The Ursid Meteor Shower.

The Ursid Meteors are expected to peak at about 10 pm GMT on the evening of Sunday 22 December this year, with the shower being potentially visible to some extent between Sunday 17 and Monday 26 December.  The shower is typically best seen between midnight and dawn from anywhere in the Northern Hemisphere (it is difficult,if not impossible, to view it from the Southern Hemisphere). The extent of the shower is variable, some years producing over 100 meteors per hour at its peak, others less than 10. The peak of this years shower coicides with the Third Quarter Moon, also on 22 December, so viewing may be somewhat impaired, as glare from the Moon can hinder the viewing of meteors. The meteor shower gets its name from the constellation of Ursa Minor, in which it appears to originate.

The radiant (apparent point of origin) of the Ursid Meteors. BBC Science Focus Magazine/PA.

Meteor streams are thought to come from dust shed by comets as they come close to the Sun and their icy surfaces begin to evaporate away. Although the dust is separated from the comet, it continues to orbit the Sun on roughly the same orbital path, creating a visible meteor shower when the Earth crosses that path, and flecks of dust burn in the upper atmosphere, due to friction with the atmosphere.

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob.

The Ursid Meteor Shower is caused by the Earth passing through the tail of Comet 8P/Tuttle, and encountering dust from the tail of this comet. The dust particles strike the atmosphere at speeds of over 200 000 km per hour, burning up in the upper atmosphere and producing a light show in the process. The Earth does not need to pass close to Comet 8P/Tuttle for the meteor shower to occur, it simply passes through a trail of dust from the comet's tail that is following the same orbital path. Comet 8P/Tuttle visits the Inner Solar System once every 13.6 years, last doing so in 2021.

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

Comet 8P/Tuttle was discovered by Horace Parnell Tuttle on 5 January 1858. The designation 8P/Tuttle indicates that it was the eighth comet discovered (people have known about comets for thousands of years, but it was only realised that they were objects orbiting the Sun, which could be repeatedly observed and predicted, in the mid-eighteenth century), that it is a Periodic Comet (comet with an orbital period of less than 200 years) and that it was discovered by Horace Parnell Tuttle.

Comet 8P/Tuttle imaged from Weißenkirchen in der Wachau in Austria on 30 December 2007. Michael Jäger/Spaceweather.

Comet 8P/Tuttle has an orbital period of 4972 days (13.6 years) and a highly eccentric orbit tilted at an angle of 55.0° to the plain of the Solar System, that brings it from 1.03 AU from the Sun at closest perihelion (103% of the distance between the Earth and the Sun) to 10.4 AU from the Sun at aphelion (10.4 times as far from the Sun as the Earth or slightly outside the orbit of the planet Saturn). As a comet with a period of less than 20 years, 8P/Tuttle is considered to be a Jupiter Family Comet.

The calculated orbit and position on 21 December 2024 of 8P/Tuttle.  JPL Small Body Database.

This means that 8P/Tuttle has occasional close encounters with the Earth, with the last thought to have happened in January 2008 and the next predicted in December 2048. The comet also has occasional close encounters with the planets Jupiter, which it last came close to in December 1995 and is next predicted to pass in September 2078, and Saturn, which it last came close to in February 1930 and is expected to pass again in February 2107. Objects which make close passes to multiple planets are considered to be in unstable orbits, and are often eventually knocked out of these orbits by these encounters, either being knocked onto a new, more stable orbit, dropped into the Sun, knocked out of the Solar System or occasionally colliding with a planet. 

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Magnitude 7.3 Earthquake to the west of Efate Island, Vanuatu.

The United States Geological Survey recorded a Magnitude 7.3 Earthquake at a depth of 57.1 km, roughly 30 km to the west of of Efate Island, Vanuatu, slightly after 12.45 pm local time (slightly after 1.45 am) on Tuesday 17 December 2024. The initial event has been followed by a number of large aftershocks. At least fourteen people are known to have died as a result of the Earthquake, with more than 200 more injured. Many buildings, including hospitals on the island have been damaged, as have several important bridges, and seeveral major roads are reported to have been blocked by landslides.

The approximate location of the 17 December 2024 Vanuatu Earthquake. USGS.

Vanuatu is located on the southwestern fringe of the Pacific Plate, close to its boundary with the Australian Plate, which is being subducted along the New Hebrides Trench, to the west of the islands. The subducting Australian Plate passes under the islands of Vanuatu as it sinks into the Earth, causing Earthquakes as the plates stick together then break apart as the pressure builds up. As the plate sinks further it is partially melted by the heat of the friction combined with that of the Earth's interior. Some of the melted material then rises through the overlying Pacific Plate, fuelling the volcanoes of Vanuatu.

Damage to a building in Port Vila, Vanuatu. Tim Cutler/AP.

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The December Solstice.

The December (or Southern) Solstice this year falls on Saturday 21 December this year, with the Sun reaching its southernmost point in the sky at 9.20 am GMT. This is the shortest day of the year in the Northern Hemisphere, where it is known as the Winter Solstice and the longest day in the Southern Hemisphere, where it is known as the Summer Solstice. At very high latitudes the sun may not rise (Northern Hemisphere) or set (Southern Hemisphere) for several weeks on either side of the Southern Solstice.

The solstices are entirely a product of variation in the Earth's rotation on its axis, which is at an angle of 23.5° to the plain of the Earth's orbit about the Sun. This means that in December the Earth's Southern Pole is tilted towards the Sun, while the Northern Pole is tilted away from it. This means that around the Southern Solstice the Southern Hemisphere is receiving radiation from the Sun over a longer part of the than the Northern, and at a steeper angle (so that it to pass through less atmosphere to reach the planet), creating the southern summer and northern winter.

The tilt of the Earth during the December Solstice. Wikimedia Commons.

The solstices are fairly noticeable astronomical events, and tied to the seasons which govern the life cycles of life on Earth, and they have been celebrated under different names by cultures across the globe, but most notably by those at higher latitudes, who are more profoundly affected by the changes of the seasons.

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Florissantia sp.: A fossil flower from the Early Eocene of Rajasthan.

The Malvaceae first appeared in the Cretaceous in North America, and have achieved a global distribution today, most notably as a significant component of almost all tropical forests. The genus Florissantia shows a number of features associated with different extant subfamilies of the Malvaceae, and is known from the Middle Eocene till the Miocene of western North America, with specimens known from British Colombia, Colorado, Montana, Oregon, and Washington, as well as a single specimen being known from the Sikhote Alin mountains of the Russian Far East.

In a paper published in the journal Botany Letters on 21 October 2024, Ashif Ali and Mahasin Ali Khan of the Palaeobotany, Palynology, and Plant Evolution Laboratory at Sidho-Kanho-Birsha University, and Raman Patel and Rajendra Singh Rana of the Department of Geology at Rauthan Hemvati Nandan Bahuguna Garhwal University, describe a specimen of Florissantia from the Early Eocene Palana Formation of Rajasthan, India.

The specimen comes from the Laminate Maroon Shale Bed of the Palana Formation, which is exposed at the Gurha Open-cast Lignite Mine at Bikaner in northwest Rajasthan. It is preserved as part and counterpart on a piece of a piece of split- laminated shale, which has been further exposed by micro excavation of successive layers of the rock with fine needles under a dissection microscope. 

(a) Map of Rajasthan showing the location of the Gurha opencast lignite mine (red star) Bikaner Rajasthan, India; (b) view of the fossil locality. Ali et al. (2024).

The preserved fossil is a star-shaped flower about 13 mm in diameter (sgnificantly smaller than any other member of the genus), with a calyx made up of five fused and rounded sepals of roughly equal length; the petals are missing. Importantly, the sepals each show numerous prominent veins, the pattern of which is used by Ali et al. as a diagnostic tool to place the specimen in the genus Florissantia.

(a) Transversely impressed, radially symmetric, pentamerous fossil flower of Florissantia sp. (SKBU/PPL/R/F/01A, part); (b) magnified image of the specimen showing thick filaments (marked by red arrows) surrounding the compressed, carbonaceous central area; (c) enlarged view of a single calyx lobe showing prominent parallel (marked by blue arrows) and radiating reticulate (marked by white arrows) venation; (d) counterpart of fossil flower of Florissantia sp. (SKBU/PPL/R/F/01B); (e) central area of figured in higher magnification; (f) line drawing of (c) showing parallel (marked by blue arrows) and reticulate (marked by red arrows) venation, Scale bars are 2.5 mm for (a), (b), (d), and (e) and 500 μm for (c) and (f). Ali et al. (2024).

The Palana Formation of Rajasthan has been dated to between about 55 and 52 million years before the present on the basis of palynological data (fossil pollen). This Early Eocene date makes the Bikanar specimen the oldest representative of the genus Florissantia, which together with its unexpected location, potentially makes the specimen highly significant. 

Line drawings of the Bikanar specimen and earlier reported extinct fossil flower species: (a) Bikanar fossil flower of Florissantia sp.; (b )fossil flower of Florissantia ashwillii from the Oligocene of Oregon; (c) fossil flower of Chaneya membranosa from the Miocene of Poland; this appears similar to Florissantia spp, but has unequal sepals. Scale bars are 5 mm. Ali et al. (2024).

The Palana Formation was laid down on the shores of an ancient lake, which is consistent with other locations where members of the genus Florissantia have been found. Other members of the genus are known from lake-associated Floras in tropical, subtropical, and temperate environments, often with some volcanic input; although the presence of volcanic ashes helps to preserve fine structures such as flowers, so it is possible that this connection with volcanic input reflects preservation bias rather than an environmental preference of the living plants.

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Unknown disease kills 31 people in the Democratic Republic of Congo.

Between 24 October and as of 5 December 2024, 406 cases of an unknown disease were reported in the Panzi Health Zone of Kwango Province in the Democratic Republic of Congo, with 31 known fatalities, a case fatality ratio of 7.6%. Symptoms of the disease include fever, headache, cough, runny nose, and body ache, according to a press release issued by the World Health Organization on 8 December 2024. The number of both cases and deaths is likely to be higher than the official figure, with the Ministry of Health of the Democratic Republic reporting that they are aware of deaths within the local community of people who have not visited health facilities.

The approximate location of the Panzi Health Zone. Google Maps.

Cases of the unknown disease have been reported in nine of the thirty health areas which make up Panzi Health Zone, Kahumbulu, Kambandambi, Kanzangi, Kasanji, Kiama, Mbanza Kipungu, Makitapanzi, Mwini ngulu, and Tsakala Panzi, with the majority of the cases in Tsakala Panzi (169 cases), Makitapanzi (142 cases) and Kanzangi (78 cases).

Children under five years old account for 53% of cases and 54.8% of the deaths, with 64.3% of the cases and 71% of deaths occurring in children under 15. One hundred and forty five cases, including nine fatalities, have been  reported in adults.  Women and girls make up 59.9% of the cases, and the majority of deaths have occured in villages. 

Panzi Health Zone has a low vaccine uptake rate, poor food security, transport networks are poor (it takes about two days to reach Kinshasa by road in the rainy season). There are few trained health workers in the region, with very little care management and almost no access to diagnostic services.

Malaria is endemic to the region, with few control measures in place, as are a number of other potentially fatal diseases, including measles, influenza, respiratory tract infections, E. coli, and Covid-19. The high rate of food insecurity in the region means that malnutrition may be a contributing factor towards fatalities.

The lack of systematic medical recording in Panzi Health Zone means that although an increase in cases of fever, coughs, headaches, and body aches have been noted since October, it is unclear what the baseline rates for these symptoms are. Nor are there accurate records of vaccination schemes in the area, making it unclear to what extent the outbreak relates to vaccine deprivation. Many cases of the illness have been reported in family clusters, potentially suggesting transmission within households.

The area where the outbreak is occurring is very remote, with poor roads, limited mobile phone and internet coverage, and frequent shortages of even basic medication. There is no functional diagnostic laboratory in Kwango Province, requiring samples to be shipped to Kinshasa for analysis, a journey of two days by road in the rainy season. This process is further hampered by a lack of a formal sampling procedure in the region, and a poor security situation, with a number of armed groups operating in the area.

The remote  locality of the outbreak may make it harder for the disease to spread to other areas, but with no effective monitoring or diagnostic program in place there is little way to be sure. In addition, the area of the outbreak is close to the border with Angola, creating a potential for the disease to spread across the border.

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