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October 2016 Skies


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October Skies

by Dick Cookman

10/10/2016

 

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

Focus Constellations: Camelopardalis, Auriga, Perseus, Cassiopeia, Andromeda, Pegasus, Cepheus, Cygnus, Lyra, Aquila, Hercules, Draco, Ursa Minor, Ursa Major, Bootes

Comet Journal

October is not a good month for bright or even moderately bright comets. Nothing is expected to exceed 11th magnitude necessitating giant binoculars or telescopes for comet observation. There are 4 Christmas, winter and Easter comets which may achieve naked eye visibility. They include Comet 45P/Honda-Mrkos-Pajdusakova, Comet 2P Enke (see Taurid meteor shower below), Comet V2 Johnson, and Comet 41P/Tuttle-Giacobini-Kresak.

Mars Landers

Opportunity departed from the northern margin of Marathon Valley on the rim of Endeavour Crater on Sol 4453 (August 2, 2016) and headed south across the valley. The rover reached the southern side of the valley on Sol 4480 (August 30, 2016). After receiving its 10th mission extension on Sept. 1st, the rover entered a small valley (Lewis & Clark Gap) cutting through Wharton Ridge on the southern side of Marathon Valley. Opportunity then descended the ridge into Bitterroot Valley which trends northeastward and drops into the depths of Endeavour Crater. By Sol 4500 (Sept. 20, 2016) the rover reached Spirit Mound at the eastern terminus of Bitterroot Valley. After examining the rocks at a nearby surface feature (Gasconade), scientists plan to make detailed observations of the material making up the mound, then move the rover onto the vast floor of the 14 mile wide crater and compare the rocks of the floor to the sulfate-rich rock of the plains surrounding the crater.

From Sol 4473 (Aug. 23, 2016) through Sol 4514 (Oct. 4, 2016) Opportunity traveled 0.21 miles (0.34 kilometers) achieving a total distance on Mars of 26.99 miles (43.44 kilometers). Solar array energy production ranged from 453 to 582 watt-hours per day.

On Sol 1422 (August 5, 2016), after almost 4 years of travel on Mars, Curiosity arrived at the Murray Buttes region of lower Mt. Sharp, the Mt. Rainier size peak in the center of 96 mile wide Gale Crater. The buttes are an area of isolated exposures of younger sandstone resting above the lower 300 foot thick lake bottom mudstone of the 600 foot thick Murray Formation. Sandstone buttes and mesas are capped with a relatively cohesive rock layer which protects them from erosion. The scenic landscape is very reminiscent of spectacular areas in the American southwest. The sand making up the sandstone accumulated as sand dunes built on the underlying material of the Murray Formation. The sand dunes were later lithified into rock as minerals deposited by groundwater percolating through the sand cemented the sand grains together. Later erosion removed most of the lithified dune layer leaving the isolated remnants.

Since the area appeared to be a likely candidate for the 14th drill site, a location near the base of one of the buttes was chosen for drilling. After an aborted drilling attempt at Quela on Sol 1461 (Sept. 15, 2016), the drilling problem was assessed and a second attempt on Sol 1466 (Sept. 19, 2016) recovered an appropriate sample of drilling powder. Curiosity resumed its uphill trek away from Murray Buttes and toward the younger rock above the Murray Formation. Detailed measurements made of the sandstone of the Murray Formation at the Kopong outcrop on Sol 1473 (Sept. 27, 2013) revealed details in the cross-bedded layering, rock texture, and abundant light colored mineral veins lacing through the rock layers which were formed as calcite crystals were precipitated from ground water percolating through the fractured bedrock.

Analysis of gases measured by the regular atmospheric sampling conducted by Curiosity reveals that the ratios of isotopes of xenon and krypton indicate unexpected abundances of certain isotopes. This can be explained by cosmic ray bombardment of barium and bromine on the Martian surface altering them to xenon and krypton which then escaped to the atmosphere.

As part of the two year mission extension commencing on Oct. 1st, the next year will be devoted to examination of the upper part of the Murray Formation and the following year will concentrate on the overlying Hematite Unit (a ridge which is 1.5 miles away and is capped with material rich in hematite) and the more distant Clay Unit. Both were initially identified from orbit by the Compact Imaging Spectrometer on board the Reconnaissance Orbiter. Due to their compositions, these younger units are likely to have formed in wet environments and may yield additional data about the moist environments on ancient Mars which could have provided conditions favorable for microbial life.

Meteor Showers

October Meteor Showers include the Camelopardalids (10/5), the Draconids (10/8), the Taurids (10/10), the Delta Aurigids (10/11), the Epsilon Geminids (10/18), the Orionids (10/21), and the Leo Minorids (10/24). All but 3 are minor showers. The Draconids consist of debris shed from from Comet 21P/Giacobini-Zinner during previous passages. They are extremely variable ranging from 10 to 60 meteors per hour and occasionally storming to 100's to 1000's per hour. The Taurids (~5 per hour) are from Comet 2P Enke and the Orionids (~20 to 70 meteors per hour in dark skies) are the remnants of Comet Halley.

Halloween

As with most of our holidays, the origin of Halloween is related to an astronomical event. It is the eve of All Saints Day on Nov. 1st, a cross-quarter day, half way between the Autumnal Equinox and the Winter Solstice. Some cultures recognized transitions between seasons on the cross-quarter days half way between the equinoxes and solstices (the "quarter" days). The quarter days were considered to be the middle of each season. The cross-quarter days include Candlemas (Groundhog Day), Beltane (May Day), Lamas, and All Saints Day (Hallowmas or Hallow’s mass). Hallow’s can refer to saints, the relics of saints, or the shrines in which the relics are kept. Hallowmas was established to replace an ancient Celtic festival marking the end of summer when the dead were believed to arise for one night. People would commemorate the event by dressing up and acting like the undead.

Planet Plotting

Venus (-3.9 to -4.0) is visible in the southwestern sky after sunset in October. During the month, it will move from Libra, through Scorpius, and into Ophiuchus and will be about 3.0° south of Saturn at 4AM EDT on the 30th.

Saturn (+0.5 to +0.6) and Mars (+0.1 to +0.3) spend October in the southwestern sky in Ophiuchus and Sagittarius respectively. In early October they set before 10PM EDT and by the end of the month they set about 8PM EDT. Neptune (+7.8) in Aquarius and Uranus (+5.8) in Pisces rise before sunset and set in the wee hours after midnight. Uranus is at its brightest of the year on the 15th at 1PM EDT when it is at opposition.

Jupiter (-1.7) in Virgo moved into the morning sky after its conjunction with the Sun on Sept. 26th. It rises slightly after 7AM EDT in early October and after 5:30AM EDT by the end of the month. Mercury (-0.9 to -1.4) rises in Leo at about 5:30AM EDT at the beginning of the month and will be found less than a degree NNE of Jupiter on the morning of the 11th. It grows brighter as it moves through Virgo and rises with the Sun after 7AM EDT at month's end. After Superior Solar Conjunction at noon on the 30th, Mercury will move into evening skies.

PlanetConstellationMagnitudePlanet Passages
SunVirgo-26.8New Moon, 10/30, 1:38AM EDT
MercuryLeo,Virgo-0.9 to -0.1.4Superior Conjunction, 10/27, Noon EDT
Jupiter, 0.9°S 10/10, Midnight EDT
VenusLibra, Scorpius, Ophiuchus-3.9 to 4.0Saturn, 3.0°N 10/30, 4AM EDT
MarsSagittarius+0.1 to +0.3 
JupiterVirgo-1.7Mercury, 0.9°N 10/10, Midnight EDT
SaturnOphiuchus+0.5 to +0.6Saturn, 3.0°S 10/30, 4AM EDT
UranusPisces+5.7 
NeptuneAquarius+7.8 to +7.9 

October Moon

The New Moon of October is on the 30th at 1:38AM EDT. The New Moon is the beginning of Lunation 1161 which ends 29.86 days later with the New Moon of November 29th at 7:18AM EST.

The Full Moon in October in Pisces occurs at 12:23AM EDT on the 16th. It is normally called the "Hunters Moon". It was also the "Hunters Moon" for the Celts and Chinese mark the October Moon as the “Kindly Moon". To Medieval English, it was the “Blood Moon” and the Anishinaabe (Odawa and Ojibwe) people of northern Michigan celebrate it as “Binaakwe-giizis” (Falling Leaves Moon).

It was also called the "Hunters Moon" in Colonial America. After the Harvest Moon in the previous month when the fields were reaped, hunters moved into the fields seeking game feeding on the crop remants and hiding in the stubble. The products of the hunt resupplied their larders in preparation for the oncoming winter.

The Moon is at the apogee position in orbit (maximum orbital distance) at 252,336 miles (63.67 Earth radii) from Earth on the 4th at 7:03AM EDT. It is again at aphelion at 252,688 miles (63.76 Earth radii) from Earth on the 31st at 3:29PM EDT. Perigee distance (closest to Earth) is 222,364 miles or 56.11 Earth radii on the 16th at 7:34PM EDT. Since Full Moon occurs when the Moon is closer to Earth than usual, the Full Moon appears as a large "Supermoon". The Full Moon lineup of the Sun, Earth, and a nearby Moon will force seaside residents to be on the alert for unusually high tides which will also result in higher than normal "tidal bore waves" moving farther upstream in rivers draining into the sea.

PlanetConstellationMagnitudeMoon PassageMoon Phase/Age
SunVirgo-26.81:38AM EDT, 10/30New ~ 0 days
MercuryVirgo-1.44.2°NNE,1PM EDT, 10/30Waxing Crescent ~ 0.18 days
VenusVirgo-3.95.0°N, 1PM EDT, 10/3Waxing Crescent ~ 3.33 days
MarsSagittarius+0.17.0°N, 8AM EDT, 10/8Waxing Crescent ~ 8.12 days
JupiterVirgo-1.70.4°N, 6AM EDT, 10/28Waning Crescent ~ 28.04 days
SaturnOphiuchus+0.54.0°N, 4AM EDT, 10/6Waxing Crescent ~ 5.96 days
UranusPisces+5.73.0°S, 10PM EDT, 10/15Waxing Gibbous ~ 15.71 days
NeptuneAquarius+7.81.2°N, 2AM EDT, 10/13Waxing Gibbous ~ 12.87 days


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