At least 148 dead amid flooding and landslides in Nepal.

At least 148 people have died and more than fifty are still missing in a series of flood and landslide events which hit Nepal driven by heavy rains which have fallen across the country since Friday 27 September 2024. The worst of the flooding has occurred in the densely populated Kathmandu Valley in the central part of the country, where 322 mm of rain fell within 24 hours between Friday and Saturday mornings, the largest amount of rain ever recorded within 24 hours in Nepal.

Flooding on the Bagmati River in Kathmandu on Saturday 28 September 2024. Anadolu Ajansi/Getty Images.

Thirty four people are known have died in Kathmandu, and at least 35 more in a series of landslides on the Prithvi Highway, outside the city, which buried two busses and several other vehicles. In the city Bhaktapur, 15 km to the east of Kathmandu, five people, including a pregnant woman and a four-year-old girl died when a house collapsed, and six people died when a landslide hit the All Nepal Football Association's training centre in Makwanpur. 

Flooding in Lalitpur, to the south of Kathmandu, on 28 September 2024. Gopen Rai/Nepal Times.

The annual monsoon in Nepal claims a large number of lives each year, with at least 170 known to have died this year between the onset of the monsoon season in June and the onset of Friday's rains. However, this rainfall typically ends towards the middle of September. This year's extended monsoon is thought to have been caused by a low pressure system over India, in turn caused by this year's exceptionally high global temperatures. Late rains such as these bring with them additional problems, as by September the ground in lowlying areas of Nepal is often waterlogged, and the waters rivers and lakes high, if not actually overflowing. This means that even if the rains stop soon, their effects are likely to be felt for some time yet, with the waters in the Koshi River recorded as running at a rate of over 12 700  cubic metres per second, compared to a seasonal average of 4200 cubic metres per second. Such high flow rates on the Koshi River almost invariably lead to significant flood events in Bihar State, India.

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Fossil pinnate Palm leaves from the Island Lagoon Flora, in the arid zone of South Australia.

Palms are an important part of the flora of the wet tropical and subtropical forests of eastern Australia, but are almost absent from the drier areas of the Australian interior, with only two species known from this area today, Livistona mariae from central Australia, and Livistona alfredii from the Pilbara region of Western Australia. Despite its large area, Australia is relatively species-poor in Palms compared with nearby landmasses, with only 54 species in 17 genera, compared to about 250 species on the island of New Guinea. 

The Palm flora of Australia contains a mixture of groups with different biogeographical regions, including Gondwanan groups, such as the Archontophoenicinae, Calamoideae, and Nypoideae, with fossil records in Australai which pre-date the Miocene, and Laurasian groups, such as Livistona spp., thought to have migrated from Southeast Asia since the Miocene, when monsoonal climates became prevalent across the region. Although of Gondwanan origin, the Archontophoenicinae are thought to have reached Australia from New Guinea in the Eocene, and subsequently dispersed from Australia to New Guinea in the Miocene. Beyond this, however, our understanding of the biogeographical origins of modern Australian Palms is severely limited by a paucity of fossils, particularly compared to the numerous fossil Palms of the Northern Hemisphere.

In a paper published in the journal Historical Biology on 25 September 2024, David Greenwood of the Department of Biology at Brandon University, and John Conran of rhe Environment Institute at the University of Adelaide, describe a new Palm species from fossil pinnate leaves from the Island Lagoon Flora for South Australia.

The Island Lagoon Flora is one of a number of ‘silcrete floras’ known the arid zone of South Australia, which produce a Plant fossils, which appear to have been species adapted to arid environments, with a smaller proportion of broad-leaved and Coniferous tree fossils. Age estimates for these floras have varied considerably since they were first recorded in the 1890s, with current estimates suggesting that different localities may reflect Eocene, Miocene, and Miocene-Pliocene assemblages. The Island Lagoon Flora is thought most likely to be of Miocene origin, probably contemporaneous with the Stuart Creek Silcrete Macroflora, though it is possible that it is older, possibly Eocene or Late Oligocene-Early Miocene.

The new Palm species is placed in the genus Phoenicites and given the specific name insula-lacuna, which is a Latin translation of 'Island Lagoon'. The species is described from two specimens, P14209 and P14467, both in the collection of the South Australian Museum. Both are incomplete portions of pinnate leaves, P14209 measuring 29.5 cm long and 27.7 cm wide, and P14467 measuring  23.9 cm long and 9.8 cm wide, with both showing at least 11 pinnae per side.

Phoenicites insula-lacuna. (A) Holotype P14209 showing whole specimen. (B) Paratype (P14467) with midvein at arrow. (C) Detail showing asymmetry of pinnae base (P14209). (D), (E) Detail of mid-pinnae showing midvein and secondary veins (P14209). (F) Rachis (P14209) showing patterned surface corresponding to ‘brown spots’ similar to those of extant Archontophoenix spp. (G) Detail of mid-pinnae with arrow showing midvein (P14467). John Conran in Greenwood & Conran (2024).

Greenwood and Conran note that there is little to differentiate the fossil genus Phoenicites from the living genus Archontophoenix, although they have chosen to use Phoenicites as the limited material available does not contain all of the diagnostic features for inclusion in the extant genus. This is a common situation in palaeontology, where all fossil species are morphospecies (species defined by their morphological appearance) rather than true biological species (which are defined by their ability to breed with other members of the species - something which fossils are incapable of doing).

(A)–(F) Extant Archontophoenix in the Adelaide Botanical Gardens and Waite Arboretum, University of Adelaide, or in habitat ((E) only). (A), (C) Archontophoenix alexandrae, whole leaf (A) and partial view of abaxial side (B) showing pinnae with prominent veins and pinnae rachis attachment. (B), (D) Archontophoenix cunninghamiana, partial view of abaxial side showing pinnae venation and rachis attachment, and (D) rachis showing brown spots that dry as ‘tuberculae’. (E) Archontophoenix purpurea and (F) Archontophoenix tuckerii showing pinnae venation and rachis attachment. John Conran and John Dowe in Greenwood & Conran (2024).

Modern members of the genus Archontophoenix are found in wet environments, such as freshwater swamps, rainforests, under monsoonal to seasonally dry climates. This is different from the drier climate generally recorded in the silcrete floras of South Australia. However, Greenwood and Conran note that one of the environments in which these Palms are found is rainforest gullies within (dry) tall Eucalypt forests, possibly providing a setting for the other more moisture-loving Plants found in these floras.

Map of Australia showing the Island Lagoon fossil locality, other South Australian Silcrete Flora sites, the arid zone (where the annual rainfall is less than 250 mm), the extant distribution of Archontophoenix (green circles) and the two extant species of Palm endemic in the arid zone (orange squares; Livistona alfredii in Western Australia and Livistona mariae in the Northern Territory).Abbreviations: NSW, New South Wales; NT, Northern Territory; Qld, Queensland; SA, South Australia; Tas, Tasmania; Vic, Victoria; WA, Western Australia. Greenwood & Conran (2024).

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Comet C/2023 A3 (Tsuchinshan-ATLAS) approaches perihelion.

Comet C/2023 A3 (Tsuchinshan-ATLAS) will reach perihelion (its closest approach to the Sun) on Friday 27 September 2024, when it will be 0.39 AU from the Sun (39% of the distance between the Earth of the Sun, slightly outside the orbit of the planet Mercury). At this distance the comet will be barely naked eye visible in the constellation of Sextans, having a magnitude about 3.9, but should be quite easy to distinguish with even a small telescope.

Comet C/2023 A3 (Tsuchinshan-ATLAS) on 16 June 2024. Composite image made up from seven 120 second exposures from the the Celestron 14"-F8/8.4 (356/3000 mm) Schmidt-Cassegrain Telescope at Ceccano in Italy. Gianluca Masi/Virtual Telescope Project.

C/2023 A3 (Tsuchinshan-ATLAS) was discovered on 9 January 2023 by the Purple Mountain Observatory in Jiangsu Province, China, on 9 January 2023, and independently by the Asteroid Terrestrial-impact Last Alert System (ATLAS) facility in Northern Cape Province, South Africa on 22 February of the same year. The name C/2023 A3 (Tsuchinshan-ATLAS) implies that the object is a comet 'C', that it was the third such object (3) discovered in the first half of January 2023 (period 2023 A) and that it was discovered by the Purple Mountain Observatory (Tsuchinshan is a transliteration of the Chinese 紫金山'', meaning Purple Mountain)  and the ATLAS system.

The trajectory of C/2023 A3 (Tsuchinshan-ATLAS), and its position on 27 September 2024. JPL Small Body Database.

Comet C/2023 A3 (Tsuchinshan-ATLAS) is a Parabolic Comet, which is to say a comet that was disrupted from an orbit in the Oort Cloud, and is passing through the Inner Solar System on a parabolic orbit that will probably not bring it back again. This parabolic trajectory is tilted at an angle of 139.11° to the plain of the Solar System.

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Sueviota aethon: A new species of Dwarf Gobi from the Red Sea coast of Saudi Arabia.

First described in 1988, the Dwarf Gobi genus Sueviota is distinguished from the closely related Eviota on the structure of its pelvic fins. The genus currently contains eight species, found from Papua New Guinea and the northwestern coast of Australia through to the Red Sea.

In a paper published in the journal ZooKeys on 12 September 2024, Viktor Nunes Peinemann and Lucía Pombo-Ayora of the Red Sea Research Center of King Abdullah University of Science and Technology, Luke Tornabene of the School of Aquatic and Fishery Sciences and Burke Museum of Natural History and Culture of the University of Washington, and Michael Berumen, also of the Red Sea Research Center of King Abdullah University of Science and Technology, describe a new species of Sueviota from the Red Sea coast of Saudi Arabia.

The new species is named Sueviota aethon, where 'aethon' derives from Aethon, one of the four Horses which drew the chariot of the Sun God Helios in Greek mythology; it is so named due to its similarity to the previously described Sueviota pyrios; Pyrios having been another of the four Horses. The species is described from ten specimens collected from exposed offshore reefs on the Saudi Arabian Red Sea coast, at depths of between 10 m and 30 m, although Nunes Peinemann et al. note that another specimen was observed at a depth of 53 m.

Holotype specimen of Sueviota aethon (UW 203365), shortly after being collected. Nunes Peinemann et al. (2024).

Specimens of Sueviota aethon are between 9.2 mm and 16.7 mm in length, and most known specimens are dark red in colour (one was a yellow-orange colour). The first dorsal fin is rounded-to-square in shape, with the second and third spines longer than the first. The rays of the second dorsal fin are commonly branched (at least some of these are branched in all known specimens). The body is covered by ctenoid (comb-edged) scales, but these are absent from the head and breast. Two rows of irregularly spaced conical teeth are present on both the lower and upper jaws. Both jaws also have enlarged canine teeth, with these forming part of the outer tooth-row in the upper jaw and the inner tooth-row in the lower jaw.

Micro-CT scan of Sueviota aethon (UW 203365, holotype) showing its osteological characters. (a) Close-up of head showing the enlarged canines on the upper jaw, (b) dentary, showcasing two enlarged canines in the internal row of teeth, (c) lateral view of the complete skeleton. Nunes Peinemann et al. (2024).

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The September Equinox.

The September Equinox falls on Sunday 22 September this year (2024), when the day and night will be of equal length in both of the Earth's hemispheres. The Earth spins on its axis at an angle to the plain of the Solar System. This means that the poles of the Earth do not remain at 90° to the Sun, but rather the northern pole is tilted towards the Sun for six months of the year (the northern summer), and the southern pole for the other six months (the southern summer). This means that twice a year neither pole is inclined towards the Sun, on days known as the equinoxes. 

Simplified diagram showing the tilt of the Earth throughout the year. Not to scale. The Human Adventures in Space Exploration.

The equinoxes fall each year in March and September, with the March Equinox being the Spring (or Vernal) Equinox in the Northern Hemisphere and the Autumn Equinox in the Southern Hemisphere, while the September Equinox is the Autumn Equinox in the Northern Hemisphere and the Spring Equinox in the Southern Hemisphere. On these two days the day and night are both exactly twelve hours long at every point on the planet, the only days on which this happens.

How the combination of the Earth's equatorial plane (horizontal circle labelled as Celestial equator) and the plane of the Earth's orbit (diagonal circle labelled as Path of the Sun) creates the Solstices and Equinoxes that we observe. Christopher Crockett.

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