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The Skies of August, 2020


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The Skies of August, 2020

by Dick Cookman

August 7, 2020

 

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

Focus Constellations: Coma Berenices, Bootes, Ursa Major, Draco, Ursa Minor, Perseus, Andromeda, Pegasus, Cassiopeia, Cepheus, Cygnus, Aquila, Lyra, Ophiuchus, Hercules, Corona Borealis

Comet Journals

Comet C/2020 F3 (NEOWISE) moved away from Ursa Major and is in Coma Berenices in early August. It is tracking sub-parallel to the ecliptic and will be in Virgo at the end of the month when it will drop to 10th magnitude. After reaching almost 1st magnitude in July, it has already dimmed to 5th magnitude as it passes high above the orbit of Venus and departs from the inner solar system.

Comet C/2017 U6 (Lemmon) is at 9th magnitude as it leaves Coma Berenices in early August and enters Bootes. It will pass above Arcturus in mid-month as it approaches Corona Borealis in September and Hercules in October. It will rapidly dim as it returns to the Oort Cloud.

Comet 88P/Howell (2020) is in Virgo and will move along the ecliptic into Libra in late August. It is at 9th magnitude and will probably brighten to 8th magnitude as it approaches perihelion in Scorpius in late September. It is a short period comet with an aphelion slightly inside the orbit of Jupiter and a perihelion inside the orbit of Mars.

Mars Landers

InSight is the first Mars mission specifically dedicated to uncovering the secrets beneath the surface. It landed on Mars in November 2018 and set up its seismometer. Insight detected a quake in April, 2019 and has detected over 450 “marsquakes” so far. Insight’s heat probe is a 16-inch-long (40-centimeter-long) spike “mole” equipped with an internal hammering mechanism. After months of failed attempts to successfully drill to a depth where internal heat can be measured, mission scientists developed successful techniques to proceed with slow burrowing to the desired depth. Meanwhile, Rice University seismologists Alan Levander and Sizhuang Deng determined from seismometer data that there is a 22 mile deep boundary between the crust and mantle of Mars. A second boundary is a transition zone within the mantle where magnesium iron silicates undergo a geochemical change. Above the zone, the elements form a mineral called olivine, and beneath it, heat and pressure compress them into a new mineral called wadsleyite. Known as the olivine-wadsleyite transition, this zone was found 690-727 miles beneath InSight. “The temperature at the transition is an important key to building thermal models of Mars,” Deng said. “From the depth of the transition, we can easily calculate the pressure, and with that, we can derive the temperature.” The third boundary he and Levander measured is the border between Mars’ mantle and its iron-rich core, which they found about 945-994 miles beneath the lander. Better understanding this boundary “can provide information about the planet’s development from both a chemical and thermal point of view,” Deng said.

Curiosity is on the border Glen Torridon, the clay-bearing unit in the valley adjacent to Vera Rubin Ridge on 16,404 foot Mt. Sharp at the center of Gale Crater, the ancient remnant of a massive impact. On Sol 2778 (May 29), after the March drive up onto younger rocks of the Greenheugh pediment which is beyond and above the valley, Curiosity was directed to hit the road again, descend from the pediment, and head toward the “sulfate bearing unit” farther up the slopes of Mt. Sharp. After brief stops at a landslide at the base of the pediment scarp and at Bloodstone Hill, a light toned mound at the eastern edge of the pediment, the 1.5 km. trek to the sulfate unit ensued. The journey encompassed a slight descent into a boulder strewn lowland comprised of relatively soft, fine grained bedrock. After two months of determined driving interrupted by short pauses for gathering data about the surroundings, the rover arrived at the next drilling site named after Mary Anning who discovered the first full Ichthyosaur and the first Plesiosaur on the southern coast of England and whose early 1800’s discoveries were appropriated by male scientists who here shall remain nameless. On Sol 2839 (August 2, 2020), Curiosity‘s 27th drill hole was completed on the Mary Anning outcrop and the drilled sample was examined to ensure that it is good to deliver to CheMin and SAM for analysis. SAM analysis generates gases which are analyzed for organics. ChemCam chemical measurements of the drill hole were also planned in order to document rock chemistry at depth. Mastcam multispectral and ChemCam passive observations of the drill tailings also yields a complementary spectral assessment of the mineralogy of the drilling powder.

Meteor Showers

There are 3 meteor showers in August. The best is the Perseid shower on the 12th which has to compete with the waning crescent Moon in Taurus. The two other showers are relatively weak, with the Kappa Cygnids in southern skies. The Iota Aquarids are also buried in southern hemisphere skies as are three additional showers at the end of July.

  • August 12: Perseids. Active July 17-August 24. Radiant 3h04m +57°, ZHR variable 75-110+. 59 km/sec. Waning Crescent Moon. Progenitor: Comet 109P Swift-Tuttle, a comet orbiting the Sun once every 130 years, last at perihelion in 1992.
  • August 18: Kappa Cygnids. Active August 3-25, Radiant 19h04m +59°, ZHR 3, 25 km/sec. Last Quarter Moon. Progenitor: The meteor shower and Minor planet 2008 ED69 are thought to be remnants of a comet break up between 4000-1600 BC.
  • August 20: Iota Aquarids. Active August 11-31, Radiant 21h48m -06°, ZHR Variable 3, 31 km/sec. Waning Crescent Moon. Progenitor: Likely to be a dead comet broken apart into a number of NEO’s (near Earth objects).

PlanetConstellation(s)MagnitudePlanet PassagesTimeDate
SunCancer – Leo-26.8New Moon10:42PM EDT8/18
MercuryGemini – Leo-0.8 to -0.6Superior Conjunction11:00AM EDT8/17
VenusTaurus – Gemini-4.3 to -4.1Max. West Elongation – 46°8:00PM EDT8/12
MarsPisces-1.1 to -1.8Perihelion5:00AM EDT8/3
JupiterSagittarius-2.6 to -2.4   
SaturnSagittarius+0.2 to +0.3   
UranusAries+5.8 to +5.7   
NeptuneAquarius+7.8   

Planet Plotting

August evening skies feature Jupiter (-2.6 to -2.4) and Saturn (+0.2 to +0.3) in Sagittarius. Neptune (+7.8) in Aquarius rises about 10:00PM EDT and Mars (-1.1 to -1.8) in Pisces, makes its appearance around midnight.

Uranus (+5.8 to +5.7) in Aries rises slightly after midnight and Venus (-4.3 to -4.1) in Taurus and Gemini begins its predawn dominance about 4:00AM EDT. On the 12th Venus achieves maximum western elongation from the Sun when it rises at its earliest and is highest in the predawn sky. Mercury (-0.8 to -0.6) in Gemini and Leo is briefly visible very early in the month but disappears behind the Sun as it moves to Superior Conjunction on the 17th.

Mars repeats its July leap in apparent size and brightness in August as it approaches Opposition in October. The 2020 opposition finds Mars slightly beyond to its perihelion (closest to the Sun) position as the Mars perihelion is on August 3. Since Earth just moved by aphelion on July 4, Mars will be at a relatively close 38+ million miles (~75% as far as it is right now). The apparent diameter of Mars will increase about 33% between now and October, making the disk appear almost twice as large as it is currently and brightness will increase almost 4 times. Nevertheless, Mars is starting to become an awesome sight through even smaller telescopes and will get better and better as October draws near. Mars will also rise earlier each evening until it makes it into the world of those who practice early to bed, early to rise.

The waxing gibbous Moon is 1.4° from Jupiter at 8:00PM EDT on the 1st, and 2.0° from Saturn at 9:00AM EDT on the 2nd. It is 1.4° from Jupiter at 10:00PM EDT on the 28th and 2.0° from Saturn on the 29th. The waning gibbous Moon is within 4.0° of Neptune at 11:00AM EDT on the 6th, 0.8° from Mars on the 9th, and 4.0° from Uranus on the 10th. The waning crescent Moon is 4.0° from Venus on the 15th and a waxing crescent Moon is 2.7 ° from Mercury on the 19th.

August Moon

The New Moon of August on the 18th at 10:42PM EDT is the beginning of Lunation 1208 which ends 29.36 days later with the New Moon on September 17 at 7:00AM EDT. The Full Moon of August is on the 3rd at 11:59AM EDT. It is commonly known as the “Green Corn or Grain” Moon and was called the “Dog’s Day Moon” in colonial times. In Medieval England it was the “Corn Moon.” Celts named it the “Dispute Moon” and the Chinese call it the “Harvest Moon”. Anishinaabe (Odawa and Ojibwe) people recognize it as “Manoominike-giizis” (Ricing Moon).

Lunar Apogee (maximum orbital distance) is on August 9 at 9:50AM EDT when the Moon’s distance is 251,444 miles (63.45 Earth radii). Perigee is on the 25th at 1:02AM EDT when the Moon is 228,889 miles from Earth (57.00 Earth radii).

PlanetConstellationMagnitudeMoon PassagesMoon PhaseMoon Age
SunTaurus-26.810:42PM EDT, 8/18New0 days
MercuryLeo-1.62.7°NNE, 2:00AM EDT, 8/19Waxing Crescent0.15 days
VenusGemini-4.24.0°N, 9:00AM EDT, 8/15Waning Crescent25.44 days
MarsPisces-1.30.8°S, 4:00AM EDT, 8/9Waning Gibbous19.23 days
JupiterSagittarius-2.6
-2.4
1.5°S, 8:00PM EDT, 8/1
1.4°S, 10:00PM EDT. 8/28
Waxing Gibbous
Waxing Gibbous
11.90 days
9.98 days
SaturnSagittarius+0.2
+0.3
2.0°S, 9:00AM EDT, 8/2
2.0°S, 1:00PM EDT, 8/29
Waxing Gibbous
Waxing Gibbous
12.44 days
10.61 days
UranusAries5.84.0°S, 5:00PM EDT, 8/10Waning Gibbous20.77 days
NeptuneAquarius7.94.0°S, 11:00AM EDT, 8/6Waning Gibbous16.52 days


  • Garry, Cosmo Geezer, harshad.savant and 2 others like this


3 Comments

Thanks

Photo
DakotaHoosier
Sep 01 2020 11:43 AM

New here. That's a great write-up! Thanks for sharing such an information dense, relevant write-up.

Thank you DC! This was very useful last month!



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