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October Skies


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October Skies - by Dick Cookman

10/5/2012

Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, October Moon

Focus Constellations: Perseus, Cassiopeia, Cepheus, Camelopardalis, Ursa Minor, Ursa Major, Draco, Lyra, Cygnus, Aquila, Aquarius, Pegasus, Pisces, Aries, Andromeda

Comet Journal

On Sept. 21st Vitali Nevski and Artyom Novichonok detected a new 18th magnitude comet in Cancer with the 15.7-inch (0.4-meter) reflecting telescope of the International Scientific Optical Network (ISON), near Kislovodsk, Russia. Examination of previous photographs of the region were utilized to trace its path since December, 2011. This data enabled scientists to determine that it probably originated in the Oort Belt. The new comet has been designated as Comet C/2012 S1 (ISON) and may reach naked eye visibility in Leo in October, 2013. It is then expected to be a Sun grazer that has the potential to outshine the Moon and light up daytime skies near perihelion on Thanksgiving, 2013. In January, 2014 it will pass less than 40 million miles of Earth on its outward trip.

Meanwhile, Comet 2011 F1 (Linear) is at 10th magnitude and is slightly above the western horizon below Serpens Caput shortly after sunset. It may brighten to 9th magnitude in predawn skies as it approaches perihelion in January, 2013.

Comet C/2011 L4 (PanSTARRS), which may reach naked eye visibility in the winter, is approaching 11th magnitude as it moves eastward between Scorpius and Lupus. It will appear in northern morning skies prior to perihelion in March, 2013 then move northward in the Spring.

Martian Landers

On August 29th Curiosity departed from its landing site (Bradbury Landing) in Gale Crater on its way to Glenelg, its first major destination almost 400 meters (0.25 mi.) eastward where three types of terrain meet at the base of Mt. Sharp, the 3 mile high mountain at the center of the crater. During the journey to Glenelg the rover continued to test out its various systems and by Sept. 19th (Sol 43) reached the halfway point and proceeded to a nearby football sized rock called Jake Matijevic after a deceased JPL scientist who was integral to Martian exploration missions in the last 30 years.

The rover touched the rock with a spectrometer to determine its elemental composition and used an arm-mounted camera to take close-up photographs. Both the arm-mounted Alpha Particle X-Ray Spectrometer and the mast-mounted, laser-zapping Chemistry and Camera Instrument will be used for identifying elements in the rock. This will allow cross-checking of the two instruments. After completing examination on the 24th, the rover proceeded over the alluvial fan between Mt. Sharp and the rim of Gale Crater. The fan is at the outlet of Peace Vallis, a canyon dissecting the rim of the crater. On the 27th, Curiosity reached a rock outcrop called Hottah made up of a slab of tilted sedimentary conglomerate rock comprised of sand and pebble size particles. Most are rounded indicating significant stream transport by an ancient stream which flowed into the crater from a location beyond the rim. Knee deep streams on Earth flowing at 3 feet per second produce deposits with gravel of similar size and shape.

On Sept. 30th, the rover used two tools at the end of its arm to inspect two targets on an angular rock called Bathurst Inlet, then moved on October 1st - 3rd (Sol 58) to a wind blown area called Rocknest which contains a ripple of sand where its sampling tools will be tested and samples examined by its analytical instruments.

At the end of August Opportunity deviated from its southward journey on a shelf on the western margin of Endeavor Crater between the crater and Cape York, the elongated ridge stretching one half mile north-northeastward from Botany Bay. The new target was an outcrop of rock called Matijevic Hill on the edge of Cape York.

A short westward drive allowed Opportunity to approach the outcrop by Sol 3063 (Sept. 4, 2012) where imagery revealed a dense accumulation of small spherical objects as much as one-eighth of an inch (3 millimeters) in diameter at a location called Kirkwood. Although initial appearances reminded investigators of the iron rich, hematite bearing "blueberry" concretions found at the landing site in 2004, these present a puzzle requiring further investigation as they differ in concentration, structure, and composition.

On 3071 (Sept. 13, 2012), the rover moved to large light-toned block of exposed rock which revealed hydrated minerals in previous imagery. Following investigations here, Opportunity will probably move to a nearby extensive pale-toned outcrop in an area of Cape York where orbital observations show signs of clay minerals.

Meteor Showers

The 3rd quarter Moon which rises after midnight will not interfere with evening viewing of the Draconid Meteor shower on the 8th or the Southern Taurids on the 10th. The former is a minor shower comprised of debris from Comet 21P/Giacobini-Zinner and produces occasional storms, the last of which was in 1998. The latter is also a minor shower and results from debris scattered along the orbit of Comet Encke. It often produces numerous fireballs. The best shower or the month is the Orionids during the 20th to 24th. Its progenitor is Comet 1P/Halley and it generally produces about 20 meteors per hour in dark skies. According to Alan MacRobert in "Sky & Telescope," there were 40 to 70 or more meteors per hour from 2006 to 2009.

Planet Plotting

Mercury (-0.4 in Virgo) and Saturn (+0.7 in Virgo) are difficult to view in early evening skies in early October and sink into the glow of sunset in the middle of the month. Saturn starts October with a 20° separation from the Sun and closes the gap by the 25th when it is at solar conjunction. Mercury doubles its distance from the Sun during October as it moves in Libra and is 24° away at greatest eastern elongation on the 26th. Both set at very low angles to the southwestern horizon and despite their separation from the setting Sun they are barely visible above the horizon. Mars (+1.2 in Libra) sets two hours after the Sun throughout October as its eastward motion keeps pace with progressively earlier sunsets. Uranus (+5.8 in Pisces) and Neptune (+7.9 in Aquarius) are high in the southeast after sunset and are visible most of the night.

Jupiter (-2.5 in Taurus rises in mid-evening on the 1st and after sunset on the 31st. It dominates the southeastern evening sky and is high in the predawn southern sky. Venus (-4.1 in Leo) dominates the eastern sky before sunrise and provides a brilliant nightlight for early risers.


Planet Constellation Magnitude Planet Passages
Sun Virgo -26.8  
Mercury Virgo, Leo -0.4 to -0.2 Saturn, 3°S, 10/6, 3AM EDT, Max Eastern Elongation 10/26, 6PM EDT
Venus Leo, Virgo -4.1 to -4.0  
Mars Libra, Scorpius +1.2  
Jupiter Taurus -2.5 to -2.7  
Saturn Virgo +0.7 to +0.6 Mercury, 3°N, 10/6, 3AM EDT, Solar Conjunction, 10/25, 5AM EDT
Uranus Pisces +5.7  
Neptune Aquarius +7.9  

October Moon

The New Moon on September 15th was the beginning of Lunation 1110 which ends with the New Moon at 8:02 AM EDT on October 15th. Lunation 1110 lasts 29.41 days.

The Full Moon on October 29th at 3:49PM EDT is part of Lunation 1111 which ends with the New Moon of November 13th. It was the "Hunter's Moon" to Colonial Americans who took advantage of its light to hunt in the stubble of the fields harvested in the previous month.

Celts referred to October's Full Moon as the "Harvest Moon" and Chinese call it the "Kindly Moon". Medieval English who hunted and dressed their prey in the light of the Moon named it the "Blood Moon" and northern Michigan Anishnaabe (Chippewa and Ojibwe) call it °Binaakwe-giizis" (Falling Leaves Moon).

Apogee, when the Moon is farthest from Earth occurs on the 4th at 8:43PM EDT. The Moon will be at a distance of 63.53 Earth Radii or 251,775 miles. Perigee is on the 16th at 9PM EDT when the Moon will be at 224,111 miles or 56.55 Earth radii slightly more than 36 hours after New Moon. Tides will be exceptionally high because closest lunar proximity and New Moon almost coincide. New and Full Moon phases produce "Spring tides" which are the highest tides of the month because the combined gravity of the Moon and Sun is exerted on the Earth along the same line. During other phases the Moon and Sun deform the Earth in differing directions producing lower high tides.

Planet Constellation Magnitude Moon Passage Moon Phase/Age
Sun Virgo -26.8 8:02AM EDT, 10/15 New ~ 0 days
Mercury Libra -0.2 1.3°N, 10PM EDT, 10/16 Waxing Crescent ~ 0.94 days
Venus Leo -4.1 6.0°S, 3PM EDT, 10/12 Waning Crescent ~ 26.70 days
Mars Scorpius +1.2 2.0°N, 9AM EDT, 10/18 Waxing Crescent ~ 3.04 days
Jupiter Taurus -2.5 0.9°S, 5PM EDT, 10/5 Waning Gibbous ~ 19.78 days
Saturn Virgo +0.7 4.5°SSW, 10PM EDT, 10/15 Waxing Crescent ~ 0.58 days
Uranus Pisces +5.7 5.0°N, 8PM EDT, 9/2 Waning Gibbous ~ 16.34 days
Uranus Pisces +5.7 5.0°N, 6AM EDT, 10/27 Waxing Gibbous ~ 11.92 days
Neptune Aquarius +7.9 6.0°N, Noon EDT, 10/24 Waxing Gibbous ~ 9.17 days



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