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October Skies


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October Skies

by Dick Cookman

10/2/2013

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

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

Comet Journal

Three comets grace the skies of October. None are yet visible to the naked eye and the first one below will remain beyond the edge of most observers' vision at magnitude 7. The last two below will become visible to the eye in November.

Comet 2P (Enke) will visit the circumpolar constellations after midnight as it appears to track eastward between Ursa Major and Leo at 7th magnitude. It treks around the Sun every 3.3 years and is closest to the Sun in mid-November. It passes Earth on October 17, 2013 (at a distance of 44.7 million miles or 0.48 AU.) Every 10 circuits it makes an unusually close approach to Earth and the last was in July, 1997 at a distance of 0.19 AU.

Prospective super Comet C/2012 Ss1 (ISON) may rival the bright planets in November. It may reach naked eye viewing levels in October, but, if not, will still be a fine sight in binoculars at 7 - 8th magnitude appearing to move eastward through the head of Leo which rises in the northeast after midnight. It is within 7 million miles of Mars on the 1st.

Comet C/2013 R1 (Lovejoy) is another 8th magnitude late night apparition appearing to move eastward through Monoceras and into Canis Minor after midnight in October.

Mars Landers

Like a kid in a candy store, Opportunity skirted Solander Point in September, hopping around over a span of 500 feet seeking contacts between different geologic formations by checking out the rock outcrops and individual rocks in the large boulder field on the point. Field geologists on Earth will often identify underlying rock units by the pebbles, cobbles, and boulders (called float) at the surface of the ground.

Targets examined included a cliff face called Coal Island, a dune field, and a half dozen rock targets. Mission scientists utilized all of the rover's instruments in their investigations including the rock Abrasion tool, the Microscopic Imager, the Panoramic and Navigation Cameras, and the Alpha Particle X-ray Spectrometer. Solar array output averaged around 340 watt-hours from Sol 3410 (August 27) to Sol 3437 (September 24).

On September 5th, Curiosity reached the first of five selected waypoints which dot the roving science laboratory?s 13 month southwestward route to Mount Sharp from the Glenelg area investigated during the first half of 2013. Waypoint 1 is at the outer boundary of the lower layers of Mount Sharp. The waypoint is about one-fifth of the way along the approximately 5.3-mile (8.6-kilometer) route which was plotted by examining images from Earth based and Mars orbiter observations.

As it approached the waypoint the rover crested a rise called Panorama Point and imaged the 245 foot distant pale toned rock outcrop which was picked out earlier from Mars Reconnaissance Orbiter images. The first part of the trip to the rise was directed by mission scientists from earlier images and most of the last 218 feet was accomplished by autonomous navigation by Curiosity through an area not visible in pre-existing images. The trip was supervised by the on board Hazard Avoidance System which was was enabled for the first time on Mars for this mission allowing the rover to traverse the uncharted area by itself.

Analysis of observations and measurements by the rover's science instruments during the first four months after the August 2012 landing are detailed in five reports in the Sept. 27 edition of the journal Science. The mission at the Gleneld area uncovered evidence for ancient environments conducive for microbial life in analyses of the rock powder drilled from two rock outcrops in Yellowknife Bay. The rock layers contained elements typically produced in sediments deposited from low salinity, neutral pH water. In addition to the water chemically incorporated into the molecular structure of the minerals making up the rock, water molecules bound to fine grained particles accounts for 2% of the mass of the particles. Since the fine particles are similar to the dust distributed over the entire planet, the 2% water content is probably a planet wide phenomena. The igneous rock (Jake M) found between the landing site and Glenelg was unlike Martian rock previously examined and similar to rocks found in oceanic rift zones on Earth where lava derived from magma formed in the upper mantle is ejected beneath the sea. This combination of sedimentary and igneous rock evidence reveals a time period during which Mars had some form of plate tectonics and large, low salinity, neutral pH water bodies.

Researchers theorized that the rock layers comprising Mt. Sharp may include a much broader snapshot of the geologic history of Mars and the layers the rover traverses on the trip include a segment of that history. Mission scientists developed the sequence of waypoints in hopes of investigating this multiplicity of stages in the evolution of the planet.

Meteor Showers

Meteor Showers in October include Draconids on the 8th, Southern Taurids on the 10th, and Orionids on the 21st. The latter normally outperforms its compatriots but will be challenged by a bright waning gibbous Moon this year. As a result the Southern Taurids will probably be our best shower at about 5 meteors per hour unless the Draconids produce a rare storm of meteors like the rates of 1000's per hour viewed in 1933 and 1946. The Orionids and Draconids are respectively composed of debris from Comet Halley and Comet 21P/Giacobini-Zinner. The Southern Taurids may be from Comet Enke.

Galactic Neighborhood

Although two thirds of the U.S. population suffers from light pollution which eliminates viewing of the Milky Way, viewers with dark, unpolluted night skies still are favored with naked eye viewing of our near neighbors, the Andromeda Galaxy in the northern hemisphere and the Magellanic Clouds in the southern hemisphere. Views of other members of the Local Group of Galaxies require binoculars and telescopes which allow us to peer toward the center of the Local Group in October. During Autumn the inclination of the Earth provides nightime views beyond the the southern hemisphere of the Milky Way for observers in the northern hemisphere.

In the Spring the views are beyond the northern hemisphere of our galaxy toward the center of the gigantic supercluster (cluster of clusters) of galaxies beyond Virgo. Members of our Local Group lie within a few million light years of Earth and members of our local supercluster lie within a few hundred million light years.

Planet Plotting

Evening planets Mercury, Venus, and Saturn are low on the west-southwest horizon after sunset in October. Mercury and Saturn are about half way between the setting Sun and Venus. The morning planets are Jupiter and Mars with Jupiter rising in the latter part of evening and Mars rising in the wee hours after midnight. Neptune (+7.9 in Aquarius) sets as Mars rises and Uranus (+5.7 in Pisces) sets well before dawn. Uranus reaches opposition and maximum brightness on the 3rd.

Mercury is in Virgo and reaches maximum eastern elongation from the Sun on the 9th. However, it will be very low in the southwest and hard to find in the glow of sunset even though its magnitude is -0.1. Venus glows brightly in the southwestern sky and can be viewed after sunset all month long as it paces the Sun as each move eastward through the sky. It will brighten and reach a maximum in early December. Venus moves through Libra and Scorpius and will pass within 2° of red supergiant Antares on the 16th.

Jupiter is by far the brightest planet after Venus sets. It will increase in brilliance by another 50% by the end of the year. Mars is in Leo and is also getting brighter as opposition in early 2014 approaches.

PlanetConstellationMagnitudePlanet Passages
SunVirgo-26.8New Moon, 10/4, 8:35PM EDT
MercuryVirgo, Libra-0.1 to +4.8Saturn, 5°N, 10/10, 3PM EDT
Max Eastern Elongation 10/9, 6AM EDT
VenusLibra, Scorpius, Ophiuchus-4.2 to -4.5 
MarsLeo+1.6 to +1.5 
JupiterGemini-2.2 to -2.4 
SaturnLibra+0.7 to +0.5Mercury, 5°S, 10/10, 3PM EDT
UranusPisces+5.7Opposition, 10/3, 10AM EDT
NeptuneAquarius+7.9 

October Moon

October's New Moon on the 4th at 8:35PM EDT marks the start of Lunation 1123 which is 29.47 days long and ends with November's New Moon on the 3rd.

The Full Moon in Pisces on October 18th at 7:38PM EDT is the Harvest Moon this year. Colonial Americans called the Full Moon of September the "Harvest Moon" and that of October the "Hunter's Moon". "Harvest Moon" has since been defined as the full moon following the Autumnal Equinox. Some observed it in September because they define it as the full moon closest to the Equinox. Celts referred to the October Moon as the as the "Harvest Moon" and the Chinese call it the "Kindly" Moon. Medieval English named it the "Blood Moon". The Anishnaabe (Chippewa and Ojibwe) of northern Michigan call it "Binaakwe-giizis" (Falling Leaves Moon).

The Moon is closest to Earth at perigee on the 10th at 7:14PM EDT. It will be 229,792 miles away or 57.98 Earth Radii. At apogee on the 25th at 10:24AM EDT, the Moon will be 251,380 miles away or at a distance of 63.43 Earth radii.

PlanetConstellationMagnitudeMoon PassageMoon Phase/Age
SunVirgo-26.88:35PM EDT, 10/4New ~ 0 days
MercuryVirgo-0.13.0°N, 6PM EDT, 10/6Waxing Crescent ~ 1.70 days
VenusLibra-4.35.0°N, 8AM EDT, 10/8Waxing Crescent ~ 2.57 days
MarsLeo+1.67.0°S, 2AM EDT, 10/1Waning Crescent ~ 25.11 days
MarsLeo+1.56.0°S, 9PM EDT, 10/29Waning Crescent ~ 25.14 days
JupiterGemini-2.45.0°S, 6PM EDT, 10/25Waning Gibbous ~ 22.07 days
SaturnLibra+0.71.9°S, Midnight EDT, 10/6Waxing Crescent ~ 3.41 days
UranusPisces+5.73.0°N, 5PM EDT, 10/17Waxing Gibbous ~ 14.32 days
NeptuneAquarius+7.96.0°N, 2AM EDT, 10/15Waxing Gibbous ~ 11.66 days




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