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August 2019 Skies
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by Dick Cookman
Highlights: Comet Journal, Martian Landers, Meteor Showers/Asteroid Surprises, Planet Plotting, August Moon
Focus Constellations: Bootes, Corona Borealis, Ophiuchus, Hercules, Lyra, Aquila, Pegasus, Cygnus, Draco, Cepheus, Cassiopeia, Perseus, Camelopardalis, Ursa Minor, Ursa Major
C/2018 W2 (Africano) was discovered on Nov. 27, 2018, and is a 9th magnitude comet in Camelopardalis moving northeastward during the first two weeks of August. It then turns southward and approaches Perseus by the 31st. It is at perihelion on September 5, 2019, and may be at magnitude 9. It is closest to Earth on the 27th when in Pegasus.
C/2018 N2 (ASASSN) is an 11th magnitude comet moving northward in Aries which rises after midnight and slowly moves through northern skies for the next two years. At perihelion on November 11 in Andromeda, the comet will probably not exceed 10th magnitude in brightness as it moves perpendicular to the plane of the solar system between Mars and Jupiter.
C/2017 T2 (Panstarrs) is a 12th magnitude comet in Taurus which deserves mention because it will brighten as it moves northward and westward into Cassiopeia by March and April of 2020 when it may approach naked eye visibility.
The Insight lander arrived on Elysium Planita of Mars on Nov 26, 2018. After unfurling the solar panels and radio antenna and deploying its seismometer, the mole carrying the Heat Flow and Physics Properties Package (HP3) began burrowing into the ground on Feb. 28, aiming to reach a depth of up to 16 feet (5 meters). But it became stuck at a depth of 30 centimeters, possibly due to an obstruction or other issue. On June 28, InSight’s robotic arm, designed to place instruments onto the Martian surface, lifted the support structure for the HP3 and uncovered the mole as part of efforts to troubleshoot the instrument. By carefully selecting a landing site that had both fewer rocks in general and smaller ones near the surface, mission scientists hoped to avoid hitting a large rock because the robotic arm's grapple isn't designed to lift the mole once it's out of its support structure, so the mole can’t be relocated if a rock is blocking it. Testing at JPL and the German Aerospace Center (DLR) determined that the soil may not provide the kind of friction for which the mole was designed. Without friction, the mole would simply bounce in place instead of digging. “…images coming back from Mars confirm what we've seen in our testing here on Earth," said HP3 Project Scientist Mattias Grott of DLR. "Our calculations were correct: Cohesive soil is compacting into walls as the mole hammers.” Pressing on the soil near the drill pit with a small scoop on the end of the robotic arm may collapse the pit and provide the friction for the mole to dig. Regardless of the heat flow probe issues, the mission of Insight on Mars is proceeding as planned. On December 7, 2018, the Seismic Experiment for Interior Structure (SEIS) instrument recorded sounds of Martian winds. Winds were detected by recording vibrations coming from the lander’s large solar arrays. On April 6, the same instrument detected a small, but long-duration tremor coming from the planet’s interior. This event, along with many other “marsquakes” detected by this instrument, lends credibility to the assumption that Mars may have an active, liquid center.
In its continuing quest for evidence of past or present life on Mars, Curiosity Rover is investigating Glen Torridon, the clay-bearing unit adjacent to Vera Rubin Ridge on 16,404 foot Mt. Sharp at the center of Gale Crater. Curiosity drilled into a site in the clay-bearing unit nicknamed Aberlady on Sol 2370 (April 6), and again on Sol 2384 (April 21, 2019), Rock powder was then obtained from an adjacent clay rich rock drilled at Kilmarie. After completion of drilling, the rover spent most of June and July traversing through Glen Torridon, examining pebbles and rocks, rippled sand, and ridges with bedrock layers at the surface of the clay-bearing unit. In late June, atmospheric methane levels temporarily spiked by 20 times — the largest amount of the gas Curiosity has ever found — from a transient methane plume like those observed in the past. While scientists have observed the background levels rise and fall seasonally, they haven't found a pattern in the occurrence of these transient plumes. "The methane mystery continues," said Ashwin Vasavada, Curiosity's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. Curiosity doesn't have instruments that can definitively say whether the source of the methane is biological or geological.
Meteor Showers, Asteroid Surprises
The best meteor shower of August if not the year is the Perseid Shower which averages 75 to 100 meteors per hour in dark skies free of light pollution. Meteors and fireballs emanate out of the NNE in predawn hours following setting of the waning gibbous Moon. Although the peak is on the morning of the 13th, the Moon sets earlier on the 12th, providing a longer viewing time before dawn.
- August 4: Iota Aquarius South. Active July 15-Aug 15. Radiant 22h12m -15°. ZHR 2. 34 km/sec. Waxing Crescent Moon. Progenitor: Likely to be a dead comet broken apart into a number of NEO’s (near Earth objects).
- August 8: Delta Aquarids North Active July 15-Aug 25. Radiant 22h20m -05°. ZHR 4. 42 km/sec. Waxing Gibbous Moon. Progenitor: Comet 96P/Machholz
- August 12-13 (both mornings): Perseids. Active July 17-Aug 24. Radiant 20 & 22h. ZHR 75 to 100+. 59 km/sec with numerous fireballs. Waxing Gibbous Moon. Progenitor: Comet Swift-Tuttle. Favorable after moonset.
- August 18: Kappa Cygnids. Active Aug 3-Aug 25. Radiant 19h04m +59°. ZHR 3. 25 km/sec. Waning Gibbous Moon. Progenitor: May be fragments associated with Asteroid 1996 JG
- August 20: Iota Aquarius North. Active Aug. 11-Aug 31. Radiant 21h48m -06°. ZHR 3. 31 km/sec. Waning Gibbous Moon. Progenitor: Likely to be a dead comet broken apart into a number of NEO’s (near Earth objects).
Asteroid 2019 OK passed within 45,000 miles of Earth on July 25 resulting in our avoiding Close Encounters of the Worst Kind. It was probably as wide as a football field is long and traveling almost 15 miles/sec. "It snuck up on us pretty quickly," Melbourne-based observational astronomer Mike Brown said. "People are only sort of realizing what happened pretty much after it’s already flung past us.” Although it wasn’t a 5 to 10 mile wide planet killer, and no other asteroid is “expected” to pass closer than the Moon’s distance in the next month, its passage serves to remind us that, in the big picture, the political and economic concerns with which we fill our lives fade into insignificance.
August starts with Mercury (+1.9) in Gemini, Uranus (+5.7) in Aries, and Neptune (+7.8) in Aquarius as predawn planets. At the end of the month Mercury will be much brighter (-1.6) in Leo, Uranus will be slightly brighter (+5.7) and Neptune will not change in brightness. Mercury rises about 1.5 hours before the Sun on the 9th when it is at maximum western elongation (19°) from the Sun. It is well above the ENE horizon for the next week then drops rapidly into the glow of dawn. Uranus and Neptune rise in the evening and are visible the rest of the night. Saturn (+0.2 to +0.3) in Sagittarius rises and sets before sunset and sunrise respectively and Jupiter (-2.3 to -2.1) in Ophiuchus is also up before sunset and sets before Saturn. Venus (-3.8) and Mars (+1.8 to +1.7) in Leo are lost in the glow of sunrise and sunset throughout the month with Venus reaching conjunction with the Sun on the 14th and Mars at conjunction on September 2.
The waxing gibbous Moon is 2.0° from Jupiter at 7:00PM EDT on the 9th and 0.4° from Saturn at 6:00AM EDT on the 12th. A waning gibbous Moon is 4° from Neptune at 9:00AM EDT on the 17th and 5.0° from Uranus at 11:00AM EDT on the 21st. The waning crescent Moon is 1.86° from Mercury on the 29th, 2.91° from Mars at 9:00AM EDT on the 30th, and 2.79° from Venus at 3:00PM EDT on the 30th.
|Planet||Constellation(s)||Magnitude||Planet Passages||Time, Date|
|Sun||Cancer, Leo||-26.8||New Moon||6:37AM EDT, 8/30|
|Mercury||Gemini, Leo||+1.9 to -1.6||Max. West Elongation||7:00PM EDT, 8/9|
|Venus||Cancer, Leo||-3.8||Superior Conjunction|
|2:00AM EDT, 8/14|
2:00PM EDT, 8/24
|Mars||Leo||+1.8 to +1.7||Venus, 0.29°NNE||2:00PM EDT, 8/24|
|Jupiter||Ophiuchus||-2.3 to -2.1|
|Saturn||Sagittarius||+0.2 to +0.3|
|ranus||Aries||+5.8 to +5.7|
The New Moon of August on the 30th at 6:37AM EDT is the beginning of Lunation 1196 which ends 28.96 days later with September’s New Moon on the 28th at 2:27PM EDT. The August Full Moon is on the 15th at 8:29AM EDT. It is known as the “Green Corn, or Grain Moon”. Colonial Americans called it the “Dog’s Day Moon” because, to the Greeks and Romans, the “dog days” occurred in July and August when Sirius in Canis Major appeared to rise just before the Sun. Celts called it the “Dispute Moon” and it was named the “Corn Moon” in Medieval England. Chinese refer to it as the “Harvest Moon” and the Anishinaabe (Odawa and Ojibwe) people recognize it as “Manoominike-giizis” (Ricing Moon.)
|Planet||Constellation||Magnitude||Moon Passages||Moon Phase||Moon Age|
|Sun||Leo||-26.8||6:37AM EDT, 8/30||New||0 days|
|Mercury||Leo||+1.6||1.86°NNE, 11:00PM EDT, 8/29||Waning Crescent||28.32 days|
|Venus||Leo||-3.8||2.79°NNE, 3:00PM EDT, 8/30||Waxing Crescent||0.33 days|
|Mars||Leo||+1.8||2.91°NNE, 9:00AM EDT, 8/30||Waxing Crescent||0.08 days|
|Jupiter||Ophiuchus||-2.4||2.0°N, 7:00PM EDT, 8/9||Waxing Gibbous||8.16 days|
|Saturn||Sagittarius||+0.1||0.4°S, 6:00AM EDT, 8/12||Waxing Gibbous||10.49 days|
|Uranus||Aries||+5.8||5.0°S, 11:00AM EDT, 8/21||Waning Gibbous||19.82 days|
|Neptune||Aquarius||+7.8||4.0°S, 9:00AM EDT, 8/17||Waning Gibbous||15.74 days|
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