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July Skies


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July Skies

by Dick Cookman

07/9/2014

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

Focus Constellations: Cassiopeia, Camelopardalis, Lynx, Ursa Major, Ursa Minor, Cepheus, Draco, Cygnus, Lyra, Hercules, Corona Borealis, Bootes, Virgo, Ophiuchus, Aquila

Comet Journal

July skies glisten with 4 comets brighter than 10th magnitude.

The brightest is Comet C/2014 E2 (Jacques) at 6th magnitude in the predawn skies in Taurus on July 2nd when it is at maximum brightness. It will move into and through Auriga as it circuits along the southern edge of the Milky Way during July and rises above the plane of the Solar System. It will pass about 8,000,000 miles from Venus on July 13th and will still be almost magnitude 6 when closest to Earth on August 28th (52,000,000 mi).

Comet C/2013 UQ4 (Catalina) is next brightest at 7th magnitude. It is rapidly moving northward in eastern Andromeda and will shoot by Lacerta, pass Cepheus, and move through Draco as it approaches and skirts Bootes in July. The comet passes perihelion on July 5th and will pass within 30 million miles above Earth when in Cepheus on July 10th. It rises in the late evening and is best viewed in early morning skies well before dawn. Initially defined as an asteroid when discovered on Oct. 23, 2013, it was determined to be a long period "Dark Comet" which is now departing from the inner solar system on a 500 year counter clockwise orbit originating in the Oort or Kuiper Belt. Dark Comets appear asteroid-like because a deficiency of lighter elements and dust that were blown away during previous approaches to the Sun.

Comets C/2012 K1 (PanSTARRS) and C/2012 X1 (LINEAR) are at 8th and 9th magnitude respectively. PanSTARRS is descending into the plane of the solar system as it moves southward between Leo and Cancer in July. It may reach 6th magnitude in autumn southern hemisphere skies. It will reach perihelion on August 27th and achieve maximum brightness on its outward trip below the Earth in September as it moves passed the head of Hydra. LINEAR is south of Piscis Austrinus and will continue southward into southern hemisphere morning skies in July as it drops away from Earth on its journey back to the Oort Belt.

Mars Landers

Opportunity is exploring southward on the west rim of Endeavour Crater. The rover is conducting a contact science campaign with rocks in the northern part of a the region of aluminum/hydroxyl clay minerals measured from orbit. Upon arrival at the hypothetical aluminum-hydroxyl clay mineral area Opportunity approached a region with extended rock outcrops to conduct detailed investigation for the presence of clay minerals which may preserve residues of organic chemistry. From Sol 3662 (May 13, 2014) to Sol 3710 (July 1, 2014) the rover traveled over 686 feet as it examined the area. Starting on Sol 3664 (May 15, 2014), the rover began its surface campaign in this region with the collection of a Microscopic Imager (MI) mosaic and the placement of the Alpha Particle X-ray Spectrometer (APXS) on the surface target, called Bristol Well, a light-toned vein. On Sol 3671 (May 22, 2014) the rover began investigation of Sarcobatus Flat and also continued with a process of correcting the spacecraft clock by a few seconds each day (sol) to gradually offset the accumulated drift since the beginning of the mission.

Between Sol 3674 (May 25, 2014) and Sol 3693 (June 14, 2014), a series of Flash memory amnesia events occurred. Each was followed by a Flash memory reset in which data was recovered so there were no impacts to operations and no loss of science data. Opportunity is in good health with proper wheel currents, ample energy and no resets or faults.

On Sol 3707 (June 28, 2014), a (MI) mosaic was collected of the surface target Sodaville, followed by analysis with the (APXS). Opportunity then collected a (MI) mosaic and (APXS) of the target Tuscaloosa and proceeded to investigate a target near Sodaville with another (MI) mosaic and (APXS). Solar array energy production was maintained at levels between 650 and 761 watt-hours per day during the 2 month interval.

In early May, NASA’s Curiosity Mars rover approached a rock layer surrounding the base of a small 16 foot tall butte called Mount Remarkable at “the Kimberley.” A sandstone slab in the "middle unit" called Winjana was targeted for the drilling after camera and X-ray spectrometer observations. The drilling produced a powdered sample from the rock's interior which was delivered to onboard laboratory instruments for chemical analysis in the middle of May. Principal investigator David Blake states that subsequent studies reveal that Windjana has more magnetite than previous samples analyzed causing the powder to be darker colored. “A key question is whether this magnetite is a component of the original basalt or resulted from later processes, such as would happen in water-soaked basaltic sediments....”

Preliminary indications are that the rock contains a more diverse mix of clay minerals than found in the mission’s only previously drilled rocks, the mudstone at Yellowknife Bay. Windjana also contains an unexpectedly high amount of the mineral orthoclase, a potassium-rich feldspar that is one of the most abundant minerals in Earth’s crust. It had never before been definitively detected on Mars. This implies that some rocks on the Gale Crater rim from which the Windjana sandstones may have been derived experienced complex geological processes such as multiple melting episodes.

On June 27, 2014, NASA Mars rover Curiosity drove out of the 4 mile by 12 mile ellipse mapped as safe terrain for its 2012 landing inside Gale Crater as it proceeded on its drive toward the long-term destination on the slopes of Mt. Sharp at the center of Gale Crater.

Meteor Showers

The Piscis Austridid Meteor Shower on the 28th is a minor shower emanating from close to Fomalhaut, the 1st magnitude star in Piscis Austrinus which is on the southern horizon for observers in the northern United States. The shower seldom achieves more than 5 meteors per hour.

The Southern Delta Aquarid Meteors will shower us an hour or two before dawn on the night of the 29th/30th with 15 to 20 meteors/hr. The shower coincides with the crescent waxing Moon which sets just after sunset. Lunar glare will be absent enhancing visibility of the meteors. The meteors are suspected to result from ices, dust, and other debris shed by Comet 96P Machholz which orbits the Sun every 5.3 years and was last at perihelion on July 14, 2012.

Planet Plotting

Jupiter, Mars, and Saturn are evening planets in July. Jupiter (-1.8) in Cancer sets soon after the Sun early in the month and is in conjunction with the Sun on the 24th. Mars (0.0) in Virgo sets slightly after midnight in early July and at about 11PM EDT on the 31st. Best viewing is an hour or so after sunset when it is relatively high in the southwestern sky. Saturn (+0.2) in Libra sets well after midnight on the 1st and about midnight at the end of the month. Mars is catching up with Saturn as it orbits the Sun, the gap between the two narrows from 28° to 12° during July. On the 12th, Mars lies within 1.5° of the first magnitude Spica in Virgo. The contrast in color between blue-white Spica and significantly brighter orange Mars produces a stunning sight in binoculars.

Mercury, Venus, Uranus, and Neptune are morning planets. Venus in Taurus is spectacular at magnitudes (-3.9 to -3.8) and nearby Mercury ranges from a relatively dim +2.5 magnitude in early July to a bright -1.4 magnitude at month's end. The two are within 6.2° of one another on the 16th. After reaching a maximum elongation of 21° from the Sun on the 12th, Mercury will maintain a brightness in excess of magnitude 0.0 for the remainder of July. Neptune (+7.8) in Aquarius and Uranus (+5.8) in Pisces are high in the southern sky before sunrise.

PlanetConstellationMagnitudePlanet Passages
SunGemini, Cancer-26.8New Moon, 7/26, 6:42PM EDT
MercuryTaurus, Gemini+2.5/-1.4Max. Western Elongation, 7/12, 2PM EDT
Venus, 6.2°ESE, 7/16, 7PM EDT
VenusTaurus, Gemini-3.9 to -3.8Mercury, 6.2°WNW, 7/16, 7PM ED
MarsVirgo0.0 to +0.4 
JupiterCancer-1.8 
SaturnLibra+0.4 to +0.5 
UranusPisces+5.8 
NeptuneAquarius+7.8 

July Moon

The New Moon on June 27th at 4:08PM EDT was the beginning of Lunation 1132 which ends 29.61 days later with the New Moon on July 26th at 6:42PM EDT.

July's Full Moon is in Sagittarius on the 12th at 7:25AM EDT. The July Moon was traditionally named "Summer Moon" in Colonial America. For Celts it was “Moon of Claiming.” Chinese call it “Hungry Moon." To Medieval English it was “Mead Moon.” Anishnaabe people (Odawa and Ojibwe) of northern Michigan call it “Aabita-niibino-giizis” (Raspberry Moon).

Lunar perigee, when the Moon is at the nearest point in its orbit (222,612 miles or 56.17 Earth Radii in July), occurs on the 13th at 4:26AM EDT. The highest tides of the month, which are known as Spring Tides, occur during New and Full Moon due to the lining up of the Moon and Sun which causes their gravitational attractions to act in the same direction. Statistical analyses reveal that earthquakes are more frequent during Spring Tides. Tidal surges around the world will be further enhanced in July by the proximity of Earth and Moon which intensifies this effect.

Apogee distance (maximum distance) is 252,629 miles (63.74 Earth Radii) from Earth on the 27th at 11:28PM EDT. This apogee is the most distant of the year so the Spring Tide due to New Moon (19 hours earlier) will be lower than normal.

PlanetConstellationMagnitudeMoon PassageMoon Phase/Age
SunGemini-26.86:42PM EDT, 7/26New ~ 0 days
MercuryGemini-0.95.0°S, 2PM EDT, 7/25Waning Crescent ~ 28.41 days
VenusGemini-3.84.0°S, 2PM EDT, 7/24Waning Crescent ~ 27.41 days
MarsVirgo0.00.2°N, 9PM EDT, 7/5Waxing Gibbous ~ 8.70 days
JupiterCancer-1.85.3°SSW, 8PM EDT, 7/26Waxing Crescent ~ 0.05 days
SaturnLibra+0.40.4°S, 10PM EDT, 7/7Waxing Gibbous ~ 10.74 days
UranusPisces+5.81.4°N, 6AM EDT, 7/18Waning Gibbous ~ 21.08 days
NeptuneAquarius+7.85.0°N, 1PM EDT, 7/15Waning Gibbous ~ 18.37 days




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