Friday, December 13, 2013
By BERNIE REIM
October will be a great month to enjoy New England's famous fall foliage. The changing leaves will slowly transform our verdant summer landscape into one of myriad and dramatic colors. The chemistry of the chlorophyll is very complex and interesting, and really makes you appreciate our precious trees and the vital function they play on Earth.
SKY GUIDE: This chart represents the sky as it appears over Maine during October. The stars are shown as they appear at 10:30 p.m. early in the month, at 9:30 p.m. at midmonth and at 8:30 p.m. at month’s end. There are no planets visible at map times. To use the map, hold it vertically and turn it so that the direction you are facing is at the bottom.
Sky Chart Prepared by George Ayers
Day length and temperature both play roles in this seasonal change. One is caused by the tilt of the Earth, which causes the seasons as our two hemispheres slowly take turns facing the sun more directly. Weather and temperature changes are caused by differential heating of our life-sustaining atmosphere by the sun. So this annual and colorful ritual really reminds us of our Earth's continual and transforming connections with our sun, which is in turn interacting with all of the stars in our galaxy.
There will be several interesting new highlights in October as the nights slowly get longer and colder while we head toward winter. There will be two meteor showers, two comets to find in the morning sky, the planet Uranus at its best for the year, and some nice conjunctions.
The Southern Taurid meteors will peak before dawn on the 10th. You can expect only about five meteors per hour, which is just above the background rate of three or four stray meteors every hour that are not associated with any shower. However, the Southern Taurids move slower than typical meteors, which make them better subjects for viewing and photography.
The more famous shower this month is the Orionid meteor shower, caused by Halley's Comet. The Eta Aquarid shower on May 4 is also caused by this famous comet. The Orionids will be partly washed out by the moon, since their peak on the 21st is only three days after the full moon. If it is clear that night, it will still be worth it to see and appreciate these tiny, sand grain-sized pieces of Halley's Comet streaking into our upper atmosphere at 40 miles per second.
The much heralded Comet ISON will be visible around 4 a.m. It is very close to Mars now in Leo, not just in line of sight but in actual proximity. ISON will not become as bright as originally thought, but it will probably still become a naked-eye comet by November or December at the latest. It is similar to Comet Kohoutek in that regard. Being a first-time comet, it gives off a lot of volatiles when it enters the solar system, making it difficult to predict later what that rate of brightening will be.
The other pre-dawn comet in October is Comet Encke. Discovered by German astronomer Johann Encke in 1818, this is one of the shortest period comets we have at only 3.3 years. However, based on the geometry of the sun, Earth and comet, it shows up much better every three orbits. This will be its best appearance in a decade. You can see it in Gemini, Cancer and Leo, not far away from Comet ISON and Mars. It should brighten from about 11th to seventh magnitude, similar to ISON.
The planet Uranus, discovered by William Herschel on March 13, 1781, will be at its best for the year in October as it reaches opposition on the third in the constellation of Pisces. Our seventh planet will be so bright that you will be able to see it without binoculars or a telescope. It will reach 5.7 magnitude. The human eye can see stars and objects as faint as sixth magnitude from a dark sky. Uranus will rise at sunset and not set until sunrise. This is called opposition and is always the best time to view a superior planet because it will also be closest to Earth, and largest and brightest in our skies at that time.
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