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May 2017 Skies

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May Skies

by Dick Cookman



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

Focus Constellations: Leo, Cancer, Gemini, Auriga, Perseus, Cassiopeia, Cepheus, Cygnus, Lyra, Draco, Hercules, Bootes, Ursa Minor, Ursa Major, Camelopardalis, Lynx

Comet Journal

41P/Tuttle-Giacobini-Kresak is between Hercules and Lyra moving southeastward. It is at 6th magnitude, and is expected to reach 5th magnitude and possible naked eye visibility as it approaches and passes perihelion on the 12th.

C/2017 E4 (Lovejoy) is in Triangulum on the 1st and moves through Aries to the Pleiades in May. It approached 6th magnitude at perihelion on April 23rd. It is now less than 7th magnitude and rapidly dimming.

C/2015 ER61 (PanSTARRS) moves from Aquarius in April. It is at 7th magnitude and is expected to remain at that level until it passes through perihelion on May 9th.

Comet V2 Johnson is at 8th magnitude on the border of Hercules and Bootes on the 1st and moves southward through Bootes in May. It brightens to 6th or 7th magnitude as it approaches perihelion in early June.

Mars Landers

Between Sol 4677 (Mar. 21, 2017) and Sol 4711 (April 25, 2017), Opportunity continued its mission to reach "Perseverance Valley" which cuts through the rim of the 14 mile wide Endeavor Crater. During the month the relatively smooth southerly journey along the western edge of the crater covered 430 meters and brought the rover within 80 meters of the 183 meter long valley. Total travel for each sol was limited to 50 to 100 feet by frequent dust storms which limited observing distance for route planning by mission scientists. "Perseverance Valley" is an attractive target because it may have been carved by water or debris flows 3 to 4 billion years ago and may contain evidence of microscopic life similar to that found as fossils in Earth rocks of similar age. Solar array energy production averaged 417 watt-hours per sol, and total travel on Mars is now is 27.75 miles (44.66 kilometers).

While ascending the lower part of the flank of Mt. Sharp, Gale Crater's central peak, Curiosity explored the Murray Formation, the lowest and oldest of Mt. Sharp's rock layers. Based on evidence gathered so far, the peak is an erosional remnant of a sequence of stream, delta, and lake deposits derived from erosion of the crater rim. The sequence accumulated over millions of years and was probably many hundreds of feet thick. The mobile science laboratory systematically characterized the chemistry and mineralogy of the rock layers in order to understand how these properties vary with elevation and to reveal changing conditions in the geologic processes that formed them.

On Sol 1650 (Mar. 28, 2017) Curiosity collected a number of scoops of the sand at “Ogunquit Beach” to analyze using the CheMin and SAM instruments. The rover departed the "beach" in "Bagnold Dune Field" which covers part of the outcrop of Murray Formation rock and headed southeastward along a spur extending northwestward from Vera Rubin Ridge (formerly Hematite Ridge). The path meandered between slabby rocks with intervening small patches of dark sand. Analyses of numerous slabs, surrounding landscapes, and the atmosphere were conducted with the various onboard instruments.

Meteor Showers

The Eta Aquarid meteor shower will peak on May 6th. During the evening the waxing gibbous Moon interferes a bit with viewing. The best viewing time is after moonset in the hours before dawn when we are on the leading side of the Earth as it plunges into the river of debris shed by Comet 1P/Halley which last flew by in 1986. Up to 60 swift and bright meteors per hour may shoot out of Aquarius in the southeastern sky, often leaving persistent trains.

Planet Plotting

Mercury (+2.2 to -0.2) in Pisces and Aries, Venus (-4.5 to -4.2) in Pisces, Uranus (+5.9) in Pisces, and Neptune (+7.9) in Aquarius are the morning planets. Mercury will be separated from Uranus by 2.2° in Pisces on the 7th, when they may be seen in the east before sunrise. Mercury is on the other side of the Sun and provides an excellent apparition at maximum western elongation on the 17th (26°), after which it will get brighter and higher in the western skies as its phase waxes. It pairs with the waning crescent Moon on the 23nd. Venus is next to the Moon on the 22nd and displays a bright waxing crescent as it ascends in eastern morning skies in May. Uranus and Neptune rise after midnight and are in the southern sky before dawn.

Evening planets include Mars (+1.8 to +1.9) in Taurus which rises after the Sun and appears near the waxing crescent Moon on the 26th. It is approaching solar conjunction in July and can be found progressively closer to the Sun through May and June as it descends into its glow in early evening western skies. Jupiter (-2.2 to -2.1) in Virgo rises before sunset and sets in the wee hours. Saturn (+1.1 to +1.0) moves from Sagittarius and into Ophiuchus in May. It is getting brighter as it approaches opposition in June.

PlanetConstellationMagnitudePlanet Passages
SunAries, Taurus-26.8New Moon, 5/25 3:45PM EDT
MercuryPisces, Aries+2.2 to -0.2Uranus, 2.2°N 5/7, 8AM EDT
MercuryPisces+0.6Max. West Elongation, 5/17, 11PM EDT
VenusPisces-4.5 to -4.2 
MarsTaurus+1.8 to +1.9 
JupiterVirgo-2.2 to -2.1 
SaturnSagittarius, Ophiuchus+1.1 to +1.0 
UranusPisces+5.9Mercury, 2.2°S 5/7, 8AM EDT

May Moon

The New Moon of May 25th at 3:45PM EDT is the beginning of Lunation 1168 which ends 29.31 days later with the New Moon of June 23rd at 10:32PM EDT.

The Full Moon of May in Scorpio occurs at 5:43PM EDT on the 10th. The May Moon is called the “Milk Moon”, a name also utilized by Colonial Americans. It is also called the "Planting Moon". To the Celts it was the “Bright Moon”, and Chinese refer to it as “Dragon Moon”. It was the “Hare Moon” of Medieval England, and Anishinaabe (Odawa and Ojibwe) people in northern Michigan recognize it as "Zaagibagaa-giizis" (Budding Moon).

Lunar perigee (closest to Earth) is 221,989 miles or 56.01 Earth radii on the 26th at 1:20 EDT. Apogee position in orbit (maximum orbital distance) is at 252,428 miles (63.69 Earth radii) from Earth on the 12th at 20 EDT.

Cecil Adams’ response to : Do things get crazy when the moon is full?

"...when it comes to exerting any influence on humankind, the moon has a lot of competition. Researchers have calculated that a mother holding her baby exerts 12 million times the tide-raising force on the child that the moon does, simply by virtue of being closer.

Another thing to remember is that the tides don't occur just once or twice a month; they occur once or twice a day. What happens at full and new moon is that the earth, moon, and sun are lined up, resulting in higher tides than usual. (At full moon the earth is between the moon and sun; at new moon the moon is between the sun and the earth.) So when we talk about the influence of the full moon, we're really talking about the additional influence of the sun. But small though the moon's pull on the earth is, the sun's is only half as much.

Just to make sure about all this, a pair of admittedly skeptically scientists (Rotton and Kelly, 1985) did what they called a "meta-analysis" of 37 studies of the moon's effect on things like psychiatric admissions, suicides, crime, etc. They found that the moon accounted for no more than 3/100 of 1 percent of the monthly variation.

A new twist was recently given to lunar-effect theorizing by the discovery that positive and negative ions in the atmosphere have an effect on behavior (negative ions usually favorable, positives the opposite). It turns out that the positive ions are more abundant when the moon is full. However, the effect is slight compared to major sources of positive ions like air conditioning and air pollution.

So how do we explain all those cops and emergency room nurses who believe in the lunar effect? Easy. Nobody notices when there's a full moon and nothing happens — you only notice when something does happen. In other words, heads I win, tails don't count. Case closed."

Dick Cookman's addendum: Additional light provided by the full moon has also been put forward as an explanation for the lunar-effect as a more visible landscape provides incentive to go outside and engage in activities which for some may prove to be antisocial or dangerous and produce unfavorable consequences. This situation was certainly more important before the advent of artifical outdoor lighting and may explain current attitudes based upon traditional views.

PlanetConstellationMagnitudeMoon PassageMoon Phase/Age
SunTaurus-26.83:45PM EDT, 5/25New ~ 0 days
MercuryPisces+0.21.5°SSE, 10PM EDT, 5/23Waning Crescent ~27.57 days
VenusPisces-4.42.3°SSE, 10AM EDT, 5/22Waning Crescent ~26.07 days
MarsTaurus+1.85.3°S, 11PM EDT, 5/26Waxing Crescent ~1.22 days
JupiterVirgo-2.32.0°NNE, 7PM EDT, 5/7Waxing Gibbous ~11.45 days
SaturnOphiuchus+1.13.1°NNE, 7PM EDT, 5/13Waning Gibbous ~ 17.45 days
UranusPisces+5.93.7°SSE, 3AM EDT, 5/23Waning Crescent ~28.78 days
NeptuneAquarius+7.90.46°S, 2AM EDT, 5/20Waning Crescent ~23.74 days

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