Friday, 12 February 2016

Asteroid 2016 CG18 passes the Earth.

Asteroid 2016 CG18 passed by the Earth at a distance of 151 400 km (0.39 times the average distance between the Earth and the Moon, or 0.10% of the average distance between the Earth and the Sun; 131 400 km above the orbit at which the satellites supporting GPS systems operate), slightly at about 6.30 pm GMT on Saturday 6 February 2016. There was no danger of the asteroid hitting us, though had it done so it would have presented only a minor threat. 2016 CG18 has an estimated equivalent diameter of 3-12 m (i.e. it is estimated that a spherical object with the same volume would be 3-12  m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere more than 60 km above the ground, with only fragmentary material reaching the Earth's surface.

 The calculated orbit of  2016 CG18JPL Small Body Database.

2016 CG18 was discovered on 3 February 2016 (three days before its closest approach to the Earth) by the University of Arizona's Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. The designation 2016 CG18 implies that it was the 207th asteroid (asteroid G18) discovered in the first half of February 2016 (period 2016 C).

2016 CG18 has a 397 day orbital period and an eccentric orbit tilted at an angle of 5.04° to the plane of the Solar System, which takes it from 0.93 AU from the Sun (i.e. 93% of the average distance at which the Earth orbits the Sun) to 1.18 AU from the Sun (i.e. 118% of the average distance at which the Earth 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 close encounters between the asteroid and Earth are extremely common, with the last having occurred in July 2014 and the next predicted in February 2017. 

See also... unlikely to have killed man in Tamil Nadu.                                                          Indian newspaper The Hindu carried a report on Sunday 7 February 2016 in which the death of a man and injury of three other people as well as causing damage to several nearby buildings at the campus of a college in Vellore, Tamil Nadu, were described as... 2016 AK193 passes the Earth. Asteroid 2016 AK193  passed by the Earth at a distance of 9 157 000 km (23.8 times the average distance between the Earth and the Moon, or 6.12% of the average distance between the Earth and the Sun), slightly before 2.00 a m GMT on Saturday 30... (438661) 2008 EP6 passes the Earth.                                                         Asteroid (438661) 2008 EP6 passed by the Earth at a distance of 7 505 000 km (19.5 times the average distance between the Earth and the Moon, or 5.02% of the average distance between the Earth and the...

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Understanding the Tuli Mummy.

Mummified remains are extremely useful to archaeologists, as they can provide data on both the hard and soft tissues of long-dead individuals. Some ancient cultures, such as the Egyptians and Incas, produced numerous mummified burrials, but in other parts of the world such finds are rare, and generally associated with dry, desicating environments. In Southern Africa a number of such mummies have been reported from caves, rock shelters and other areas water has not been able to reach. The Tuli Mummy was discovered in October 2008 in a grave at the base of a cliff on the Northern Tuli Game Reserve in eastern Botswana. The mummy was wrapped in an cow hide, and was intitially thought to be the remains of an animal burried by poachers; it was therefore partially excavated before the true nature and importance of the find was realized.

In a paper publishd in the South African Journal of Science on 1 February 2016, Frank Rühli of the Institute of Evolutionary Medicine at the University of Zurich, Maryna Steyn of the Forensic Anthropology Research Centre at the University of Pretoria and the School of Anatomical Sciences at the University of the Witwatersrand, Morongwa Mosothwane of the Forensic Anthropology Research Centre at the University of Pretoria and the Archaeology Unit at the University of Botswana, Lena Öhrström, also of the Institute of Evolutionary Medicine at the University of Zurich, Molebogeng Bodiba, also of the Forensic Anthropology Research Centre at the University of Pretoria and Abigail Bouwman, again of the Institute of Evolutionary Medicine at the University of Zurich describe the results of a study of the Tuli Mummy, now housed in the Botswana National Museum, in which the mummy was examined in a CT scanner at the Bokamoso Private Hospital in Gaborone and had DNA extracted at the Archaeology Unit at the University of Botswana then analysed at the Institute of Evolutionary Medicine at the University of Zurich.

 The intact mummy, covered with animal skin, discovered in the Tuli region of Botswana. Rühli et al. (2016).

The Tuli Mummy is a male estimated to have been aged between 40 and 55 years, preserved with skin, nails and hair intact, though part of the right leg was missing, apparently due to scavenging by animals. The body was burried in a foetal possition, with arms and legs folded and the head inclined forwards. Radiocarbon dating of the remains yielded two possible date ranges, between 1675 and 1735 or between 1800 and after 1950, though examination of potshards found with the burrial suggest that the older range is more likely.

While the remains were handled under sterile conditions at the University of Botswana and Botswana National Museum, the initial part of the excavation was carried out under non-sterile conditions, which Rühli et al. acknowledge could be a source of potential contamination, however they hope that the cow hide in which the body was wrapped will have offered a measure of protection, and both bone and soft tissue was removed for DNA analysis.

Not all of the DNA recovered was of usable quality, much being degraded or of apparent bacterial origin, however it was possible to obtain a mitochondrial DNA (mtDNA) sequence, suitable for determining the haplogroup of the mummy (a haplogroup is a group of individuals shown to share a common acestry through the male or female line, using either mitochondrial or Y chromosome DNA). Because mitochondrial DNA is found in the mitochondria, organelles outside the cell nucleus, it is passed directly from mother to child without being sexually recombined each generation, enabling precise estimations of when individuals shared common ancestors, at least through the female line (it is also possible to trace direct ancestry through the male line, using DNA from the Y chromosome, which is passed directly from father to son without sexual recombination).

Analysis of mtDNA from the Tuli Mummy suggests it is a member of the L0 haplogroup, which is found in populations from Southern and East Africa today. The L0 haplogroup is divided into five main branches, thought to have shared a common femal ancestor who lived in East Africa between 150 000 and 170 000 years ago, though the quality of the sequence was not sufficient to assign the sample to any of these subgroups. Comparison of the sequence to other sequences on record showed comparison to a number of sequences donated by Southern Africans, notably a 87% match with a Kgalagadi individual, an 87% match with a Sotho individual, an 86% match with a Tswana and an 86% match with a Zulu (though it should be noted that the sequnce used was quite short.

CT scanning of the remains revealed several bones to be missing, notably the missing part of the right leg, as well as bones from both hands, also likely to have been the result of scavenging. The chest and abdomen of the body were heavly compressed, and the right leg out of position, though this is thought to have been caused after death, probably by animals scavenging the burrial. Several teeth were missing, possibly also having been lost after death. the remaining teeth were extremely worn down, possibly suggesting an older age at time of death than was originally thought, possibly in exess of 50 years.

(a) Three-dimensional volume rendering, (b) maximal intensity projection and (c) sagittal slice of the Tuli mummy. Arrows, soil/stones in cranial and thoracic cavity and pelvis; C, left calcaneal bone; LF, left femoral head; RF, right distal femur in reverse position. Rühli et al. (2016).

Rühli et al.could find no trace of the internal organs of the Tuli Mummy. This may represent a preservational artefact, though this would be hard to explain given the general good preservation of the body, or removal of the internal organs by scavenging animals, though this would be expected to result in far more extensive disruption of the skeleton than was observed. Alternatively the internal organs could have been removed deliberately prior to burrial in order to better preserve the body, as was the case in Ancient Egypt. Rühli et al. note that historical in Zimbabwe rulers deemed sacred were deliberately mummified before burrial, but slowly drying over a low fire, prior to wrapping the body in cloth or the hide of a bull and burried. The removal of internal organs during this process has not previously been recorded, but cannot be ruled out either, and would be consistent with a process of deliberate mummification. 

See also... a 500-year-old Inca child mummy.                                                         In recent years the development of methods for sequencing ancient DNA has led to a greater understanding of how many ancient peoples are related to modern populations, particularly in Europe. However the method has been little used in the Americas, and... the life history of the Egtved Girl.                                                              The ‘Egtved Girl’ was excavated near Egtved... of Leprosy in from an early Anglo Saxon grave from Essex, England.              Leprosy is caused by the Bacterium Mycobacterium leprae; it is fatal, incurable...

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Thursday, 11 February 2016

Meteorite unlikely to have killed man in Tamil Nadu.

Indian newspaper The Hindu carried a report on Sunday 7 February 2016 in which the death of a man and injury of three other people as well as causing damage to several nearby buildings at the campus of a college in Vellore, Tamil Nadu, were described as having been caused by a meteorite. This is in theory possible; large meteor imapcts are known to have caused considerable damage on the past, with airburst explosions such as the 2013 Chelyabinsk Meteor and 1908 Tunguska Bolide having caused damage and injuries (but no recorded deaths), while smaller objects have damaged homes and vehicles on numerous occasions and larger structures such as Meteor Crater in Arizona are attributed to prehistoric impacts. However experts in the field have questioned the likelyhood of this event being linked to a meteor impact for several reasons.

Police inspect the site of a suspected meteor impact in Vellore, Tamil Nadu, on Saturday 6 February 2016. The Hindu.

Firstly, in order for a meteor to impact the ground it must be derived from a parent body several meters across. Such small asteroids are now routinely searvhed for by a number of specialist sky-watching surveys looking for Near Earth Objects before they come close to the Earth, as well as other astronomical surveys that continuously observe the sky for other phenomena. Even if such bodies reaches the Earth undetected they will result in visible fireballs (meteors brighter than Venus) in the upper atmosphere as they explode due to friction induced heating high in the atmosphere, with any fragments reaching the ground several minutes later. Such Fireballs are typically observed by large numbers of people, and in the twenty first century seldom excape being recorded by CCTV, dashboard cameras and even people armed with camera phones, but there are no recordings or reported sightings of the 6 February 2016 Vellore incident.

Secondly pictures of an object described as the meteorite released by authoriies in Vellore are not suffiiently clear to enable clear identification. Meteorites (actual pieces of rock that fall to Earth, as opposed to meteors, which are shooting stars, bright lights in the sky caused by objects burning up in our atmosphere) have a distinctive surface patterna, caused by superheating as they pass through the atmosphere, which usually enables experts to identify them quickly, and even without this examination of the minerals will quickly enable their identifcation. No such images have emerged of the Vellore object, leading experts outside India to question its nature.

The only available image of the Vellore 'meteorite'. Tamil Nadu Police.

If the explosion was not cuased by a meteorite, then its actual nature remains to be identified. The most likely explanation is an explosion of strictly terrestrial nature, such as a malicious explosive device or malfunctioning piece of machinery. An a;ternative explanation would be a piece of debris falling from an aircraft. or possibly even a piece of space junk (part of a setellite in low Earth orbit or a discarded launch vehicle) that could fall to Earth without sufficient friction to cause a visible fireball (such a piece of space junk would accelerate towards the Earth under the influence of gravity, whereas asteroids have additional velocity from their own orbit around the Sun, meaning that they hit the atmosphere at far higher speeds).

See also... fireball over Saskatchewan and Manitoba.                                                   Many people have reported seeing a bright fireball over parts of southern Saskatchewan and Manitoba at about 8.40 pm local tine on Sunday 8 November 2015. A fireball is defined as a meteor (shooting star)... over northern Europe.           Eyewitnesses across much of northern Europe reported seeing a bright fireball in the sky moving southwest to northeast at about 6.05 pm GMT on Saturday 31 October 2015. The event was seen from the Netherlands, Germany, Denmark, southern...

When atoms join together to form molecules of more than two atoms they adopt fixed shapes, as the molecular bonds are held at set angles to...
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Truck swallowed by sinkhole in Kitchener, Ontario.

Two men travelling southbound on the Strasburg Road in Kitchener in southeast Ontario, at about 3.20 am local time on Wednesday 10 February 2016, had a close escape when their pickup truck drove into a submerged sinkhole about 2 m in depth. Both men were able to escape from the vehicle, though the truck was almost entirely submerged and had to be removed by a speialist recovery team later that morning after much of the water had been pumped away.

Vehicle trapped in a submerged sinkhole on the Strasburg Road in Kitchener, Ontario, on Wednesday 10 February 2015. Kevin Swayze/The Record.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace.

On this occasion the hole is believed to have been created by a burst water main which washed away soft sediments beneath the road, as well as causing a flood which hid the structural damage to the road. The burst main had been reported to Kitchener Utilities who already had a work team on site at the time of the incident, however this team had been unable to begin work due to traffic on the road, with vehicles fording the flood, and was waiting for Waterloo Regional Police to close the road when the incident occured.

See also... homes evacuated after giant sinkhole appears in South Amboy, New Jersey.      Three homes have been evacuated as a precautionary measure after a giant sinkhole opened up at South Amboy in Middlesex County, New Jersey, on Tuesday 24 March 2015. Residents were woken at about 6.00 am local time by noises that sounded like high winds... apartment block evacuated after sinkhole opens up.                                        An apartment block in the West Town area of Chicago, Illinois, has been evacuated after a sinkhole opened up next to it in the early... swallowed by sinkhole in Kane County, Illinois.                                                       Three people have been treated for injuries after a car fell into a sinkhole near Burlington in Kane County, Illinois, at about 4.00...
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Sunday, 7 February 2016

Eruption on Sakurajima volcano, Japan.

Sakurajima, an active volcano on Kyushu Island, Japan, underwent a spectacular eruption on Friday 5 February 2015, producing an ash column about 2.2 km in height as well as throwing incandescent material (glowing hot ash and/or rocks) several hundred meters from the crater. There are no reports of any damage or injuries following the event, but local authorities have placed a 2 km exclusion zone around the volcano as a precaution. 

An incandescent eruption on Sakurajima on 5 February 2016. ANP.

Sakurajima is one of Japan's most active volcano's with around 700 eruptions last year (the exact figure is hard to derive as eruptions often occur close together and may run into one another), though there have been no major events since September. This high level of activity is impressive, but prevents Sakurajima from becoming a major hazard, partly because people tend not to build homes or other structures too close to very active volcanoes, but also because the high levels of activity tend to prevent pressure within the volcano from building up to dangerous levels, which can lead to sudden very large and destructive eruptions on less obviously active volcanoes.

The location of the Sakurajima volcano. Google Maps.

Japan has a complex tectonic situation, with parts of the country on four different tectonic plates. Kyushu Island lies at the northeast end of the Ryukyu Island Arc, which sits on top of the boundary between the Eurasian and Philippine Plates. The Philippine Plate is being subducted beneath the Eurasian Plate, in the Ryukyo Trench, to the Southeast of the Islands. As it is drawn into the interior of the Earth, the tectonic plate is partially melted by the heat of the Earth's interior, and liquid magma rises up through the overlying Eurasian Plate to form the volcanos of the Ryukyu Islands and Kyushu.

 The movement of the Pacific and Philippine Plates beneath eastern Honshu. Laurent Jolivet/Institut des Sciences de la Terre d'Orléans/Sciences de la Terre et de l'Environnement.

See also... and pyroclastic flow on Sakurajima, Kyushu.                                             The Sakurajima Volcano, situated on an island in Kagoshima Bay, Kyushu, underwent a large explosive eruption on the morning of Friday 4 October 2013, producing a 4 km high ash column and triggering... city covered in ash by eruption on Sakurajima Volcano.                                      An eruption on Sakurajima Volcano, situated on an island in Kagoshima Bay, Kyushu, has coated the city of Kagoshima in a layer of ash. The eruption... on Sakurajima.                              On 9 August 2013 the Japan Meteorological Agency reported a 50 minute eruption on Sakurajima Volcano, which is one of Japan's most active and sits on an island in Kagoshima Bay, Kyushu Island, which produced a 3.5 km high ash column, as well...
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Twenty four confirmed deaths following Taiwan Earthquake.

Twenty four people have been confirmed dead and over five hundred have been injured with over a hundred more are still missing following an Earthquake in Taiwan that led to the collapse of a seventeen story residential building. The event happened slightly before 4.00 am local time on Saturday 6 February 2016 (slightly before 8.00 pm on Friday 5 February GMT), and was measured by the United States Geological Survey as having a magnitude of 6.7 and occurring at a depth of 10 km beneath the eastern part of the city of Tianan in the southern part of the country.

Rescue workers at the scene of the 6 February 2016 Tianan building collapse. Ashley Pon/Getty Images.

Taiwan has a complex tectonic setting, lying on the boundary between the Eurasian and Philippine Plates, with the Eurasian Plate being subducted beneath the Philippine Plate in the South and the Philippine Plate being subducted beneath the Eurasian in the East. Subduction is not a smooth process even in simple settings, with plates typically sticking together as pressure from tectonic expansion elsewhere builds up, then suddenly breaking apart and shifting abruptly, causing Earthquakes.

 The motion of the tectonic plates beneath Taiwan. The University of Memphis.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organization 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.
 The approximate location of the 6 February 2016 Tainan Earthquake. Google Maps.
See also... 4.7 Earthquake in central Taiwan. The Taiwan Central Weather Bureau reported a Magnitude 4.7 Earthquake at a depth of 7.4 km in the countries Central Mountain Range, slightly before 0.45 am local time on Wednesday 15 January 2014... least one person killed by Taiwan Earthquake.                                                    A Magnitude 6.2 Earthquake at a depth of about 20 km struck central Taiwan slightly before 1.45 pm local time (slightly before 5.45 am GMT) on Sunday 2 June... least one person dead following Magnitude 6.0 Earthquake in Taiwan.                          Central Taiwan was struck by a Magnitude 6.0 Earthquake at a depth of 20.7 km, slightly after 10.00 am local time (slightly after 2.00 am GMT) on Wednesday 27 March 2013, according to the...
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Three still missing following collapse at South African gold mine.

Three people are still missing following a collapse at the Vantage Goldfields operated Makonjwaan Lily Gold Mine near Low's Creek in Mpumalanga at about 8.40 am local time on Friday 5 February 2015. The incident was reportedly caused by the failure of an underground pillar, which in turn led to a roof collapse, trapping 87 miners below ground. All of these workers have now been rescued successfully with only miner injuries, however the collapse also led to the formation of a sinkhole (surface hole created by the formation of a void bellow ground)which swallowed a mobile office building in which two women and a man were working, It is these three mine employees, understood to have been involved in issuing miners with safety equipment, that are still missing and are still being actively sought by rescue teams. All production at the mine has ceased until further notice, and workers are being offered trauma counseling.

Friends and relatives of the missing mineworkers waiting for news at the Makonjwaan Lily Gold Mine. AP.

The Makonjawaan Lily Gold Mine is a shallow pit mine with an estimated reserve of about 0.35 million ounces of gold and an annual production of about 35 000 ounces per year. It accesses an ore body within the Barberton Greenstone Belt, an ancient (more than 3 billion years old) section of basement rocks underlying parts of South Africa and Swaziland, which forms the eastern part of the Kaapvaal Craton, one of the ancient blocks from which the continent of Africa was assembled. 

The approximate location of the Makonjwaan Lily Gold Mine.  Google Maps.

See also... miners rescued safely after fire at South African gold mine.                                            All the workers who were bellow ground at the Harmony Gold operated Kusasalethu Mine, at Carletonville near Johannesburg in South Africa, when an underground fire broke out on Sunday 22 February 2015 have... least one fatality following Magnitude 5.5 Earthquake in northern Free State, South Africa.                                                          The South African Council for Geoscience recorded... potential for geothermal energy in Limpopo Province, South Africa.                    South Africa is the largest producer of carbon dioxide on the African continent, and as such has committed itself to ambitious emission reduction plans, aiming to cut production of the gas by 40% by 2050. At the same...
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