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June 2018 Skies

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June Skies

by Dick Cookman


Highlights: Comet Journal, Martian Landers, Meteor Showers, Summer Solstice, Planet Plotting, June Moon

Focus Constellations: Leo, Lynx, Camelopardalis, Cassiopeia, Cepheus, Ursa Minor, Draco, Ursa Major, Coma Berenices, Bootes, Corona Borealis, Hercules, Lyra, Cygnus, Aquila

Comet Journal

Ninth magnitude comet C/2016 M1 (PanSTARRS) is the only June comet exceeding 10th magnitude, but its extreme southerly position produces unfavorable views this year for northern observers. It is moving southward through Sagittarius and is best observed well after midnight. It will leave northern hemisphere skies in early June, long before its August perihelion.

Mars Landers

Opportunity is halfway down the approximately 656-feet (200-meter) Perseverance Valley on the west rim of Endeavour Crater, pursuing evidence for support of one of several hypotheses as to the origin of the valley. The rover has been driving to position itself for investigation of some tabular and vesicular rocks which have been the objective of the science team for several days (sols). On Sol 5070 (April 28, 2018), the robotic arm (IDD) achieved a position to reach some of the rock surfaces. A Microscopic Imager (MI) mosaic was collected on Sol 5072 (May 1, 2018) and the Alpha Particle X-ray Spectrometer (APXS) conducted a multi-hour integration to determine the elemental composition. With the rover adjacent to these rocks, the Panoramic Camera (Pancam) imaged close-up, color stereo arrays to fill out the investigation. As of Sol 5093 (May 22, 2018), solar energy production was 664 watt-hours. Total travel on Mars by Opportunity has now reached 28.06 miles (45.16 kilometers).

On April 20th, after a 3 month examination of Vera Rubin Ridge (Hematite Unit) on the flank of Mt. Sharp, Curiosity descended from the ridge in order to reexamine the layers immediately below the ridge and to test out a new drilling procedure on softer rocks. The rover then turned northward to traverse a rock strewn area underlain by the Blunts Point Member of the Murray formation to approach the distant Red Cliff. A large rock dubbed Duluth was chosen as the drilling target to test the new procedure developed to counter the failure of the drill feed mechanism in December 2016. The last two attempts failed due to insufficient force applied by rotation of the drill. The new drilling was successful on May 20th because a hammer drill component was added which allowed the drill to penetrate two inches into the rock. The next few sols were devoted to develop successful delivery of the drilling samples to the two laboratories within the rover which will conduct chemical and mineralogy analysis of the samples.

Meteor Showers

June’s meteor showers include the Aretids on the 7th and the Bootids on the 23rd. The Aretids peak a day after the 3rd quarter Moon and are an intense daytime shower producing a significant radio/radar signature. The shower is of uncertain parentage with the near-Earth asteroid 1566 Icarus and Comet 96/P Machholtz as likely candidates. Each has an orbit that resemble that of the shower.

The Bootids are a minor shower associated with Comet 7P/Pons-Winnecke. It peaks 3 days after the 1st quarter Moon and will experience major interference from the waxing gibbous Moon.

Summer Solstice

The solstice is at 6:51AM EDT on the 21st. Sol (sun) - stice (stands still) occurs at two places in Earth’s orbit. The northern hemisphere summer position is when Earth arrives at the orbital position where its axis is leaning toward the Sun, lighting up the northern hemisphere when the Sun is directly above 23.5° north latitude. The other position is where the axis tilts away from the Sun which is then directly above 23.5° south latitude causing southern hemisphere summer and northern hemisphere winter. Since our axis precesses, the orbital positions of the solstices change every year as one complete wobble takes 26,000 years. This is compounded as our elliptical orbit also precesses in the opposite direction, completing one complete rotation every 113,000 years. The combination results in a 21,000 year cycle of tilting away from and toward the Sun when positioned closest to and farthest from the Sun. This coincides with retreat and advance of continental glaciation which may also be influenced by the 45,000 year cycle of changing axial tilt and the 100,000 year cycle of variation of eccentricity of Earth’s orbit.

Planet Plotting

Brilliant Venus (-3.9 ) moves from Gemini, through Cancer, and into Leo in June like a beacon wandering through the evening southwestern sky between 1st magnitude Pollux in Gemini and 1st magnitude Regulus in Leo. In the latter part of the month, it will be trailed by Mercury which marches through Taurus, Gemini, and Cancer as it dims from magnitude -1.7 to 0.0 and rises up through the glow of sunset after its conjunction with the Sun on the 5th. A thin waxing crescent Moon will pass Mercury on the 14th and Venus on the 16th.

Jupiter (-2.43 to -2.32) rides high in Libra in the southern evening sky. It is dimming slightly from its brightest at opposition in May and will appear near the waxing gibbous Moon on the 23rd. In early June, Saturn (+0.2 to +0.0) in Sagittarius rises in the southeast about 10PM EDT and Mars (-1.2 to -2.1) in Capricornus rises two hours later and brightens drastically during June as it approaches a breathtaking opposition in July when it will be brighter than at any time since 2003. Both rise earlier each evening until the 27th when Saturn reaches opposition and is at its brightest for 2018. Mars appears to more than double in brightness and increase by a third in size in June as it approaches opposition in July. The waxing gibbous Moon appears to approach Saturn at midnight on the 28th, and Mars will receive two visits of the waning gibbous Moon, the 1st on June 3rd and the 2nd on the 30th.

Neptune (7.9) rises in Aquarius at about 2AM EDT on the 1st and about midnight at month’s end. It is near the waning gibbous Moon on the 6th. Uranus (+5.9) in Aries appears low in the eastern sky before dawn in the latter part of June. On the 9th, the waning crescent Moon approaches Uranus at 11PM EDT.

PlanetConstellation(s)MagnitudePlanet PassagesTime, Date
SunAries, Taurus-26.8New Moon3:43PM EDT, 6/13
MercuryTaurus/Gemini/Cancer-1.7 to 0.0Superior Conjunction10:00PM EDT, 6/5
VenusGemini/Cancer/Leo-3.9 to -4.1  
MarsCapricornus-1.2 to -2.1  
JupiterLibra-2.3 to -2.2  
SaturnSagittarius+0.2 to 0.0Opposition9:00AM EDT, 6/27
UranusAries+5.9 to +5.8  

June Moon

June’s New Moon on the 13th at 3:43PM EDT is the beginning of Lunation 1181 which ends 29.26 days later with the New Moon of July on the 12th at 10:48PM EDT. The Full Moon on the 28th at 12:53AM EDT is known as the “Rose or Flower Moon” and the “Strawberry Moon.” Celts called it “Moon of Horses,” and Colonial Americans called it “Rose Moon.” Chinese refer to it as “Lotus Moon,” and it was the “Dyan Moon” in Medieval England. Anishinaabe (Odawa and Ojibwe people) recognize it as “Odemiini-giizis” (Strawberry Moon.)

Lunar Apogee (maximum orbital distance) occurs on the 2nd at 12:35 PM EDT when the Moon is at 251,852 miles (63.55Earth radii). It is again at apogee (252,315 miles (63.66 Earth radii) at 10:43PM EDT on the 29th. Perigee (closest to Earth) is 223,385 miles or 56.37 Earth radii on the 14th at 7:53PM EDT.

PlanetConstellationMagnitudeMoon PassageMoon PhaseMoon Age
SunTaurus-26.83:43PM EDT, 6/13New0 days
MercuryGemini-1.24.6°S, 10:00AM EDT, 6/14Waxing Crescent0.76 days
VenusCancer-3.92.0°S, 9:00AM EDT, 6/16Waxing Crescent2.27 days
MarsCapricornus-1.33.0°N, 8:00AM EDT, 6/3Waning Gibbous19.01 days
MarsCapricornus-2.14.0°N, 10:00PM EDT, 6/30Waning Gibbous17.26 days
JupiterLibra-2.24.0°N, 3:00PM EDT, 6/23Waxing Gibbous9.97 days
SaturnSagittarius0.01.8°N, 12:00AM EDT, 6/28Waxing Gibbous14.35 days
UranusAries+5.95.0°S, 11:00PM EDT, 6/9Waning Crescent25.63 days
NeptuneAquarius+7.92.0°S, 2:00PM EDT, 6/6Waning Gibbous22.26 days


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