December 2014 – Skies News

Focus Constellations: Cassiopeia, Perseus, Taurus, Auriga, Camelopardalis, Lynx, Ursa Major, Ursa Minor, Draco, Cepheus, Lyra, Cygnus, Pegasus, Pisces, Andromeda, Aries

Comet Journal

C/2012 K1 (PanSTARRS) is at 6th magnitude but is deep into the southern hemisphere skies where it will remain throughout 2015 as it moves toward the outer Solar System and diminishes in brightness.

The next relatively bright comet is the long period comet, C/2014 Q2 (Lovejoy), discovered on August 17, 2014. The comet is shooting up through the Solar System between the orbits of Earth and Mars. It may appear just above the southern horizon in the constellation Columba in late December and reach naked eye visibility in January. It will pass 0.469 AU (43,600,000 mi) from Earth in Eridanus on January 7th, cross the celestial equator between Eridanus and Taurus on the 9th, and reach perihelion between Perseus and Triangulum on the 30th when it may achieve 6th magnitude. The comet will then dim as it continues up and away through Andromeda and eventually returns to the Oort Belt.

Mars Landers

Between Oct. 14, 2014 (Sol 3812) and Nov. 11, 2014 (Sol 3839) Opportunity drove 792 feet southward in a journey of approximately 1.6 miles to reach Marathon Valley where orbital imagery revealed a likely location for rocks containing abundant clay minerals. If found, they may provide evidence for the nature of the ancient environments in which the rocks formed. In the process, Opportunity departed from Ulysses Crater and traversed an obstacle course through a rugged ejecta field in which two targets (Birmingham and Crimson Tide) were examined and turned out to be rocks solidified from impact melts. During its trip the rover produced incredible images of Comet Siding Springs’ close bypass of Mars. It also experienced 2 more flash memory amnesia events on Sol 3813 (Oct. 15, 2014) and on Sol 3817 (Oct. 19, 2014), neither of which impacted operations. As of Sol 3839 (Nov. 11, 2014), the rover was in good health. Solar energy dropped to as low as 434 watt hours per day during a dust storm in October but rebounded to between 505 and 516 watt hours per day in November. Total odometry on Mars for the rover is 25.56 miles (41.14 kilometers)

The sample collected by Curiosity at Mt. Sharp on Sept. 19th was analyzed by the CheMin instrument and found to contain much more hematite (Fe2O3) than any rock or soil sample previously analyzed by CheMin during the two-year-old mission. The mission landing site was inside Gale Crater, an impact basin about 96 miles (154 kilometers) in diameter with the layered Mount Sharp rising about three miles (five kilometers) high in the center.

Rocks analyzed earlier also contained iron-oxide minerals, mostly magnetite (Fe3O4). The drilled rocks at Yellowknife Bay and on the way to Mount Sharp contain at most about one percent hematite and much higher amounts of magnetite. The Mount Sharp sample has about eight percent hematite and four percent magnetite. Hematite can form from magnetite placed in oxidizing conditions. The oxidation of hematite into magnetite releases energy which can be utilized be microorganisms. Some Earth organisms depend on this as their main source of energy.

The Mount Sharp sample is only partially oxidized, and preservation of magnetite and olivine indicates a gradient of oxidation levels which could have provided a continuing source for chemical energy for microbes.

Meteor Showers

The December meteor showers include the Geminids peaking on the 13th and morning of the 14th and the Ursids peaking on the evening of the 22nd. The former has to contend with the last quarter Moon on the morning of the 14th and the latter occurs near New Moon. The Geminid meteors are derived from a 5 mile diameter asteroid called 3200 Phaethon which passes every 1.5 years and will be within 120,000 miles from Earth in 2017. They produce one of the most reliable showers which may approach a rate of 50 to 100 meteors per hour. The Ursids normally peak at 10 per hour unless their parent, Comet 8P Tuttle, is in the neighborhood such as in 1945 and 1986 when rates exceeded 100 per hour.

Minor showers in December include the Coma Berenicids and the Leo Minorids on the 16th and the 20th which typically range from 1 – 3 meteors per hour, and 4 southern hemisphere showers between December 6th and December 12th which compete with the gibbous Moon.

Winter Solstice

The solstice on December 21st at 6:03PM EST provides the longest night and shortest day of the year. The northern hemisphere is tilted away from the Sun which is above the Tropic of Capricorn (23.5°S) and only 21.5° above the south point on the horizon at solar noon on the 21st for those who live at latitude 45°N.

Since Earth’s northern hemisphere is tilted away from the Sun, our night view in December reveals more of the sky below the plane of our orbit and we see more southern constellations and their plethora of bright, first magnitude stars than can be seen at other times. The bright stars of Orion, Canis Major, Canis Minor, and Taurus sparkle in clear winter skies.

Earth’s tilt causes Winter Solstice Full Moons to be higher above the southern horizon than at any other time of the year. The orbital plane of the Moon is slightly tilted relative to that of Earth. Imagine a person with the Sun at his or her back leaning steeply forward (23.5°) in waist deep water with a Hula Hoop tilted at 5° relative to the water surface. The water surface is the plane of Earth’s orbit, the person’s belt is Earth’s equator, and the Hula Hoop is the Moon’s orbit. The position of Earth’s equator (belt) is displaced to the south (below) of Earth’s orbital plane (water surface) by 23.5° each December. However due to the angle between the Earth’s and Moon’s orbit (Hula Hoop), the Moon is almost 5° south (below) of Earth’s orbital plane (water surface) in December, 2014, and is closer to the southern horizon than in years such as 2006 when the 5° displacement was to the north (above water surface) and December’s Full Moon was 10° farther north.

The two places where the orbits intersect of are known as the syzygies. The Moon’s orbit rotates like a Hula Hoop every 18 years so each syzygy will move 360° in this period and the next high Full Moon will occur in 2024. In December of 2015 (2006 + 9), the Moon is at its maximum distance south and even closer to the horizon.

When the Moon is at a syzygy, the Sun, Earth, and Moon will be precisely lined up causing total eclipses at New and Full Moon phases, so there is an eighteen year cycle of eclipses. If a particular type of solar or lunar eclipse occurs at a given time, a similar eclipse will occur 18 years later. The tables of astronomical events tediously recorded by the Babylonians revealed this cycle allowing them to predict eclipses even though they did not understand why they occurred.

Planet Plotting

December’s evening planets include Mercury, Venus, Mars, Jupiter, Neptune, and Uranus. Mercury and Venus return to the evening sky after the former passes through conjunction with the Sun on December 8th (Venus was in solar conjunction in November). Both will be low the the southwest in Sagittarius after sunset in December. Distant Mars (+1.0 to +1.1) moves through Sagittarius and into Capricornus in the southwestern sky and sets 3 hours after after the Sun in December. On the 12th, it reaches orbital perihelion which is currently on the other side of the Sun. Neptune (+7.9 in Aquarius) and Uranus (+5.8 in Pisces) are visible in the south after sunset and respectively set before and after midnight.

Jupiter and Saturn are the lone planetary denizens of the predawn sky in December. Jupiter (-2.2 to -2.4) rises in Leo at 10PM and sets well after dawn. Saturn (+0.5 to +0.6 in Libra) makes its appearance after the first week of December in the southeastern sky just before dawn after passing through solar conjunction on November 18th.

Planet……Constellation……Magnitude……Planet Passages

Sun…Scorpius, Ophiuchus, Sagittarius…-26.8…..New Moon, ………………………………………………………12/21, 8:36PM EST Mercury..Scorpius, Ophiuchus, Sagittarius..-0.6 to-1.1 ………………………………………………………Superior Conjunction …………………………………………………………12/8, 5AM EST Venus……Sagittarius………..-3.9
Mars……..Capricornus………+1.0 to +1.1
Jupiter…..Leo…………………..-2.2 to -2.4
Saturn…..Libra…………………+0.5to +0.6
Uranus….Pisces………………..+5.8
Neptune…Aquarius…………..+7.9

December Moon

Lunation 1137 began with November’s New Moon on the 22nd at 7:32AM EST and ends 29.11 days later with the New Moon of December on the 21st at 8:36 PM EST.

The Full Moon of December occurs in Ophiuchus on the 6th at 7:27AM EST. It is the “Moon before Yule” or “Long Night Moon.” The latter refers to the fact that the Full Moon is above the horizon for a longer time than any other time of the year due to the high arc that it takes through the sky as the Earth rotates. The Full Moon is highest in the sky in December for northern hemisphere observers and the Sun is lowest because the Earth is tilted away from the Sun and toward the Moon. Colonial Americans called it the “Christmas Moon” and Celts called it the “Cold Moon” and Medieval English referred to it as the “Oak Moon.” Chinese call it the “Bitter Moon” and Anishnaabe (Odawa and Ojibwe) of northern Michigan call it “Manidoo-gizisoons” (Small Spirits Moon).

Apogee distance (maximum distance) is 251,395 miles (63.44 Earth Radii) from Earth on the 12th at 6:03PM EST. The Moon is nearest (perigee) in its orbit (226,675 miles or 57.19 Earth Radii) on December 24th at 11:42AM EST.

Planet..Constellation..Magnitude..Moon Passage..Moon ……………………………………………………………Phase/Age

Sun…Ophiuchus………-26.8………….8:36PM EST, 12/21 ……………………………………………………..New ~ 0 days Mercury..Sagittarius….-0.9……….7.0°N, 11AM EST, 12/22 …………………………………………Waxing Crescent ~ 0.6 days Venus…..Sagittarius….-3.9……….6.1°N, 10PM EST, 12/22 …………………………………………Waxing Crescent ~ 1.06 days
Mars…Capricornus……+1.1……….6.0°N, 3AM EST, 12/25 ………………………………………….Waxing Crescent ~ 3.27 days Jupiter….Leo…………….-2.2……….5.0°S, 11PM EST, 12/11 ………………………………………….Waning Gibbous ~ 19.21 days Saturn…..Libra………….+0.6……….1.5°N, 4PM EST, 12/19 ………………………………………….Waning Crescent ~ 26.92 days Uranus….Pisces…………+5.8………1.2°N, 7PM EST, 12/01 …………………………………………..Waxing Gibbous ~ 9.04 days Uranus….Pisces…………+5.8………1.2°N, Midnight EDT, 12/28 …………………………………………..Waxing Gibbous ~ 6.14 days Neptune..Aquarius……..+7.9………4.0°N, 10AM EST, 12/26 …………………………………………..Waxing Crescent ~ 4.56 days