Sunday, 22 July 2018

Asteroid 2018 NM passes the Earth.

Asteroid 2018 NM passed by the Earth at a distance of about 536 600 km (1.40 times the average  distance between the Earth and the Moon, or 0.36% of the distance between the Earth and the Sun), slightly before 5.30 am GMT on Tuesday 17 July 2018. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2018 NM has an estimated equivalent diameter of 9-31 m (i.e. it is estimated that a spherical object with the same volume would be 9-31 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 between 33 and 15 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2018 NM. Minor Planet Center.

2018 NM was discovered on 4 July 2018 (13 days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope. The designation 2018 NM implies that the asteroid was the 12th object (object M) discovered in the first half of Jul 2018 (period 2018 N).   

2019 NM has a 673 day orbital period and an eccentric orbit tilted at an angle of 1.73° to the plane of the Solar System, which takes it from 0.97 AU from the Sun (i.e. 97% of he average distance at which the Earth orbits the Sun) to 2.03 AU from the Sun (i.e. 203% of the average distance at which the Earth orbits the Sun, and further from the Sun than the planet Mars). 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 Earth, with the last thought to have occurred in June 2007.

See also...

https://sciencythoughts.blogspot.com/2018/07/asteroid-2018-nu-passes-earth.htmlhttp://sciencythoughts.blogspot.com/2018/07/fragment-of-asteroid-2018-la-found-in.html
http://sciencythoughts.blogspot.com/2018/07/asteroid-2018-nh-passes-earth.htmlhttp://sciencythoughts.blogspot.com/2018/07/asteroid-2018-mg7-passes-earth.html
https://sciencythoughts.blogspot.com/2018/06/fireball-over-southern-russia.htmlhttps://sciencythoughts.blogspot.com/2018/06/asteroid-2017-ye5-passes-earth.html
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Landslides kill four children in the Philippines.

Four children have been killed in two separate landslides in the Philippines over the past three days. On Friday 20 July 2018 a landslip in Agoo in La Union Province, on northern Luzon Island, crushed a house and burried it under more than a metre of mud, resulting in the deaths of John Jonard Galleros, 12, and his brother Joseph Galleros, 11. In a separate, but similar, incident early on Sunday 22 July, a second house was destroyed in Barbaza in Antique Province, on Panay Island in the Western Visayas group, resulting in the deaths of Rosalia Agapito, 6 and her brother Andrew Agapito, 3, as well as injuring their mother Tessie Agapito, 48.

The aftermath of a landslide that killed two children in Barbaza on Panay Island, the Philippines, on 22 July 2018. Johnny Juanites/Bong Erfe/GMA News.

The events are thought to have been triggered by high rainfall associated with Tropical Storm Josie, which swept past the Philippines this weekend, bringing with it high rainfall and widespread flooding, as well as a storm surge that resulted in thousands of people being evacuated from coastal areas on Luzon Island. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

Flooding in Pangasinan Province on Luzon Island. Pangasinan Provincial Disaster Risk Reduction and Management Council Rescue Operations.

Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm.

Floodwaters in Manila on Friday 20 July 2018. Bullit Marquez/AP.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.

See also...

https://sciencythoughts.blogspot.com/2018/06/magnitude-55-earthquake-off-coast-of.htmlhttps://sciencythoughts.blogspot.com/2018/02/saltwater-crocodile-kills-man-in.html
https://sciencythoughts.blogspot.com/2018/02/landslides-and-flooding-kill-five-as.htmlhttps://sciencythoughts.blogspot.com/2018/01/landslides-kill-six-in-philippines.html
https://sciencythoughts.blogspot.com/2018/01/evacuations-ordered-after-eruption-on.htmlhttps://sciencythoughts.blogspot.com/2017/12/flash-flood-destroys-village-on.html
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Saturday, 21 July 2018

Magnitude 1.1 Earthquake beneath Caernarfon Bay, North Wales.

The British Geological Survey recorded a Magnitude 1.1 Earthquake at a depth of about 12 km, beneath Caernarfon Bay on the coast of Gwynedd, North Wales, slightly before 11.00 pm British Summertime (slightly before 10.00 pm GMT) on Wednesday 18 July 2018. There are no reports of any damage or casualties associated with this event, and nor would they be expected with an Earthquake this small, but the quake was felt in Caernarfon, Talysarn, Llanfaelog and Cwm-y-glo.
 
The approximate location of the 18 July 2018 Caernarfon Bay Earthquake. Google Maps.
 
Earthquakes become more common as you travel north and west in Great Britain, with the west coast of Scotland being the most quake-prone part of the island and the northwest of Wales being more prone  to quakes than the rest of Wales or most of England.

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.

The precise cause of Earthquakes in the UK can be hard to determine; the country is not close to any obvious single cause of such activity such as a plate margin, but is subject to tectonic pressures from several different sources, with most quakes probably being the result of the interplay between these forces.
 
(Top) Simplified diagram showing principle of glacial rebound. Wikipedia. (Bottom) Map showing the rate of glacial rebound in various parts of the UK. Note that some parts of England and Wales show negative values, these areas are being pushed down slightly by uplift in Scotland, as the entire landmass is quite rigid and acts a bit like a see-saw. Climate North East.
 
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this quake, or were in the area but did not (which is also useful information) then you can report it to the British Geological Survey here. 

See also...

https://sciencythoughts.blogspot.com/2017/10/dozens-of-octopus-crawl-up-welsh-beach.htmlhttps://sciencythoughts.blogspot.com/2015/12/magnitude-15-earthquake-in-gwynedd.html
https://sciencythoughts.blogspot.com/2015/08/magnitude-12-earthquake-on-lleyn.htmlhttps://sciencythoughts.blogspot.com/2015/05/magnitude-30-earthquake-off-coast-of.html
https://sciencythoughts.blogspot.com/2014/12/two-rescued-from-disused-mine-in.htmlhttps://sciencythoughts.blogspot.com/2014/08/magnitude-10-earthquake-in-gwynedd.html
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Seventeen dead after pleasure boat sinks on Missouri lake during storm.

Seventeen people, including eleven members of one family, have died after a pleasure vessel sank on a Missouri lake on Table Rock Lake in Stone County, Missouri, on Thursday 19 July 2018. The vessel, described as an amphibous duck boat, reportedly got into trouble after a thundestorm struck, leading to a rapid deteriation of conditions. The victims are described as having been between 1 and 76 years in age.

A duck boat carrying tourists on Table Rock Lake in Missouri, shortly before sinking on 19 July 2018. Ron Folsom/Reuters.

Duck boats are amphiboius vehicles similar to those used in the Normandy landings during the Second World War. They are widely used as pleasure vehicles on inland waterways in parts of the US, but questions have been repeatedly raised about their suitability for such a role, as they do not cope well with rough weather conditions. The vehicle that sank on 19 July was reportedly carrying 31 people when it went down, and is known to have had life jackets on board, but it is unclear whether they were issued to passengers or whether passengers were waring them if they were. An investigation into the event is being led by the US Coastguard.

Thunderstorms are caused by heating of the land or water surface by the sun, causing air to expand, and thus rise, this causes more air to be drawn in to fill the gap, which is in turn heated and rises, repeating the process and creating a cycle. As the air rises it expands, and therefore cools, losing its capacity to retain water, leading to precipitation (rainfall), with higher levels of rainfall occurring when the initial air mass is warmer and more humid.

See also...

https://sciencythoughts.blogspot.com/2018/07/flash-flood-kills-radio-presenter-in.htmlhttps://sciencythoughts.blogspot.com/2018/06/train-derailment-leads-to-major-oil.html
https://sciencythoughts.blogspot.com/2018/06/arkansas-kayaker-killed-when-sinkhole.htmlhttps://sciencythoughts.blogspot.com/2018/04/oklahoma-man-killed-by-wildfire.html
https://sciencythoughts.blogspot.com/2018/04/tornado-injures-four-in-mountainburg.htmlhttps://sciencythoughts.blogspot.com/2017/09/iowa-woman-dies-from-west-nile-virus.html
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Poachers kill Ranger in Kruger National Park, South Africa.

A Park Ranger has been killed by suspected Rhinoceros poachers in the Kruger National Park, South Africa, according to South African National Parks. The incident occurred on Thursday 19 July 2018, when a Park Ranger patrol approached a group of suspected poachers, who opened fire on their vehicle. The dead Ranger was injured in the upper body during the attack and evacuated by air, but died before he reached hospital. The full identity of the Ranger has not yet been released, but he is described as having been male and from Bushbuckridge in Mpumalanga Province.

Rangers on patrol in the Kruger National Park, South Africa. Siyabona Africa.

Park authorities and private game reserves across Africa and Asia have been struggling with the problem of Rhino poaching for decades, but the problem has become more acute in recent years, with over a thousand killed in South Africa alone in 2017, and over 5500 in the past five years. The country is home to about 20 000 Rhinos, about 80% of the entire African population. The crime is extremely profitable, and widely believed to be controlled by organised crime syndicates, which are believed to have considerable influence over police and court officials in many areas, which results in suspected poachers often being released before they are brought to trial, often with only nominal bail payments.

See also...

https://sciencythoughts.blogspot.com/2018/07/lions-kill-at-least-three-poachers-in.htmlhttps://sciencythoughts.blogspot.com/2018/04/eleven-lions-poisoned-in-ugandan.html
https://sciencythoughts.blogspot.com/2018/04/poaching-in-kakum-conservation-area-of.htmlhttps://sciencythoughts.blogspot.com/2018/03/ceratotherium-simum-cottoni-last_20.html
https://sciencythoughts.blogspot.com/2018/03/ceratotherium-simum-cottoni-last.htmlhttps://sciencythoughts.blogspot.com/2018/02/vultures-and-lions-poisoned-outside.html
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Magnitude 5.0 Earthquake in Lower Silesia Province, Poland.

The United States Geological Survey recorded a Magnitude 5.0 Earthquake at a depth of 5.4 km, approximately 1 km to the northeast of the town of Polkowice in Lower Silesia Province, Poland, slightly after 5.30 am local time (slightly after 3.30 pm GMT) on Friday 20 July 2018. There are no reports of any damage or casualties associated with this event, but people have reported feeling it in Wawsaw.

The approximate location of the 20 July 2018 Lower Silesia Earthquake. USGS.

Poland is in northern Europe, an area not noted for its Earthquakes, but not completely immune either. Like other areas where Earthquakes are uncommon, it is seldom possible to give a precise cause for Polish Earthquakes, with both probably being the result of more than one source of tectonic pressure. The strongest source of tectonic stress in southern Poland is the impact of Africa with Europe, far to the south. This is causing uplift and folding in the Alpine region of Central Europe, and exert pressure on the rocks further to the north. There are also areas of minor tectonic spreading beneath the Rhine Valley and North Sea, both of which cause stress over a wide area. Finally there is glacial rebound; until about 10 000 years ago much of northern and upland Europe was covered by a thick layer of glacial ice, pushing the rocks of the lithosphere down into the underlying mantle. This ice is now gone, and the rocks are slowly springing back into place, causing occasional Earthquakes in the process.

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.

See also...

https://sciencythoughts.blogspot.com/2017/11/seven-dead-as-north-sea-storm-herwart.htmlhttps://sciencythoughts.blogspot.com/2017/08/poland-storms-kill-five.html
https://sciencythoughts.blogspot.com/2016/09/cave-in-at-polish-copper-mine-kills-two.htmlhttps://sciencythoughts.blogspot.com/2013/12/at-least-twelve-dead-as-cyclone-bodil.html
https://sciencythoughts.blogspot.com/2013/03/polish-miners-rescued-after-earthquake.htmlhttps://sciencythoughts.blogspot.com/2012/04/southwest-poland-hit-by-earthquake.html
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Total lunar eclipse to be visible from East Africa and South Asia.

A total Lunar Eclipse will occur on Friday 27 July 2018, starting slightly before 5.13 pm am GMT. It will be visible across much of Southern, Central and East Africa, as well as South and Southwest Asia, Antarctica, and the Islands of the Indian Ocean. Part of the eclipse will be visible from remaining areas of Asia and Africa as well as Europe, Australia, South America, the islands of the Atlantic, west Pacific, and east Caribbean, although in these areas the Moon will either rise part way through the eclipse, or set before it is complete.

 Areas from which the 27 July 2018 Lunar Eclipse will be visible. In the white area the full extent of the eclipse will be visible, in the shaded areas it will either begin before the Moon rises or end after the Moon has set, while in the darkest area it will not be visible at all. HM Nautical Almanac Office.

The Moon produces no light of its own, but 'shines' with reflected light from the Sun. Thus at Full Moon the Moon is on the opposite side of the Earth to the Sun, and its illuminated side is turned towards us, but at New Moon the Moon is between the Earth and the Sun, so that its illuminated side is turned away from us.

 How the phases of the Moon are caused by the relative positions of the Earth, Sun and Moon. Karl Tate/Space.com.

Lunar eclipses occur when the Moon passes through the Earth's shadow. This can only happen at Full Moon (unlike Solar Eclipses, which happen only when the Moon passes between the Earth and the Sum, and therefore only occur at New Moon), but does not happen every Lunar Month as the Sun, Moon and Earth are not in a perfect, unwavering line, but rather both the Earth and the Moon wobble slightly as they orbit their parent bodies, rising above and sinking bellow the plane of the ecliptic (the plane upon which they would all be in line every month). 

 Phases of the Lunar Eclipse that will be seen on 27 July 2018. The times are given in GMT, to the nearest 10th of a minute, thus 23.30.3 represents 18 seconds after 11.30 pm GMT. HM Nautical Almanac Office.

See also...

https://sciencythoughts.blogspot.com/2018/02/partial-solar-eclipse-to-be-visible.html
https://sciencythoughts.blogspot.com/2018/07/partial-solar-elipse-to-be-visible-from.html

https://sciencythoughts.blogspot.com/2017/12/furthest-lunar-apogee-of-2017.html
https://sciencythoughts.blogspot.com/2018/01/total-lunar-eclipse-on-31-january-2018.html
https://sciencythoughts.blogspot.com/2017/08/partial-lunar-eclipse-7-august-2017.html
https://sciencythoughts.blogspot.com/2017/08/total-solar-eclipse-to-be-visible-from.html


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