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by Dick Cookman
Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, August Moon
Focus Constellations: Cassiopeia, Perseus, Camelopardalis, Ursa Major, Ursa Minor, Draco, Cepheus, Cygnus, Lyra, Hercules, Corona Borealis, Bootes, Ophiuchus, Aquila, Pegausu, Andromeda
The brightest comet of August is Comet C/2014 E2 (Jacques) at 6th magnitude in the predawn skies. It will move along the north side of the Milky Way from Auriga to Cepheus by the end of the month. After discovery in March, it passed through perihelion on July 3rd and swooped by Venus on the 13th. It will be closest to Earth when it crosses our orbit on August 28th (52,000,000 mi) after which it continues outward to the Oort belt on its 22,000 year journey around the Sun. Best viewing will be in the latter half August when it will be near the zenith in the predawn skies.
C/2012 K1 (PanSTARRS) is next brightest at 7th magnitude. It is descending into the plane of the solar system as it moves southward from Cancer into Hydra in August. It will reach perihelion on August 27th and achieve maximum brightness of 6th magnitude in autumn southern hemisphere skies as it continues on the outward trip below the Earth in September.
C/2013 V5 (Oukaimeden) was discovered in November, 2013 and rapidly increased brightness from 19th magnitude to 10th magnitude by July. It is expected to reach 7th magnitude in August. It is moving along the Milky Way between Orion and Gemini and will be in Canis Minor by the end of the month. It will be easily viewed in binoculars and will pass closest to Earth (less than 45 million mi.) on Sept. 16th. At perihelion in late September the comet may approach 5th magnitude.
Comet C/2012 X1 (LINEAR) is at 9th magnitude. LINEAR is currently in southern hemisphere skies and will reappear above the southern horizon in Sculptor next year as it drops away from Earth on its journey back to the Oort Belt.
After completing investigation of the aluminum-hydroxyl clay mineral area on the west rim of Endeavour Crater, Opportunity proceeded southward on the west rim of the crater toward a feature called Broken Hills on Sol 3711 (July 2, 2014). The rover's journey in July was targeted on another clay rich mineral area called Marathon Valley which was spotted from orbit. Between Sol 3710 (July 1, 2014) and Sol 3738 (July 30, 2014), the rover managed to travel 0.41 miles (660 meters) of the 1.2 mile journey to the valley.
On the way, Opportunity collected numerous Panoramic Camera (Pancam) images, Navigation Camera (Navcam) panoramas, InSIGHT atmospheric opacity measurements, Microscopic Imager (MI) mosaics and Alpha Particle X-ray Spectrometer (APXS) readings of the surface targets Rosebud Canyon and Trebia, and atmospheric argon measurements with the APXS.
Flash memory amnesia events occurred on Sol 3724 (July 15, 2014) and Sol 3727 (July 19, 2014). However, the science data were recovered with subsequent second readouts. Solar array energy production during July was excellent, ranging between 650 and 775 watt-hours per sol.
According to NASA's JPL website, Curiosity landed inside Gale Crater on Aug. 5, 2012, PDT (Aug. 6, 2012, EDT). During its first year of operations, it fulfilled the major science goal of determining whether Mars ever offered environmental conditions favorable for microbial life. The mission made important discoveries by finding evidence of ancient lake and river environments. Clay-bearing sedimentary rocks on the crater floor in an area called Yellowknife Bay yielded evidence of a lakebed environment billions of years ago that offered fresh water, all of the key elemental ingredients for life, and a chemical source of energy for microbes, if any existed there.
In early May, NASA’s Curiosity Mars rover approached a sandstone slab in the middle unit of a rock layer (called Winjana) which surrounds the base of a small 16 foot tall butte called Mount Remarkable at “the Kimberley.” The coarser grains in the sandstone slab and the more abundant magnetite compared to the previous lakebed samples analyzed are indicative of a more active depositional environment such as river or wave environments which would remove clays and preferentially deposit coarser sand grains and denser magnetite grains.
As it approaches the second anniversary of its landing on Mars, NASA’s Curiosity rover is also approaching its first close look at bedrock that is part of Mount Sharp, the layered mountain in the middle of Mars’ Gale Crater. During its second year, it has been driving toward long-term science destinations on lower slopes of Mount Sharp. Those destinations are in an area beginning about 2 miles (3 kilometers) southwest of the rover’s current location, but an appetizer outcrop of a base layer of the mountain lies much closer -- less than one-third of a mile (500 meters) from Curiosity. The rover team is calling the outcrop Pahrump Hills.
“We’re coming to our first taste of a geological unit that’s part of the base of the mountain rather than the floor of the crater,” said Curiosity Project Scientist John Grotzinger of the California Institute of Technology, Pasadena. “We will cross a major terrain boundary.”
The Perseid Meteor Shower on the 12th will have to compete with the glare of the almost full waning gibbous Moon in Capricornus. Best viewing will be when Perseus is slightly east of the zenith before and after 5AM on the 13th as the Moon sets about an hour or so before sunrise. Expect 1 or 2 meteors/minute in dark skies. The Earth orbits through the residual river of debris from previous passages of Comet 109P Swift-Tuttle from July 17th to Aug. 24th and drives through the densest debris in the center of the river on the night of the 12th and 13th.
The Perseids provide more bright fireballs the any other shower. Great Balls of Fire by Jerry Lee Lewis is an apt descriptions of these fireballs which result from large meteoroids broken off of the huge 16 mile wide comet nucleus by solar heated gases, vaporized ices, and dust blasted from the comet.
Mars and Saturn are evening planets in August. Mars (+0.4 to +0.6) in Virgo sets before midnight in early August. Saturn (+0.5 to +0.6) in Libra sets about midnight on the 1st and both set 2 hours earlier at the end of the month. Mars catches up with Saturn as they orbit the Sun in August and passes the ringed planet on the 27th when they are within 4° of one another at 9AM EDT.
Jupiter (-1.8) in Cancer was in conjunction with the Sun on July 24th. It is within 0.2° of Venus at midnight on the 17th when both rise slightly before the Sun. In late August it will rise 2 to 3 hours before sunrise. Mercury, Venus, Uranus, and Neptune are the other morning planets. Venus in Cancer and Leo is visible in the east before dawn all month long at magnitudes (-3.8 to -3.9). Mercury disappears from the evening sky in early August, reaches Superior Conjunction on the 8th and reappears in the predawn skies at month's end. Neptune (+7.8) in Aquarius and Uranus (+5.8) in Pisces are in the southwestern predawn skies.
|Sun||Cancer, Leo||-26.8||New Moon, 8/25, 10:13AM EDT|
|Mercury||Cancer, Leo, Virgo||-1.5/-0.3||Superior Conjunction 8/8, Noon EDT|
|Venus||Cancer, Leo||-3.8/-3.9||Jupiter, 0.2°S, 8/17, Midnight EDT|
|Mars||Virgo||0.4 to +0.6||Saturn, 4.0°N, 8/27, 9:00AM EDT|
|Jupiter||Cancer||-1.8||Venus, 0.2°N, 8/17, Midnight EDT|
|Saturn||Libra||+0.5 to +0.6||Saturn, 4.0°S, 8/27, 9:00AM EDT|
|Neptune||Aquarius||+7.8||Solar Opposition, 8/29, 11:00AM EDT|
Lunation 1133 began on the New Moon of July 26th and ends 28.65 days later when the New Moon of Aug 25th occurs at 10:13AM EDT.
The Full Moon of August is in Capricornus on the 10th at 2:09PM EDT. The August Moon was traditionally named the "Dog Days Moon" in Colonial America because Sirius in Canis Major rises with the Sun in early August. Ancient Egyptians observed that this coincided with the timing of the yearly Nile floods which provided critical nutrients for their flood plain farm fields and enabled them to establish the first Sun based annual calendar.
For Celts the August Full Moon was the “Dispute Moon.” Chinese call it the “Harvest Moon." To Medieval English it was the “Corn Moon.” Anishnaabe people (Odawa and Ojibwe) of northern Michigan call it “Miini-giizis” (Berry Moon).
The Moon is at the nearest point (perigee) in its orbit (221,765 miles or 55.96 Earth Radii in August) on the 10th at 1:43PM EDT. The highest tides of the month (Spring Tides) occur during New and Full Moon. Since the Full Moon coincides with perigee the closer Moon appears larger (Supermoon) and exerts more gravitational force on the Earth so expect high tides to be higher than normal.
Apogee distance (maximum distance) is 252,602 miles (63.74 Earth Radii) from Earth on the 24th at 2:09AM EDT. This apogee is the most distant of the year so the Spring Tide due to New Moon (32 hours earlier) will be lower than normal.
|Planet||Constellation||Magnitude||Moon Passage||Moon Phase/Age|
|Sun||Leo||-26.8||10:13AM EDT, 8/25||New ~ 0 days|
|Mercury||Leo||-0.4||3.0°S, 2AM EDT, 8/27||Waxing Crescent ~ 1.66 days|
|Venus||Leo||-3.9||6.0°S, 2AM EDT, 8/24||Waning Crescent ~ 27.30 days|
|Mars||Virgo||+0.4||2.0°N, 6AM EDT, 8/1||Waxing Crescent ~ 4.47 days|
|Mars||Libra||+0.6||4.0°N, 8PM EDT, 8/31||Waxing Crescent ~ 6.41 days|
|Jupiter||Cancer||-1.8||5.0°S, 1PM EDT, 8/23||Waning Crescent ~ 26.76 days|
|Saturn||Libra||+0.5||0.7°S, 7AM EDT, 8/4||Waxing Gibbous ~ 8:12 days|
|Saturn||Libra||+0.6||0.4°S, 3PM EDT, 8/31||Waxing Crescent ~ 6.20 days|
|Uranus||Pisces||+5.8||1.2°N, 1PM EDT, 8/14||Waning Gibbous ~ 17.76 days|
|Neptune||Aquarius||+7.8||5.0°N, 10PM EDT, 8/11||Waning Gibbous ~ 15.54 days|