September 2015 – Skies News

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

Comet Journal

Comets in September and October are few, dim, and far between. There are no northern hemisphere comets brighter than 10th magnitude. We will have to wait until early November when C/2013 US10 (Catalina) may burst into predawn skies between Libra and Virgo at magnitude 4 and be visible to the naked eye. It is now at 6th magnitude but is still buried deeply in southern hemisphere skies. It will peak in the latter part of November and remain bright in December and January.

Comet C/2014 Q2 (Lovejoy), currently at 10th magnitude, is between northern Bootes and Hercules in September. It’s orbit is almost perpendicular to Earth’s and the comet is rapidly receding northward in space toward the Oort Belt.

Mars Landers

The currently inoperative status of Opportunity’s flash memory system requires that any data collected and placed in ram memory storage on a given day must be transmitted that day. This requires the rover to remain awake until the Ultra-High Frequency (UHF) relay passes above on each sol. With Mars Odyssey now in a later orbit, relay passes come much later in the day. With winter coming and less sunlight for energy production, these late relay passes cause the rover to consume more energy from the batteries. Other than the flash, Opportunity is in good health and is still capable of science activities and data collection but is restricted to the conditions described above.

On Sol 4081 (July 17, 2015), the rover drove 96.7 feet (29.47 meters) to the northeast to enter Marathon Valley and collected spectacular imagery on the western rim of Endeavour Crater near Spirit of St. Louis Crater. The mission in Marathon Valley is to search for the phyllosilicate clay minerals which were discovered via satellite spectral studies.

On Sols 4095 and 4097 (Aug. 1 and Aug. 3, 2015) the rover had limited science activities and shorter relay passes to save energy for a drive on Sol 4096 (Aug. 2, 2015). The drive was successfully completed, moving the rover over 65.6 feet (20 meters) towards an exposed rock outcrop in a new geologic unit within the valley.

On Sol 4100 (August 6, 2015) the robotic arm was used to conduct contact science on a surface target. The Microscopic Imager (MI) collected a mosaic and then the Alpha Particle X-ray Spectrometer (APXS) was placed for a multi-hour integration. Navcam panoramas are also being collected from this site. Additional investigations in the area continued for the next two weeks including grinding of surface targets to expose fresh surfaces. On Sol 4114 (Aug. 20, 2015), Opportunity ground about 2.5 millimeters into the surface of a target called “Pvt. Robert Frazer” using the Rock Abrasion Tool (RAT) on the end of the robotic arm

Opportunity has now traversed 26.41 miles (42.51 kilometers) over the Martian surface. Solar energy in the last month ranged from 400 to 435 watt hours per day.

Curiosity ascended another 433 feet up Mt. Sharp in Gale Crater in August. On July 30th, the rover drilled at a site called “Buckskin” near the contact zone below the younger Washboard Unit which overlies the older Murray Formation, the basal formation at Mt. Sharp. Light colored mudstones of the Murray Formation underlie finely bedded dark sandstones of the Stimson Unit (base of the Washboard Unit) in Marias Pass.

The target is a high silica area called Lamoose. These rocks are unlike any others found so far on Mars. Silicate minerals on Earth are composed of silicon, oxygen, and other elements. They make up Earth’s crust and mantle. Quartz is a silicate mineral composed of pure silicon and oxygen and is found primarily in the continental crust and its erosional products. Abundant silica poor basalt and absence of quartz in previously examined Martian rocks is more representative of basaltic ocean crust on Earth making the quartz rich rocks quite surprising. The drilling revealed the additional presence of hydrogen indicating that there is water or hydroxyl chemically bonded to the silica minerals.

Meteor Showers

The Aurigid and Epsilon Perseid Meteor Showers occur on September 1st and 9th respectively and are both minor showers averaging up to 5 meteors per hour in dark skies, although the 2008 Epsilon Perseids produced 5 times as many. The Aurigids are lost in the glow of the waning gibbous Moon while the Perseids receive very little competition with the waning crescent Moon. The Aurigids are composed of debris from Comet C/1911 N1 (Kiess) and the origin of the Epsilon Perseids has not yet been determined.

Autumnal Equinox

The Autumnal Equinox occurs on September 23rd at 4:21AM EDT in 2015. Earth’s axis will lean toward the direction of travel in our orbit, positioning it so that it is perpendicular to a line connecting Earth and the Sun. In this orientation, all places on Earth have almost 12 hours of sunlight and 12 hours of darkness (equi – nox, Nox was the Roman Goddess of the Night).

The slight inequality of night and day is not because Nox was a rather unpredictable Goddess, rather it is due to the timing of sunrise and sunset which is influenced by latitude, the period of time required for the entire Sun to appear or disappear, and atmospheric light refraction. The latter two generally delay sunset and cause earlier sunrises, lengthening daytime hours. Lower latitudes experience the equinox later than high latitudes, the fall equinox is delayed until October in equatorial regions.

At the equator the Sun is at the zenith (90° above the south point on the horizon) at solar noon, at 45° North latitude it is 45° above the south point, and at the north pole it is on the horizon (solar altitude above south = 90° – observers latitude).

Planet Plotting

Saturn (+0.5 to +0.6) in Libra is an evening planet throughout September. It is well above the southwestern horizon after sunset and does not set until almost 11PM EDT on Sept. 1st and 9PM on the 30th. Right after sunset at the beginning of the month Mercury (+0.1) is 3 degrees above the western horizon in Virgo. It tracks northward along the horizon during the first half of the month and will get quite difficult to distinguish in the glow of sunset. Neptune (+7.8) in Aquarius rises before sunset followed by Uranus (+5.8) in Pisces two hours later. Both are visible most of the night.

Jupiter (-1.7) was in conjunction with the Sun on August 26th and will reappear in the eastern predawn sky below Leo in early September. A much brighter Venus (-4.5) and a dimmer Mars (+1.8) in Cancer will be be above Jupiter and will close in on the giant planet during September and early October.

Planet……Constellation……Magnitude……Planet Passages

Sun……….Leo, Virgo……….-26.8………………….New Moon, ………………………………………………………..9/13, 2:41AM EDT Mercury…..Virgo…………+0.1 to +1.5…….Inferior Conjunction ………………………………………………………..9/30,11:00AM EDT Venus……Cancer, Leo….-4.5 to -4.8
Mars……..Cancer, Leo……..+1.8
Jupiter…..Leo…………………-1.7
Saturn…..Libra………….+0.5 to +0.6 Uranus….Pisces……………..+5.8
Neptune..Aquarius…………+7.8

September Moon

Lunation 1147 begins with the New Moon of September 13th at 2:41AM EDT which coincides with a partial solar eclipse. It ends 29.68 days later with the New Moon of October 12th at 8:06PM EDT. The partial solar eclipse occurs in southern Africa, the southern Indian Ocean, and Antarctica.

The Full (Supermoon) Moon for September in Aquarius at 10:50 PM EDT on the 27th coincides with a total Lunar Eclipse. Observers in eastern United States can view it in its entirety, from the first appearance of the penumbra (dim Moon) at 8:40PM EDT to the start of the partial eclipse at 9:07PM, then the total eclipse beginning at 10:11PM and ending at 11:23PM.

This Full Moon is the “Harvest Moon” because it is the closest Full Moon to the Autumnal Equinox. The Full Moon is the 10th Moon of the year due to two Full Moons in July and is designated by the Anishinaabe (Odawa and Ojibwe) of the northern Great Lakes as “Binaakwe-giizis” (Falling Leaves Moon). Celts called the September Full Moon the “Singing Moon” and Medieval English referred to it as the “Barley Moon.” It is the “Chrysanthemum Moon” for the Chinese and celebrates the most “romantic” day of the year. Colonial Americans called it the “Harvest Moon” because its light allowed farmers to harvest crops.

At this time of year the path of the Moon, like that of the Sun, makes it’s smallest angle to the horizon. This causes the evening to evening progression of moonrise to be limited to a minimum of 20 minutes in the northern United States as opposed to the average of 50 minutes.

Apogee distance (maximum orbital distance) is 252,565 miles (63.73 Earth radii) from Earth on the 14th at 7:27AM EDT. The “Supermoon” designation is due to the Moon’s proximity slightly more than 12 hours before Full Moon when it is at its closest approach to Earth (perigee) for 2015 of 221,753 miles or 55.95 Earth radii on September 27th at 9:46AM EDT.

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

Sun………..Leo……..-26.8……………………2:41AM EDT, 9/13 ………………………………………………………………New ~ 0 days Mercury…Virgo…….+0.8…………..5.0°N, 2AM EDT, 9/15 …………………………………………Waxing Crescent ~ 1.97 days Venus…..Cancer…..-4.7…………..3.0°N, 2AM EDT, 9/10 …………………………………………Waning Crescent ~ 27.36 days Mars……..Leo……….+1.8…………5.0°S, 7PM EDT, 9/10 …………………………………………Waning Crescent ~ 26.65 days Jupiter……Leo………-1.7…………3.0°SSW, Midnight EDT, 9/12 …………………………………………Waning Crescent ~ 28.57 days Saturn….Libra………+0.6………….3.0°N, 11PM EDT, 9/18 …………………………………………Waxing Crescent ~ 5.85 days Uranus….Pisces…….+5.8………….1.1°S, Noon EDT, 9/1 …………………………………………Waning Gibbous ~ 18.07 days Uranus….Pisces…….+5.8………….1.0°N, 9PM EDT, 9/28 …………………………………………Waning Gibbous ~ 15.75 days
Neptune..Aquarius…+7.8…………3.0°N, 6AM EDT, 9/26 …………………………………………Waxing Gibbous ~ 13.14 days