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June 2016 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: Lynx, Camelopardalis, Cassiopeia, Cepheus, Draco, Ursa Minor, Ursa Major, Bootes, Hercules, Lyra, Cygnus, Aquila, Ophiuchus, Libra, Virgo, Coma Berenices, Leo, Cancer

Comet Journal

Comet 252P/LINEAR (2016) is between Ophiuchus and Serpens Caput at magnitude 10.0 as it circles through Ophiuchus in June. It is rapidly dimming and will recede beyond Jupiter's orbit this summer.

Comet C/2013 X1 (PanSTARRS) is approaching 6th magnitude in southern hemisphere skies. It passed through perihelion on April 20th and will pass within 56 million miles of Earth between the orbits of Earth and Mars on June 21st. It will appear south of Sagittarius in Telescopium in morning skies for observers in southern United States.

Mars Landers

Opportunity is still tooling around Mars even though its long time compatriot Spirit is silent and was last heard from in March 2010 as it was positioning itself to survive the upcoming winter. Its demise after 6 years on Mars was not a failure but the conclusion of a spectacular series of successes! Despite having to overcome tremendous challenges, Spirit exceeded its planned mission lifetime by more than 20 times as it explored Gustev Crater, a vast impact scar filled with sediments deposited in an ancient lake. The rover uncovered rocks formed from the sediments which had high concentrations of carbonate, a substance requiring wet, non-acidic depositional environments. Although previous evidence indicated that there were many areas of wet, acid conditions, this was the first indication that Mars once had water which may have hosted abundant life. Spirit also discovered evidence for ancient volcanism in contact with water and found an almost pure silica deposit like those on Earth which are found associated with hydrothermal veins and hot springs, prime acid loving microbe environments.

On May 1, 2009 Spirit drove into the soft sand west of Home Plate at Troy, its final resting place. After the science team spent months trying to free the rover, it was converted to a stationary research station in January, 2010. The last contact occurred on March 22nd when Spirit was put into hibernation for the winter. It never woke again despite the magnificent efforts of the science team which concluded on May 25, 2011.

Opportunity is exploring Marathon Valley on the rim of Endeavour Crater investigating rock outcrops for the presence of clay minerals which may contain evidence of ancient life. It is currently engaged in seeking out specific rock outcrops to find evidence for clay minerals. Between Sol 4357 (Apr. 26, 2016) and Sol 4391 (May 31, 2016) the rover traveled about 0.1 miles as it moved from target to target at an outcrop designated as "Pierre Pinaut" collecting evidence with its Navigation and Panoramic cameras and performing Alpha Particle X-ray Spectrometer (APXS) measurements. At each drive location, the rover collects a 360-degree Navigation Camera (Navcam) panorama plus targeted multi-filter (color) Panoramic Camera (Pancam) panoramas.

During the interval, the solar array energy production ranged between 636 and 672 watt-hours/day, sufficient energy for full operations. Total distance traveled by Opportunity on Mars in the last 12+ years is 26.59 miles (42.79 kilometers).

After a torturous crossing, Curiosity finally descended the west flank of Naukluft Plateau, a 1/4 mile wide terrain of sandstone composed of ancient lithified sand dunes carved into ridges and knobs by millions of years of wind erosion.

Current plans are to cross the Bagnold Dune Field by heading south between isolated dunes on the east and the Murray Buttes on the west. From Sol 1355 to 1356, the rover conducted numerous observations with its ChemCam of targets in the Murray formation and made multispectral observations of the contact between the Murray and Stimson units. It resumed driving on Sol 1357 (May, 29, 2016) then stopped to conduct a drilling campaign of the Oudam bedrock target from Sol 1360 through Sol 1365 (June 6, 2016). Plans are to then continue the journey ascending Mt. Sharp.

Meteor Showers

The Bootid Meteor shower peaks on June 27th during the 3rd quarter Moon which rises in the east about midnight. Meteor counts are normally less than 5 per hour but reach 100 to 150 per hour in good years. The meteors appear to come out of Bootes which is in the western skies after midnight when more meteors are visible because we are on the leading face of the Earth as it plunges through the river of debris scattered in space from previous passages of Comet Pons-Winnecke which circuits the Sun every 6.37 years. It last passed through perihelion in Jan. 2015.

Summer Solstice

The Summer Solstice is on June 20th at 6:34PM EDT when the axis of the Earth is tilted toward the Sun at its maximum angle and the Sun crosses the sky during the day at its highest annual elevation above the southern horizon. Before 1975, the June solstice was on the 21st or 22nd, then on June 21st until 2012, after which it occurred on the 20th or 21st. On the 20th at solar noon the Sun is at the zenith at 23.5° N. latitude (Tropic of Cancer) and is 47° above the south horizon at 66.5° N. latitude. Those living farther north are in the land of the midnight Sun and those south of 66.5°S experience no daylit hours. At 45° N. latitude the Sun appears 68.5° above the southern horizon at solar noon.

Even though the longest day of the year (and the shortest night) for northerners is the June solstice when the Sun is highest in the sky, the Earth is farther from the Sun than normal because it is approaching the early July farpoint (aphelion) in its orbit. The resulting intensity of sunlight perpendicular to the Sun's rays is actually lower in June and July than in April and May, a happy circumstance for the Spring warm-up. Solar distance varies from 91.5 million at perihelion in January to 94.5 million at aphelion, but limited hours of daylight compensate for solar proximity in January as extensive daylight compensates for the more distant July Sun.

Of course, the opposite relationship exists for the southern hemisphere which theoretically producing hotter summers and cooler winters were it not for moderation by more extensive oceans in the southern hemisphere in contrast to the large area of continental land mass in the northern hemisphere. Plate tectonics will alter this land/ocean relationship in the future and change everything again for patient observers as the Sun joins in by doubling its output over the next few billion years.

Some astronomers hypothesize that the Sun is experiencing more stability than usual. There are other sun-like stars that exhibit significant changes in output, abruptly increasing, then shutting down to minimal intensity just a quickly. Many giant stars exhibit much more extreme changes, sometimes on a weekly basis, but the Sun is thought to be in a long, stable stage of life, gradually increasing in output. Our problem is that deep sky astronomical investigation is only ~200 years old and we don't have the long term data to really know the definition of stable when it comes to stars.

If you wake one morning and notice a very dim orb rising in the east, don't worry, dress warmly. If a megabright blazingly hot crescent peaks above the eastern horizon, call off that southern trip and consider the Yukon.

Planet Plotting

June's morning planets include Mercury (+0.8 to -1.5), Uranus (+5.9) in Pisces, and Neptune (+7.9) in Aquarius. Mercury reaches greatest western elongation on the 5th when it is 24° from the Sun and 6° above the eastern horizon an hour before sunrise. Venus was a morning planet in May, moves through Superior Conjunction on the other side of the Sun on the 6th, and is out of sight throughout month before moving into evening skies in July.

Three planets and a half dozen+ 1st magnitude stars decorate evening skies in June. Mars (-2.0 to -1.4) in Libra is almost as bright in early June as it was at opposition in May. The crescent and new phases of the Moon produce much less competing glare than in May. Mars in the southeast is about as bright as Jupiter (-2.1) in Leo in the southwestern evening sky and outshines both Saturn (+0.2) in Ophiuchus and red supergiant Antares(+1.0) in Scorpius. Saturn's Opposition is at 3AM EDT on the 3rd when it is at its brightest magnitude of 2016. Mars, Saturn, and Antares near the southeastern horizon after sunset form a conspicuous triangle which moves into southern skies in the late evening as Jupiter sets in the west.

PlanetConstellationMagnitudePlanet Passages
SunTaurus, Gemini-26.8New Moon 6/4, 11PM EDT
MercuryTaurus, Gemini+0.8 to -1.5Max. West Elong. 6/5, 5AM EDT
VenusTaurus, Gemini  
MarsLibra-2.0 to -1.4 
JupiterLeo-2.1 to -1.9 
SaturnOphiuchus+0.0 to +0.1Opposition, 6/3, 3AM EDT

June Moon

The New Moon of June 4th at 11PM EDT marks the beginning of Lunation 1156 which ends 29.33 days later with the New Moon on July 4th at 7:01AM EDT.

June's Full Moon is in Ophiuchus and occurs at 7:02AM EDT on the 20th. It is known as the Flower Moon, Rose Moon, Strawberry Moon, or Honey Moon and was referred to as the "Rose Moon" in Colonial America. Celts referred to it as “Moon of Horses” and Chinese call it “Lotus Moon." To Medieval English it was the “Dyan Moon” and Anishinaabe (Chippewa and Ojibwe) of northern Michigan celebrate it as “Odemiini-giizis” (Strawberry Moon).

Perigee distance is 224,402 miles or 56.62 Earth radii on the 3rd at 6:55AM EDT. The Moon is at the apogee position in orbit (maximum orbital distance) at 251,670 miles (63.50 Earth radii) from Earth on the 15th at 8:00AM EDT.

PlanetConstellationMagnitudeMoon PassageMoon Phase/Age
SunTaurus-26.811PM EDT, 6/4New ~ 0 days
MercuryTaurus+0.70.7°S, 6AM EDT, 6/3Waning Crescent ~ 27.60 days
VenusTaurus-4.04.9°S, 10PM EDT, 6/4Waning Crescent ~ 29.27 days
MarsLibra-1.77.0°N, 6AM EDT, 6/17Waxing Gibbous ~ 12.14 days
JupiterLeo-2.01.5°S, 4PM EDT, 6/11Waxing Crescent ~ 6.71 days
SaturnOphiuchus+0.13.0°N, 8PM EDT, 6/18Waxing Gibbous ~ 13.88 days
UranusPisces+5.92.0°S, 10AM EDT, 6/1Waning Crescent ~ 25.77 days
UranusPisces+5.93.0°S, 7PM EDT, 6/28Waning Crescent ~ 23.83 days
NeptuneAquarius+7.91.2°N, 9PM EDT, 6/25Waning Gibbous ~ 20.92 days


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