May 2025 Skies
BY: DICK COOKMAN
Highlights: Comet Journal, Martian Landers, Meteor Showers, Planet Plotting, May Moon
Focus Constellations: Ursa Major, Draco, Ursa Minor, Cepheus, Cassiopeia, Camelopardalis, Lynx, Gemini, Cancer, Leo Minor, Leo, Coma Berenices, Virgo, Bootes, Corona Borealis, Hercules, Lyra
Comet Journals
Comet C/2023 A3 (Tsuchinshan-ATLAS) has dimmed to 12th magnitude in Cygnus and has moved far enough away that, as Earth moves around the Sun each year, the comet appears to move in ever diminishing spirals centered between Aquila and Hercules.
Comets are made of ices, dust, and rock and have cores ranging from less than a kilometer to 100’s of kilometers in diameter. They follow highly elliptical orbits which may reach the Asteroid, Kuiper, or Oort Belts at aphelion and are close to the Sun at perihelion where they heat up and blow off dust and gas, drastically increasing brightness. The side of the nucleus opposite from the Sun has a shadow zone where some of the gas and dust can hide, forming the comet tail. Bigger comets, with more gravitational energy, hold gas and dust more tightly and can approach the Sun more closely without disintegrating. Comet C/2025 F2 (SWAN) from the Oort Belt was a small, 8th magnitude comet discovered in late March which disintegrated in mid-April when it came too close to the Sun, disappointing observers who hoped for a bright apparition in the eastern predawn sky in Pegasus. Perihelion passage of the remnant is on May 1 when it will also be closest to Earth. Remaining gas and dust may be visible early in the evening near the horizon in the northwestern sky next to the Pleiades.
Mars Landers
Earth has a very active carbon cycle. Atmospheric carbon dioxide and that dissolved in water bodies is taken up by organic photosynthesizers and converted into sugars utilized in respiration to produce metabolic energy for growth of organisms which provide support for organisms higher on the food chain. Eventually, bacteria may break down the resulting biomass to carbon dioxide and other carbon compounds which either return to the atmosphere and water bodies or may end up in biologic sinks or as carbon or carbonates in geologic sinks. Until recently, similar sinks have not been found on Mars.
Editor Keith T. Smith summarized a new article in Science Magazine: Carbonates identified by the Curiosity rover indicate a carbon cycle operated on ancient Mars: “The Curiosity rover is gradually climbing a mountain located in Gale crater on Mars. Higher levels of the stratigraphy expose rocks that formed at later times. Tutolo et al. studied the composition of drill samples taken from a sulfate-rich layer (see the Perspective by Bishop and Lane). They found that the rocks contained abundant iron carbonate, which was invisible in previous orbital observations. If there are similar abundances of carbonate in other sulfate-rich layers across Mars, then those layers may contain a substantial reservoir of carbon dioxide extracted from the atmosphere. The carbonates found by the authors have partially decomposed, returning some carbon dioxide to the atmosphere: an ancient carbon cycle.
Meteor Showers
May 5: Eta Aquarids, Active Apr. 19-May 28, Radiant 22h32m -1°, ZHR variable, up to 60, 66 km/sec., Waxing Gibbous Moon, Progenitor: Comet 1P/Halley.
May 8: Eta Lyrids, Active May 3-May 12, Radiant 19h08m 44°, ZHR 3, 44 km/sec., Waxing Gibbous Moon, Progenitor: C/1983 H1 (IRAS-Araki-Alcock).
Planet Plottings
In May, shimmering Jupiter (-1.8) shines brilliantly, low in the evening northwestern sky in Taurus. Ruddy Mars (1.0 to 1.3) is much higher in Cancer and Leo. Subtle surface details of Jupiter are best viewed early in the month because the giant planet drops lower in the sky each evening as it approaches conjunction with the Sun in June. Immersion in the glow of sunset enhances telescopic views of these details due to the comparative reduction of the planet’s glare.
After dusk in early May the morning planets congregate and adorn the eastern horizon. Saturn (1.2 to 1.1), Neptune (+7.9), scintillating Venus (-4.4 to -4.2), and Mercury (1.0 to -2.1) all appear clustered together in Pisces. The first three are below the eastern fish and Mercury is closer to the horizon, farther to the northeast. it moves into Aries on the 11th. Venus is 2° from Neptune on the 3rd when the Moon and Mars are arrayed next to the Beehive star cluster in Cancer. Mercury’s Superior Conjunction with the Sun is on the 29th and Venus reaches its greatest western elongation of 46° from the Sun on the 31st. Uranus is entombed in the afterglow of sunset and at solar conjunction on the 17th.
May Moon
The New Moon of May is in Taurus on the 26th at 11:02PM EDT. It marks the start of Lunation 1267 which ends 29.81 days later with the New Moon on June 25 at 6:32AM EDT. The Full Moon on the 12th at 12:56PM EDT in Aries is the Flower, Rose, or Strawberry Moon. Colonial Americans called it the “Milk Moon”. To the Celts it was the “Bright Moon”. It is the “Dragon Moon” for the Chinese. Medieval English thought of it as the “Hare Moon”, and the Anishinaabe (Odawa and Ojibwe) people recognize it as Zaagibagaawi-giizis or Waabigwani-giizis (Budding or Flower Moon). They have stories about the spirits of spring (Ziigwan), late spring (Minookimi), and summer (Niibin). Spring is represented by the constellation Mishi bizhiw, the Great Lynx, and summer is represented by the constellation Nanaboujou, the Protecting Spirit or Sleeping Giant. Mishi bizhiw (who is also known as Curly Tail), is located west of Virgo in Cancer and in the head of Leo in the southeastern evening sky and (Nanaboujou) is within the constellation Scorpius which rises in the east before midnight. Ontario’s Earth Haven Farm presents cultural teachings of the Mississauga branch of the Anishinabek Nation including the cycle of life and nature of the 13 Grandmother Moons. “The fifth moon of Creation is Flower Moon, where all plants display their Spirit sides for all the world to see. This life giving energy is one the most powerful, healing medicines on Mother Earth. During this moon we are encouraged to explore our Spiritual essences. The Moon is at Lunar Apogee (maximum lunar distance of 252,428 mi. (63.69 Earth radii) on May 10 at 8:47PM EDT. Lunar perigee is on May 25 at 9:34PM EDT when the Moon is at 223,086 mi. (56.29 Earth radii).
The waxing crescent Moon passes Mars on the 3rd, the day before 1st quarter Moon. The waning crescent passes Saturn and Neptune on the 22nd and Venus on the 23rd, Before New Moon on the 26th, a slender waning crescent Moon passes Uranus. A slim waxing crescent Moon passes Mercury on the 27th. It last passed Jupiter on April 30 and repeats the process on May 28.
