July Skies by Dick Cookman

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

Focus Constellations: Ursa Major, Draco, Ursa Minor, Camelopardalis, Cassiopeia, Cepheus, Cygnus, Aquila, Lyra, Hercules, Corona Borealis, Bootes, Coma Berenices, Canes Venatici

  • Comet Journals 

Comet C/2023 A3 (Tsuchinshan-ATLAS) is a 8th magnitude comet circling through Sextans. Perihelion passage is in late September when it may briefly attain naked eye visibility at 1st magnitude. It passes perigee (closest to Earth) on October 12, lighting up the western evening sky. It will then circle through the summer triangle in Aquila, Cygnus, and Lyra for the next 6 months as it retreats to the Oort Cloud. 

Comet 13P/Olbers (2024) is a short period 7th magnitude comet in Lynx and Leo Minor in July. It passed through perihelion on June 30 and will be closest to Earth on July 20.

  • Mars Landers 

The Insight Lander, which sent its final goodbyes in December, 2022, provided an enormous amount of scientific data. Scientists will be mining these measurements and others collected by NASA missions for decades. A dead rover/lander/orbiter is not the final story, hypothetical and theoretical interpretations come and go, but measurements are immortal! They can be used again and again to develop more accurate hypotheses and theories. Ingrid Daubar, an associate professor (research) of Earth, environmental and planetary sciences at Brown University, recently analyzed Martian seismic data collected by the Insight Lander and concluded that Mars experiences far more impacts from space debris than was previously thought. The ramifications of this discovery may be far-reaching, they could possibly change the way we estimate ages of solar system bodies. Crater count has long been one means of estimating age— the more craters per unit area, the older the terrain. Initial studies of measurements made by our celestial robots focused on the new and shiny, most obvious, easiest, or immediately interesting phenomena, more subtle investigations were left for the future. There is a plethora of info yet to be extracted from lunar rocks collected by the Apollo missions 55 years ago.

Meteor Showers

Two relatively minor meteor showers in late July are separated by the Delta Aquarids on the 27th. The Piscis Austrinids are a minor southern hemisphere shower on the 27th, and the Alpha CapricornIds are on the 29th.

July 27: Pisces Austrinids. Active July 15-August 10. Radiant 22h44m -30°, ZHR 5, 35 km/sec. Waning Gibbous Moon. Progenitor: ?.

July 27: Delta Aquarids. Active July 12-August 19. Radiant 22h3m -16°, ZHR 20, 41 km/sec. Waning Gibbous Moon. Progenitor: Comet 96P/Machholz and/or Asteroid 2003 EH1.

July 29: Alpha Capricornids. Active July 3-August 15. Radiant 20h28m -10°, ZHR 4, 23 km/sec. Waning Gibbous Moon. Progenitor: 169P/Neat, 2017 MB1 

  • Planet Plottings 

Mercury (0.4 to 1.1 in Cancer and Leo) and Venus (3.8 in Gemini, Cancer, and Leo) are evening planets in the western sky during July. On the 6th, the waxing crescent Moon passes Venus and, on the 7th, both planets appear between the Moon and the horizon. Mercury is located 3° below the Moon and Venus is hugging the horizon. Each moves higher in the sky during July. On the 22nd, Mercury is at greatest eastern elongation, 27° from the Sun. 

Early morning skies display Jupiter (-1.9 to -2.0) and Uranus (5.8) in Taurus and Mars (1.0 to 0.9, in Aries) on the eastern horizon before sunrise. The waning crescent Moon passes Mars on the 1st and the red planet is above Uranus until the 15th when it passes within less than a degree and drops below the giant outer planet. The waning crescent Moon passes Uranus on the 2nd and Jupiter on the 3rd. Saturn (1.0 to 0.9, in Aquarius) and Neptune (7.8, in Pisces) are higher in the south and are passed by the waning gibbous Moon on the 24th and 25th. 

At the end of July, the waning crescent Moon again passes Uranus, Mars, and Jupiter, the former on the 29th and the latter two on the 30th.

Planet Constellation(s) Magnitude Planet Passages Time Date
Sun Taurus -26.5 New Moon 6:58PM EDT 7/5
Mercury Gemini, Cancer, Leo -0.4 to 1.1 Max. East Elongation 3:00AM EDT 7/22
Venus Gemini, Cancer, Leo -3.8
Mars Aries, Taurus 1.0 to 0.9 Uranus, 0.6°S 7/15
Jupiter Taurus -1.9 to -2.0
Saturn Aquarius 1.0 to 0.8
Uranus Taurus 5.8 Mars, 0.6°N 7/15
Neptune Pisces 7.9
  • July Moon

The New Moon of July is in Gemini on the 5th at 6:58PM EDT. The New Moon marks the start of Lunation 1256 which ends 29.51 days later with the New Moon of August in Cancer on the 4th at 7:13AM EDT. The Full Moon on the 21st occurs at 6:17AM EDT on the boundary between Capricornus and Sagittarius. It is known as the Hay or Thunder Moon. Colonial Americans preferred to call it the “Summer Moon”. To Celts it was the “Moon of Claiming”, and Chinese refer to it as the “Hungry Ghost Moon”. Medieval English thought of it as the “Mead Moon”, and the Anishinaabe (Odawa and Ojibwe) people of northern Michigan recognize it as “Miin-giizis (Blueberry Moon). Ontario’s Earth Haven Farm presents cultural teachings explaining the cycle of life and nature of their 13 Grandmother Moons. “The seventh moon of Creation is Raspberry Moon, when great changes begin. By learning gentleness and kindness, we may pass through the thorns of its bush and harvest its fruit, knowledge that will help in raising our families.”

Lunar Apogee (maximum lunar distance) is on July 12 at 4:11AM EDT when the Moon’s distance is 251,259mi. (63.40 Earth radii). Lunar perigee (minimum lunar distance) is on the 24th when the Moon is at 226,749 mi. (57.21 Earth radii) at 1:41AM EDT.     

Planet Constellation Magnitude Moon Passages Moon Phase Moon Age
Sun Gemini -26.8 6:58AM EDT, 7/5 New 0 Days
Mercury Cancer -0.1 3.0°N, 3:00PM EDT, 7/7 Waxing Crescent 1.83 Days
Venus Gemini -3.8 3.8°NNE, 1:00PM EDT, 7/6 Waxing Crescent 0.75 Days
Mars Aries 1.0 5.0°N, 2:00PM EDT, 7/1 Waning Crescent 25.22 Days
Mars Aries 0.9 5.0°N, 7:00AM EDT, 7/30 Waning Crescent 24.50 Days
Jupiter Taurus -1.9 5.0°N, 4:00AM EDT, 7/3 Waning Crescent 26.81 Days
Jupiter Taurus -2.0 5.0°N, 8:00PM EDT, 7/30 Waning Crescent 25.04 Days
Saturn Aquarius 0.9 0.4°N, 11:00AM EDT, 7/24 Waning Gibbous 18.67 Days
Uranus Taurus 5.8 4.0°N, 6:00AM EDT, 7/2 Waning Crescent 21.10 Days
Uranus Taurus 5.8 4.0°N, 2:00PM EDT, 7/29 Waning Crescent 24.08 Days
Neptune Pisces 7.8 0.6° N, 5:00AM EDT, 7/25 Waning Gibbous 21.85 Days