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The Sky This Month - October 2013

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Written by Gary Boyle on
Post Date: 
Tue, 2013/10/01

The Sea Goat

With shorter days we see the sun now set before 7 p.m. locally and those pesky mosquitoes are all but gone. When you add these factors, October is a great month to be outdoors and doing what we all love to do. We first start off with the sinking Milky Way in the south. The famous Teapot of Sagittarius is touching the horizon around midnight but you still have a good four hours at the beginning of the month before that occurs. If you have never photographed the Milky Way around this area, try it over the next week before the moon creeps back into the sky and washes out the stellar portrait. You would be very surprised the collection of objects the lens can capture in about 30 seconds at ISO1600.

Once you are done with Sagittarius, move over one constellation to the left and enjoy a few choice objects in Capricorn the Sea Goat and surrounding area. This semi-triangular shaped collection runs about the middle of the pack and 40th overall in size. Capricorn is also one of Ptolemy’s original 48 constellations that he produced from countless observations.

The brightness of the constellation members run between 3rd and 4th magnitudes making it an ordinary asterism. However its brightest star Deneb Algedi (Delta) lies 39 light years distant. At its peak, this sun shines at magnitude 2.81 but drops a quarter of a magnitude every 24.5 hours This is because it is an eclipsing binary, much like the star Algol is in the constellation Perseus. Some astronomers have very keen eyesight and would see this tiny change.

Alpha Capricornus is a beautiful double star system consisting of a yellow magnitude 4.2 star located some 1,600 light years from us and an orange magnitude 3.6 star only 120 light years away. Although these two can be seen naked eye and with binoculars, a telescope will show each is a close double.

One of the few globular clusters associated with Capricorn is M30. This dense snowball of stars is about 26,000 light years distant and measured to be some 90 light years wide. M30 holds not less than a dozen variable stars. If you partake in the yearly Messier Marathon when an observer can theoretically observe all 110 objects in a single moonless night. It is a time when the solar glare does not hide these objects. So if you are a marathoner, you know that M30 is the last object on the list as you are battling morning twilight. At magnitude 8.4, any sky lightening would not be welcomed. As a whole, Capricorn contains a good number fainter spiral galaxies as well as irregular lenticular galaxies – those that have no structure to it and appear in disarray. 

Well August was the month for things that explode. First we learned about a star in our galaxy that underwent a nova in the constellation Delphinus on August 12. This was the flash from a young neutron star’s outer envelope of gas stolen from a close old red giant star. Around this same time period supernova SN2013ev was discovered in the tiny galaxy IC 1296 located next to M57 – the Ring Nebula. The galaxy is located some 220 million light years distant while the Ring Nebula is only 2,500 light years away. If the night is clear, try photography as the nova is around 15th magnitude or fainter.

The Draconid meteor shower is set to peak on October 8th. Unlike the Perseids and mostly all other meteor shower where the rate of meteors seen per hour is pretty well known, the Draconids are somewhat unpredictable. It might be worth your while bundling up and heading out to see them. The IMO states this shower can produce anywhere from a scant 10 to 20 meteors up to storm values of hundreds per hour for a short burst. Since this is not a return year for the parent comet, the number should be low but surprises can happen anytime.

The weeks are now ticking down till we witness the Comet ISON show. Still at an estimate 14th magnitude, the comet is only two degrees north of Mars and closing in. Even though the red planet makes a great marker, you will need photography to catch its faint photons compared the predicted daytime visibility in December. The predictions are still on the low side but only time will tell.

Speaking of planets, Jupiter is up in the NE skies around 1 a.m. local time. Except for the moon, this gas giant is the brightest object in the sky and cannot be missed. There will be a dramatic view of a double shadow of the moons Io and Europa on the morning of the 12 at 3:30 EDST. Don’t forget to try and catch the zodiacal light seen in the east before sunrise.

We now pretty well say farewell to Saturn as it hugs the western horizon and moving into the solar glare. Even if you have a clear view to the west, Atmospheric distortion will yield a very fuzzy image. New Moon occurs on October 4 at 20:35 EDT while the full Hunter’s Moon washing out the sky on the 18th at 19:38 EDT.

Until next month, clear skies everyone.

Gary Boyle