The Sky Above You – May 2024

By theorkneynews on May 1, 2024 • ( Leave a comment )

The Moon will be New on May 8^th, and Full on May 23^rd. The Moon passes Jupiter on the early evening of the 10^th, and although it passes all the other normally visible planets, none of them will be visible. This month, unusually, there are no planets visible in the morning and evening sky, until the very end, when Saturn and Mars will be low in the morning sky on May 31^st, with the waning Moon near Saturn. The Moon doesn’t even pass many bright stars, though it will be near Castor and Pollux in Gemini on the 12^th, when at First Quarter (half-full, waxing) and very close to Antares in Scorpius when it’s Full on the 23^rd.

In ‘The Green Children of Woolpit, Part 2’ (ON, June 26^th, 2022), I discussed the event of June 18^th, 1178 when, according to the chronicler Gervase of Canterbury, five or more men apparently witnessed the flare from an impact on the Farside of the Moon, forming the crater Giordano Bruno – 12 impacts in 30 minutes. Patrick Moore and H.P. Wilkins deduced the crater’s existence from the rays of impact debris, reaching the hemisphere facing Earth. Sydney Jordan produced a dramatic painting of it for my book Children from the Sky (Mutus Liber, 2012, Fig. 1).

Fig. 1. 1178 lunar Farside impacts, by Sydney Jordan for ‘Children from the Sky’

The monks claimed to have seen ‘red sparks’ flying off from the Moon, and allegedly they couldn’t have seen ejecta at that distance. The crater was photographed by Clementine, Kayuga-Selene, and in detail by Lunar Reconnaissance Orbiter (Fig. 2).

Fig. 2. Giordano Bruno crater from LRO overhead, 17th August 2023

The Kayuga-Selene images were used to estimate the age of the crater, by the number of smaller craters on the ejecta blanket immediately surrounding it, giving an age of approximately 4 million years, ‘much too old for the [1178] hypothesis’, says Wikipedia. But in ‘The Lunar Farside’ (ON, 4^th June 2023), I pointed out that if the monks’ account is correct, and there were 12 impacts in rapid succession, then the ejecta from the multiple events would have been superimposed and it would make the main crater look much older. It had been suggested that the asteroid 1991 VG might have been blasted off the Moon by the impacts, and the same suggestion was made for another discovery, 1999 CG9. But in April 2016 an ‘Earth co-orbital’ was found in an orbit giving recurring encounters with the Earth, making it a ‘quasi-satellite’ (Dave Adalan, ‘Was asteroid Kamo’oalewa blasted from this moon crater?’, EarthSky, online, April 25^th 2024). Orbital eccentricities suggest that it reached that position 1-10 million years ago, and spectral data suggests it’s of the same rock type as Giordano Bruno. We may know more soon, because the Chinese probe Tianwen-2 is scheduled to return samples from Kamo’oalewa within 2.5 years after its 2025 launch. We can also expected more accurate orbital data for it, from NASA’s NEO Surveyor telescope, to be launched in 2027. But we should keep in mind that Giordano Bruno is only the most likely, at present, out of a number of candidate craters.

The planet Mercury is invisible this month, even though it’s at maximum elongation from the Sun on the 9^th.

Venus is still out of sight beyond the Sun, at conjunction on the far side of it during June.

Mars will rise about 4 a.m. at the end of May, so it’s not likely to be seen in Scotland’s pre-solstice twilight. After a long-drawn-out farewell, the Perseverance rover has finally lost touch with the stranded Ingenuity helicopter (see ‘Space Notes – May 2024’, ON, pending). Perseverance has turned aside from the ancient riverbed piercing Jezero crater, to examine a rock on the inner rim called ‘Bunsen Peak’ (after a feature in Yellowstone National Park). Perseverance has taken two samples from it, by drilling and abrasion (Fig. 3); analysis of the latter shows it to be composed almost entirely of carbonate material, bound by nearly pure silica, and it’s thought to have formed on the shore of the lake which once filled Jezero, and to be particularly likely to contain evidence of life. After examining an equally intriguing rock named ‘Bright Angel’, Perseverance will take a month to scale the crater rim looking for more ancient material thrown up from the depths by the impact. The drill sample, named ‘Comet Geyser’, is the 24^th to be deposited by Perseverance for future collection (Fig. 4). Unfortunately the cost and timescale of the retrieval ($11 billion, for return to Earth by 2040) have both been judged unsatisfactory, and the whole Mars Sample Return is now under review.

Fig. 3. Drill and abrasion samples taken from ‘Bunsen Peak’ rock

Jupiter, Uranus and Neptune will all be too low and too close to the Sun to see from here. Uranus is at conjunction on the far side of the Sun on May 13^th, and Jupiter is at conjunction on the 18^th.

Jupiter’s volcanic moon Io continues to unveil dramatic images and results from its close flybys, within 930 miles, by the Juno spacecraft in December 2023 and February 2024. An image from February 3^rd shows the sub-Jovian hemisphere for the first time since the Voyager 1 flyby of March 1979 (Fig. 5). An image from the previous day shows the 200-km long Loki Patera, first imaged by Voyager 1 (Fig. 6) and later by Galileo in 1997 (Fig. 7), and the Juno image (Fig. 8) provides further evidence that it’s a lake of molten sulphur, fed by lava flows around its edge and with floating islands of sulphur on its surface (Fig. 9). A feature named ‘Steeple Mountain’, 5-7 km high with sheer sides, is also attracting attention. Juno performed a more distant pass of Io at 10,250 miles on April 4^th, and will complete its 61^st orbit of Jupiter on May 12^th. (Nancy Atkinson, ‘Juno Reveals a Giant Lava Lake on Io’, Universe Today, online, April 20^th 2024.)

Fig. 5. Jovian sub-hemisphere of Io within 930 miles, by sunlight reflected off Jupiter’s cloud tops, Feb 3, 2024,

Studies of the isotopic composition of Io’s sulphur have found that it’s more dense than average, due to differentiation in which lighter isotopes have diffused into space from the atmosphere after ejection from the moon’s volcanic plumes. The ratio suggests that Io has been volcanically active, in constant eruption driven by tidal interaction with Jupiter, since its formation 4.6 billion years ago. That too is remarkable because studies of exoplanets such as K2-18b have concluded that their entire surface may be molten due to heating from the same cause. The cosmonaut artist Andrei Sokolov produced a set of paintings showing human explorers showing such a planet which had evidently solidified, yet was still bright red (Fig. 10), perhaps because it orbited a red dwarf star or a red giant which had passed the peak of its expansion. The continuing presence of an atmosphere might suggest the latter, since it looks as if tidal action which keep most of Io molten for a long time to come.

Fig. 10. Andrei Sokolov, exoplanet of red giant or dwarf

Saturn, in Aquarius, is close to the waning Moon on the 4^th, when it’s occulted by it as seen from Australia and New Zealand, but it’s not likely to be seen from Scotland till the end of May, as above, when it will be near the Moon and rise about 3 a.m. (BST). As Saturn approaches its equinox the rings grow narrower, seen from Earth, and are now at an angle of only 2 degrees to us.

Pluto is in the news thanks to a new study at the University of Bern, of the western lobe of the heart-shaped feature named Sputnik Planitia (Fig. 11). The feature is bright because it’s a depression full of nitrogen ice, within which water icebergs travel along the cracks – suggesting hitherto that there may be liquid water below (Fig. 12), perhaps still liquid from the impact which formed the basin, possibly implying a water ocean surrounding the planet’s core (Fig. 13). But Pluto and its relatively large satellite Charon have mutually trapped rotations, and Sputnik Planitia is direct opposite the sub-Charon point, which should mean that its contents are more dense than their surroundings, rather than more. The new suggestion is that the bottom of the basin is a ‘mascon’, like those filled with dense lava on the Moon, but this one is the core of a rock impactor, 400 km in diameter, deposited in an oblique low-velocity impact (Fig. 14). Its nitrogen filling comes from ammonia released from the crust by the impact, and no sub-surface oceans in required – or if there is one, to explain the icebergs, it must be very shallow.

Fig. 11. Sputnik Planitia from New Horizons, 2015

The eta Aquarid meteors, one of the two showers from Halley’s Comet, will peak on the night of May 6^th, and although the shower will not be a strong one, with the comet just past its furthest distance from the Sun, there will be no Moon to mask the meteors that do appear.

Fig. 15. Event Horizon Telescope northern hemisphere sites

The Event Horizon Telescope (an international link-up that effectively generates a telescope the size of the Earth – Fig. 15) has obtained a new image of Sagittarius A*, the black hole at the centre of the Milky Way galaxy. The first black hole to be imaged in that way, in 2019, was the supermassive one in the galaxy M87, followed four years later by a polarised image showing the structure of magnetic fields around it. Sagittarius A* was first imaged in 2022, and although it’s much smaller than M87’s black hole (4.1 million times the mass of the Sun, as opposed to 6 billion times), the latest image shows that the polarisation is remarkably similar (Fig. 16). Sagittarius A* is so much smaller and closer to us that the pattern changes almost daily; what remains to be learned is whether all massive black holes have this pattern, or whether we happen to have captured ours when it momentarily looks like M87’s (‘News Update: Milky Way’s Black Hole Has a Magnetic Surprise’, Astronomy Now, May 2024).