cetids Meteor Shower peaks (5/hour) 10/06 Sunrise 6:37 a.m., Sunset 6:02 p.m. 10/06 Moon at perigee - closest to the Earth (222,134 miles or 357,415 km) 10:13 a.m. 10/06 October Cygnids Meteor Shower peaks (5/hours) 10/08 Arietids Meteor Shower peaks (3-5/hour) 10/09 Draconids Meteor Shower peaks (15/hour) 10/10 Delta Aurigids Meteor Shower peaks (5/hour) 10/13 Northern Piscids Meteor Shower peaks (5-6/hour) 10/13 Sunrise 6:47 a.m., Sunset 5:49 p.m. 10/16 Saturn close to the moon 10/19 Astronomy Program - Topic to be announced 6:15 p.m. in the Campus Center. 10/19 Moon at apogee-closest to the Earth (252,363 miles or 406,052 km) 5:35 a.m. 10/20 Sunrise 6:57 a.m., Sunset 5:36 a.m. |
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