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June 2017 Skies


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June Skies

by Dick Cookman

05/29/2017


Highlights: Comet Journal, Martian Landers, Meteor Showers, Summer Solstice, Planet Plotting, June 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 in eastern Hercules at 8th magnitude after passing through perihelion in April and will dim to 12th or 13th magnitude by June 30th. It will move southward through eastern Ophiuchus into Serpens Caput in June as it starts its retreat to the outer asteroid belt. C2015 ER61 (PanSTARRS) is at 6th magnitude in Pisces after passing through perihelion on May 9th. It will move into Aries by the end of June as it decreases to 8th magnitude.

Comet V2 Johnson is at 7th magnitude in southern Bootes. It will brighten to 6th magnitude as it approaches perihelion on June 12th, then will move southward through eastern Virgo during June.

Mars Landers

Opportunity is on the western rim of "Endeavor Crater", the 14 mile wide crater located on "Meridiani Planum", the plain where the rover landed in January of 2004. Between Sol 4711 (April 25, 2017) and Sol 4738 (May 22, 2017), the rover imaged a few small "fresh" craters as it approached "Perseverance Valley" which cuts through the rim and descends to the bottom of the 984' deep crater. Since Sol 4720 (May 4, 2017), after arrival at the top of the wide spillway that tapers downhill into the channel at the center of the valley, Opportunity maneuvered around the top of the spillway to obtain wide-baseline stereo down-valley images for a detailed map revealing valley topography. The map is for planning a route down the valley to the floor of the crater. Solar array energy production averaged 394 watt-hours per sol and the rover has traveled 27.86 miles (44.8 kilometers) on Mars since 2004.

After scooping numerous samples of Bagnold Dune sand at the end of March, Curiosity moved farther through the dune field characterized by dark rock slabs with intervening sand patches and arrived at a position in front of the interesting “Moosehead Lake” outcrop with lots of veins and grey patches on Sol 1668-70 (April 14, 2017). The outcrop was examined with the Chemcam, Mastcam, and MAHLI cameras and the Science Laboratory moved to a curb of Murray bedrock for further observation on Sol 1674 (April 21, 2017). After studying another rock outcrop on Sol 1679 (April 26, 2017), the rover continued upward, testing bedrock composition at vertical intervals of 5 feet, toward Vera Rubin Ridge (initially called Hematite Ridge due to spectral hematite signatures obtained from orbit).

Meteor Showers

The Bootid Meteor Shower on the 23rd or 27th coincides respectively with the waning or waxing crescent Moon which rises just before or after dawn. Minimal lunar glare in the predawn hours enhances visibility of the meteors. Meteor rate has been extremely variable. Prior to 1927 it was a relatively consistent shower but was dormant from 1927 to 1998 when it produced up to 100 meteors per hour. In 2004 it appeared again with rates approaching 50 meteors per hour. The meteors result from debris thrown off by Come 7P Pons-Winneke which orbits the Sun every 6 years and was last at perihelion in 2016. Since the showers seem to occur when the comet is close to perihelion, there may not be much of a show by the relatively slow moving meteors.

Summer Solstice

The Summer Solstice is on June 21st at 12:24AM, slightly less than 3 days before New Moon. Since the axis of the Earth is inclined directly toward the Sun on the solstice, the Sun appears to be overhead at 23.5° north latitude at noon during the day of the solstice. At 45° north latitude the noon position of the Sun is 68.5° above the south point on the horizon (90°- 45° + 23.5°).

The night of the solstice is the shortest night of the year, the day is the longest. The Sun shines directly on the northern hemisphere of the Earth and less directly on the southern hemisphere causing northern hemisphere summer and southern hemisphere winter. The Earth is farthest from the Sun in early July which tends to moderate northern hemisphere summers and exaggerate winter in the southern hemisphere. This effect on average temperatures is counterbalanced by the moderating influence of widespread southern hemisphere oceans and the exaggerating effect of large northern hemisphere continents.

Planet Plotting

Morning planets include Mercury (-0.2 to -2.2 to -1.3) which moves through Aries and Taurus during June, and arrives in Gemini at month’s end. Venus (-4.3 to -4.1) tracks through Pisces and Aries, moving into Taurus in June. Uranus (+5.9) is in Pisces, and Neptune (+7.9) is in Aquarius. Mercury is on the other side of the Sun and is at Superior Conjunction on the 21st, then it moves to the evening sky. It pairs with the waxing crescent Moon on the 24th. Mercury will be separated from Mars by less than 1° in Gemini after sunset on the 28th. They might be visible in the west in the Sun’s glow. Venus is within 2° of Uranus on the 3rd and reaches maximum western elongation 7 hours later when it is 45.9° from the Sun in the morning sky. It is next to the Moon on the 20th. Saturn (+0.2 to -0.1 to +0.2) is in Ophiuchus in June. Adjacent to the Moon on the 9th, it brightens when approaching opposition on June 15th, then will dim slightly toward month’s end. Uranus and Neptune rise after midnight and are in the southern sky before dawn. The Moon is adjacent to Neptune on the 16th and Uranus on the 19th.

Evening planets in June include Mars (+1.9) in Taurus and Gemini. It is within 20° of the setting Sun on the 1st and closes to less than 10° by the 30th as it nears conjunction in July. It is near the waxing crescent Moon on the 24th. Jupiter (-2.2 to -2.0) in Virgo is in the south after sunset and sets after midnight.

PlanetConstellationMagnitudePlanet Passages
SunTaurus, Gemini-26.8New Moon, 6/23 10:32PM EDT
MercuryAries
Taurus
Gemini
-0.2 to -2.2 to -1.3Superior Conjunction, 9:55AM EDT, 6/21
Mars, 0.77°S, 6/28, 3PM EDT
VenusPisces
Aries
Taurus
-4.3 to -4.1Uranus, 1.7°NNW 6/3, 1AM EDT
Max. W. Elong. (45.9°), 6/3, 8AM EDT
MarsTaurus, Gemini+1.9Mercury, 0.77°N, 6/28, 3PM EDT
JupiterVirgo-2.2 to -2.0 
SaturnOphiuchus+0.2 to -0.1 to +0.2Opposition, 6/15, 5:15AM EDT
UranusPisces+5.8Venus, 1.7°SSE 6/3, 1AM EDT
NeptuneAquarius+7.9 

June Moon

The New Moon of June 23rd at 10:32PM EDT is the beginning of Lunation 1169 which ends 28.95 days later with the New Moon of July 23rd at 5:46AM EDT. The Full Moon of June in Scorpio occurs at 9:10AM EDT on the 9th. The June Moon is called the “Rose, Flower, or Strawberry Moon”. Colonial Americans preferred the former, calling it the “Rose Moon”. To the Celts it was the “Moon of Horses”, and Chinese refer to it as “Lotus Moon”. It was the “Dyan Moon” in Medieval England, possibly derived from the Roman goddess of the Moon and hunting. Anishinaabe (Odawa and Ojibwe) people in northern Michigan recognize it as "Odemiini-giizis" (Strawberry Moon).

Lunar Apogee position in orbit (maximum orbital distance) is at 252,507 miles (63.71 Earth radii) from Earth on the 8th at 6:21PM EDT. Perigee (closest to Earth) is 222,425 miles or 56.12 Earth radii on the 23rd at 6:52 EDT. The proximity of perigee and New Moon will produce higher than normal spring tides.

Cecil Adams’ response to : Is the Great Wall of China the only manmade object you can see from space?

".....Any number of man-made structures can be seen from space, provided we construe "structure" to mean "anything built." Many of these are things that look like long, straight lines when seen from afar, such as highways, railroads, canals, and of course walls. If the orbit is low enough you can see even more."

Recently a reader incorrectly stated that the only man-made object visible from Earth orbit was the Great Wall of China. You set him straight — but you may be interested to know the Wall is the only man-made object visible with the unaided human eye from the surface of the moon. The quarter-million miles does make a perceptible difference.

"According to NASA, the earth as seen from the moon takes up less than one degree of arc in the sky. Basically it looks like a big blue marble. No man-made detail can be seen at all; sometimes even the continents are barely distinguishable.

Tom Burnam, author of "More Misinformation" (1980), quotes a letter from astronaut Alan Bean on the subject: The only thing you can see from the moon is a beautiful sphere, mostly white (clouds), some blue (ocean), patches of yellow (deserts), and every once in a while some green vegetation. No man-made object is visible on this scale. In fact, when first leaving earth's orbit and only a few thousand miles away, no man-made object is visible at that point either.”

PlanetConstellationMagnitudeMoon PassageMoon Phase/Age
SunGemini-26.810:32PM EDT, 6/24New ~ 0 days
MercuryGemini-2.15.3°N, 5AM EDT, 6/24Waxing Crescent ~ 0.60 days
VenusAries-4.22.3°NNW, 5:12PM EDT, 6/20Waning Crescent ~ 26.06 days
MarsGemini+1.94.4°N, 2PM EDT, 6/24Waxing Crescent ~ 0.98 days
JupiterVirgo-2.22.2°SSW, 7:57PM EDT, 6/3Waxing Gibbous ~ 9.18 days
SaturnOphiuchus03.1°S, 9:25PM EDT, 6/9Waning Gibbous ~ 15.24 days
UranusPisces+5.83.9°NNW, 2PM EDT, 6/19Waning Crescent ~ 24.93 days
NeptuneAquarius+7.90.70°NNW, 9AM EDT, 6/16Waning Gibbous ~ 21.72 days


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