Saturday, 21 October 2017

Wildfires kill 43 in Portugal.

Forty three people have been confirmed dead and a further 71 have been injured as a series of wildfires have swept across northern and central Portugal this week. The majority of those who have died have done so in their cars, trying to escape from raging forest fires on country roads. Over 600 separate fires have been reported, the second major outbreak of such fires this year, after a series of fires in June killed 64 people and injured over 250 more in the central Pedrogao Grande Region. At least four people have died in similar fires in neighbouring Spain this week.

 Forest fire in Portugal earlier this week. APTN.

The fires are reported to have a number of different causes, including in some cases deliberate arson, and have been made much worse by both a prolonged heatwave in Portugal. which has dried out vegetation making it vulnerable to fires, and high winds associated with Hurricane Ophelia which have fanned the blazes and helped them to spread rapidly. However the fires appear to have been worst not in areas of natural woodland, but in the countries extensive plantation forests (i.e. forests of planted trees grown for the value of their timber), with the most severe fires occurring in areas of Pine and, particularly, Eucalyptus cultivation.

Clouds of thick smoke from the forest fires above the town of Marinha Grande in the Leiria District of Portugal earlier this week. João Pinto/Severe Weather Europe.

Eucalyptus, or Gum Trees, are fast growing members of the Myrtle Family, Myrtaceae, native to Australia but now grown extensively for their timber in many other parts of the world. They are valued for their fast growth, enabling them to produce much timber quickly, However they dominate ecosystems in which they become established, causing a variety of problems both for native plants and animals, as Human residents. The trees produce large amounts of volatile terpanoids which suppress the growth of other plants, and consume large amounts of water, lowering the water table in areas where they become established. The trees also shed branches regularly, as well as leaves and strips of bark, creating a dry environment littered with dry plant material where wildfires quickly become established. The terpinoids in the wood of Eucalyptus cause these forests to burn readily, typically at a tempereature about 30 °C higher than other forest fires, which can kill specie such as Oak, which can often survive fires. This increases the ecological dominance of the Eucalyptus, as, while the trees are killed by the fires, the seed pods can survive and rapidly germinate after fires, which since the trees grow quickly, enables them to quickly claim the newly available land.

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Fireball over Long Island, New York.

The American Meteor Society has received reports of a bright fireball meteor being seen over Long Island, New York, at about 3.00 pm, Eastern Daylight Time (about 7.00 pm GMT), on Wednesday 18 October 2017. The majority of the sightings came from New York and New Jersey, though reports have come from Connecticut, Delaware, Rhode Island, Pennsylvania, Massachusetts, Maryland and New Hampshire as well. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. These are typically caused by pieces of rock burning up in the atmosphere, but can be the result of man-made space-junk burning up on re-entry.

The 18 October 2017 fireball meteor seen from Connecticut. News 12 Connecticut.

The meteor was seen to move from northwest to southeast, entering the atmosphere over Connecticut or Long Island and terminating over the Atlantic Ocean (such meteors typically terminate many kilometres above the Earth's surface in an explosion caused by friction with the Earth's atmosphere). 

The estimated trajectory of the 18 October 2017 fireball meteor. American Meteor Society.

Objects of this size probably enter the Earth's atmosphere several times a year, though unless they do so over populated areas they are unlikely to be noticed. They are officially described as fireballs if they produce a light brighter than the planet Venus. It is possible, though unlikely, that this object will have produced meteorites that reached the surface (an object visible in the sky is a meteor, a rock that falls from the sky and can be physically held and examined is a meteorite), though most meteorites come from larger objects that penetrate further into the atmosphere before exploding, and therefore have a better chance of producing fragments that reach the surface.

Witness reports can help astronomers to understand these events. If you witnessed this fireball you can report it to the American Meteor Society here.  

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Eurypeza aurora: A new species of Scarab Beetle from Nairobi, Kenya.

Scarab Beetles, Scarabeidae, are a large and diverse group, containing about 30 000 known species from around the world. These Beetles are typically large and robust, and often with a metallic colouration. Many Scarab Beetles are excellent diggers, and many of these digging Scarabs share a habit of burying their eggs with a supply of dung to feed their young, gaining them the name Dung Beetles, though others lay their eggs on carrion, decaying plant matter, or in some cases living plants.

In a paper published in the journal Zootaxa on 18 October 2017 Ruchard Sehnal of the Department of Zoology and Fisheries, at the Czech University of Life Sciences Prague, describe a new species of Scarab from Kenya.

The new species is placed in the genus Eurypeza, which currently contains a single species from Somalia, and given the specific name aurora:, meaning Morning Star. The species is described from a single male specimen collected from the town of Salama in the Nairobi Metropolitan Region. It is an elongate Scarab, about 9.6 mm in length, with a reddish-brown head and black body, though this is covered in yellowish white hairs giving it a brownish appearance.

Eurypeza aurora, male in dorsal view. Scale bar is 1 mm. Sehnal (2017).

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Bacterial infection kills 125 000 Salmon at Scottish Fish farms.

Around 125 000 Salmon have died following an outbreak of the Bacterium Pasteurella skyensis at two Fish farms in Loch Erisort on the island of Lewis in the Outer Hebrides, off the west coast of Scotland since August 2017. The outbreak has claimed the lives of about 500 tonnes of Fish at the Marine Harvest operated farms, prompting complaints from local residents about the scent of decaying Fish.

A Salmon farm on Loch Erisort. WDC.

Pasteurella skyensis is a is a Gram-negative, facultatively anaerobic (i.e. capable of using oxygen, but not needing it), non-motile, rod-shaped, Gammaproteobacteria, related to other pathogenic Bacteria such as Vibrio cholerae (Cholera), Yersinia pestis (Plague) and Esherchia coli (food poisoning), first described in 2002 from farmed Salmon in Scotland. Fish infected with the disease become lethargic and lose their apatite, and frequently die. The disease spreads rapidly in Salmon farms, where the Fish are kept at far higher density than they would occur at in nature. 

Other species of Pasteurella cause infections in Cattle, Sheep, Cats, Dogs, Horses, Rabbits, Chickens, Ferrets, Deer, Sealions, Pigs, Geese, Buffalo, Tortoises, and Humans. Many of these Bacteria are part of the natural flora of the mouths of a range of animals, including domestic Cats and Dogs. Most Pasteurella infections are associated with animal bites, and can be treated fairly easily, but others cause more serious problems including hemorrhagic fevers in some domestic animals and a form of Cholera in Birds.

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Thursday, 19 October 2017

Magnitude 4.8 Earthquake off the coast of Nicaragua.

The United States Geological Survey recorded a Magnitude  4.8 Earthquake at a depth of 76.5 km, about 25 km offshore of the Padre Ramos estuary on the coast of Chinandega Department, Nicaragua, slightly after 5.00 pm local time (slightly after 11.00 pm GMT) on Tuesday 17 October 2017. There are no reports of any damage or casualties associated with this event, though it was felt in Nicaragua and El Salvador.

 The approximate location of the 17 October 2017 Padre Ramos Earthquake. USGS.

Nicaragua is located on the southern part of the Caribbean Plate, close to its boundary with the Cocos Plate, which underlies part of the east Pacific. The Cocos Plate is being pushed northwards by expansion of the crust along the East Pacific Rise, and is subducted beneath the Caribbean Plate along the Middle American Trench, which runs parallel to the south coast of Central America, passing under the peninsula  as it sinks into the Earth's interior. This is not a smooth process, the plates tend to stick together, breaking apart again once the pressure from the northward movement of the Cocos Plate builds up to much, triggering Earthquakes. 

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

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Heavy rains bring flooding to south and central Trinidad.

Central and southern parts of the Caribbean island of Trinidad have suffered widespread flooding after a period of heavy rains and thunderstorms that lasted about 24 hours across Wednesday 18 and Thursday 19 October 2017. There are no reports of any casualties associated with this flooding, but transport networks have been severely disrupted and many homes inundated.

Flooding on Trinidad on Wednesday 18 October 2017. Loop.

Like other parts of the Caribbean, Trinidad has suffered a series of flooding events this summer, associated with a series of particularly severe hurricanes. However this weeks flooding is not associated with any hurricane, but rather appears to have been caused by the movement of the Inter-Tropical Convergence System, a permanent low pressure system that circles the globe approximately on the equator. 

This system is caused by heat from the Sun, which is greater at the equator then elsewhere, causing air over the equator to rise, and drawing in air currents from the Northern and Southern Hemispheres, forming the trade winds. This updraughts pull up water vapour from the sea surface high into the atmosphere, where it eventually precipitates out of the cooler, less dense atmosphere, falling back as rain. 

Flooding on Trinidad on Wednesday 18 October 2017. Loop.

Importantly, while the actual equator is fixed, the tilt of the Earth relative to the Sun means that the point at which the Sun is directly overhead moves northward in the northern summer and south in the southern summer, creating a thermal equator, which the Inter-Tropical Convergence System follows, moving north in the north and south with the seasons (and since  the sea heats and cools more slowly than the land, this movement is more pronounced over land than sea). The upshot of this is a system of storms which circulates on the equator at the equinoxes, but which moves north and south to the tropics around the solstices. Furthermore this system moves further away from the equator in warmer years, and is predicted as being likely to do so more with global warming. It is this  Inter-Tropical Convergence System which has passed over Trinidad this week, causing storms and flooding over the island.

The approximate position of the Inter-Tropical Convergence System in July and January.
Mats Halldin/

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Wednesday, 18 October 2017

Asteroid 2017 RV1 passes the Earth.

Asteroid 2017 RV1 passed by the Earth at a distance of about 6 820 000 km (17.7 times the average distance between the Earth and the Moon, or 4.58% of the distance between the Earth and the Sun), slightly before 4.45 am GMT on Thursday 12 October 2017. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2017 RV1 has an estimated equivalent diameter of 180-570 m (i.e. it is estimated that a spherical object with the same volume would be 180-570 m in diameter), and an object of this size would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be 12 000-600 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater over 2-8 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even centuries.

The calculated orbit of 2017 RV1. Minor Planet Center.

2017 RV1 was discovered on 12 September 2017 (thirty days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2017 RV1 implies that it was the 46th asteroid (asteroid V1) discovered in the first half of September 2017 (period 2017 R).

2017 RV1 has a 1377 day orbital period and an eccentric orbit tilted at an angle of 2.04° to the plane of the Solar System, which takes it from 0.89 AU from the Sun (i.e. 89% of he average distance at which the Earth orbits the Sun) to 3.94 AU from the Sun (i.e. 394% of the average distance at which the Earth orbits the Sun, considerably more than twice the distance at which the planet Mars orbits the Sun). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer). This means that the asteroid has occasional close encounters with the planet Earth, with the last thought to have occurred in September 2002 next predicted to occur in September 2036. It is also calculated to have occasional close encounters with the planet Jupiter, with the last thought to have happened in October 1970 and the next predicted for February 2031. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2017 SN2 is also classified as a Potentially Hazardous Asteroid (it comes no closer to the Sun than 105% of the average distance at which the Earth orbit's the Sun, but the Earth's orbit is not completely circular).

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