Sunday, 31 August 2014

The Alpha Aurigid Meteors.

The Alpha Aurigid Meteor shower occurs each year between 25 August and 6 September, peaking between 11.30 pm GMT on 31 August and 0.30 am GMT on 1 September. However the shower is notoriously hard to observe, having been recorded only in the years 1911, 1929, 1930, 1935, 1979, 1980, 1986, 1994 and 2007 (some of these observations occurred before the 'official' discovery of the shower by Cuno Hoffmeister and Artur Teichgraeber in 1935, but have subsequently been linked to the shower), though the shower occurs between the New and First Quarter Moons this year, so it may be possible to observe it. The shower has its radiant (the point from which the meteors appear to radiate) in the constellation of Auriga.

The radiant of the Alpha Aurigid Meteors. Copper Mountain Mesa.

Meteor showers occur when the Earth crosses the orbit of a comet or similar body, encountering millions of tiny particles left behind in that body's trail, even if it is not close by itself. The Alpha Aurigid Metoers are thought to originate from the tail of the comet C/1911 N1 (Kiess). This is a Long Period Comet (comet with a period of longer than 200 years), thought to visit the inner Solar System only once every 2497 years, last having done so in August 2011, when it came to about 0.2 AU from the Earth (i.e. about 20% of the distance between the Earth and the Sun). The orbit of C/1911 N1 (Kiess) is highly elliptical, and tilted at an angle of 148° to the plane of the Solar System (or 58° with a retrograde orbit - an orbit in the opposite direction to the planets) and takes the comet from 0.68 AU from the Sun (68% of the average distance between the Earth and the Sun, slightly inside the orbit of Venus) to 367 AU from the Sun (367 times as far from the Sun as the Earth, or 20 times as far as Neptune, but within the inner part of the Oort Cloud).

The orbit and current position of comet C/1911 N1 (Kiess). JPL Small Body Database Browser.

See also...


The Perseid Meteor shower lasts from late July to early September each year, and are expected to be at a peak on 12-13 August 2014, slightly after the Full Moon on 10 August, which may make the meteors harder to spot...



The Eta Aquarid Meteor Shower will be at a peak on Monday 5/Tuesday 6 May 2014, with up to 45 meteors per hour at it's peak, radiating from the constellation of Aquarius. This does not spend long above the horizon in...




The Ursid Meteors are expected to peak on 22 December this year, with the shower being potentially visible to some extent between 17 and 26 December. The extent of the shower is variable, some years...



Follow Sciency Thoughts on Facebook.

Saturday, 30 August 2014

Eruptions on Mount Tavurvur.

Mount Tavurvur, an active stratovolcano (cone-shaped volcano) on the eastern part of the Rabul Caldera on the Island of New Britain, part of Papua New Guinea, underwent a major eruption on Friday 29 August 2014, producing a n ash column which rose 18 000 m above the mountain's summit, according to the Darwin Volcanic Ash Advisory Centre. The volcano continued to erupt through Saturday 30 August, with hot ash and chunks of rock being thrown several hundred meters from it's crater, but has shown no signs of a repeat of Friday's event, and activity appears to be subsiding.

Ash column over Mount Tavurvur on Friday 29 August 2014. AFP.

The Rabaul Caldera lies at the northern end of the island of New Britain, forming a peninsula and natural harbour, with the town of Rabaul on its northern rim. Unfortunately the caldera also has a number of active volcanoes of around its rim, which have led to serious problems for the town over its history, most notably in 1937 and 1994, when simultaneous eruptions from two volcanoes (Tavurvur and Vulcan) killed 507 and 5 people respectively. The town has been partially evacuated as a result of Friday's eruption.

The Rabaul Caldera. USGS.

New Britain lies on the boundary between the South Bismarck and Solomon Sea tectonic plates. The Solomon Sea Plate is being subducted beneath the South Bismarck Plate, which causes friction as the plates rub together, occasionally leading to Earthquakes. As the Solomon Sea Plate sinks into the Earth it is melted by the heat of the planets interior. Some of the melted material then rises through the overlying South Bismarck Plate, fueling the volcanoes of New Britain.

The subduction of the Solomon Sea Plate beneath New Britain. Oregon State University.

See also...


A Magnitude 6.5 at a depth of 63 km occurred beneath the interior of western New Britain Island, Papua New...


Mount Langila is an active complex volcano comprised of four overlapping craters emerging from the northeast flank of the extinct Talawe Volcano on Cape Gloucester at the western tip of New Britain, Papua New Guinea...



On Sunday 29 July 2012, slightly after 6.00 am local time (slightly after 8.00 pm on Saturday 28 July, GMT) the Papuan islands of New Ireland and New Britain were shaken by an Earthquake 20 km east of the southern coast of New Ireland, recorded by the United States Geological Survey as measuring 6.6 on the Richter... 



Follow Sciency Thoughts on Facebook.

Two new species of viviparous Halfbeaks from Sulawesi.

Halfbeaks (Zenarchopteridae) are small freshwater, estuarine and fully marine Bony Fish related to Needlefish and Flying FIsh. They are found across the Indo-Pacific Region, distinctive for their elongate lower jaws, which extend some way forward of the mouth. Members of the viviparous (live-young bearing) genus Nomorhamphus are found in hill streams and lakes on Sulawesi and the Philippines.

In a paper published in the Raffles Bulletin of Zoology on 9 May 2014, Jan Huylebrouck of the Zoologisches Forschungsmuseum Alexander Koenig, Renny Kurnia Hadiaty of the Museum Zoologicum Bogoriense and Ichthyology Laboratory at the Research Center for Biology of the Indonesian Institute of Sciences, and Fabian Herder, also of the Zoologisches Forschungsmuseum Alexander Koenig, describe two new species of viviparous Halfbeaks from Sulawesi.

The first new species described is named Nomorhamphus lanceolatus, meaning ‘lance-shaped’, a reference to the shape of the spiculus (a bone in the anal fin). Nomorhamphus lanceolatus is a yellowish-brown Halfbeak with a black spot on its pectoral fin. It’s lower jaw is short for a Halfbeak (confusingly making the Fish less lance-shaped than most of its relatives), and it reaches about 50 mm in length.

Nomorhamphus lanceolatus; Indonesia, Sulawesi: Sulawesi Tenggara; Wawolambo River, near the bridge on the road, between Kolaka and Kendari, 04°02'51.6"S 121°42'40.8"E. (A) male; (B) female. Renny Kurnia Hadiaty in Huylebrouck et al. (2014).

Nomorhamphus lanceolatus was found living in the Wawolambo River in the Sampara river basin, near a bridge on the Kolaka-Kendari road. The river was shaded by trees in the area where the Fish were collected, and about 7-9m wide and 50 cm deep.

The second new species described is named Nomorhamphus sagittarius, meaning ‘archer’ in reference to the shape of the Fish, which resembles an arrow. Nomorhamphus sagittarius is black in colour, with yellowish-orange fins reaching about 65 mm in length, with a strongly elongate lower jaw.

Nomorhamphus sagittarius; Indonesia, Sulawesi: Sulawesi Tenggara; Mangolo River, 03°58'56.6"S 121°34'05.5"E. (A) Male; (B) male, immediately after catching. Renny Kurnia Hadiaty in Huylebrouck et al. (2014).

Nomorhamphus sagittarius was found at two sites in the Sungai Mangolo (River Mangolo) and one site each in two of its tributaries, the Tawo-Tawo and Watumbasi. At the first Sungai Mangolo site the river was 6-8 m wide and 10-100 cm deep, with clear water and a sand and rock riverbed. At the second site the river was 5-7 m wide and 10-50 cm deep, with a rocky bed, overhung by the forest canopy and with water made murky by the activities of gold miners. At the Sungai Tawo-Tawo site the river is 3-5 m with and 10-50 cm deep, with clear water and a sand and gravel river bed, and much vegetation in the river. At the Sungai Watumbasi site the river is 1-3 m wide and 10-30 cm deep with a mud and sand bottom.

Mangolo River, first locality for Nomorhamphus sagittarius. Renny Kurnia Hadiaty in Huylebrouck et al. (2014).

See also…

 A new species of River Loach from Rakhine State, Myanmar.

River Loaches (Nemacheilidae) are ubiquitous members of the Eurasian freshwater fauna, with at least...

 Two new species of Gourami from Sumatra.

Gourami (Osphronemidae) are freshwater members of the Perch Order (Perciformes) found from Pakistan to Korea and south to Indonesia. They are often found in shallow, warm, oxygen-poor waters, and have a special...


 A new species of tree-dwelling Fighting Fish from Thailand.

Fighting Fish (Bettas) are colourful members of the Gourami Family (Osphronemidae) popular in the...


Follow Sciency Thoughts on Facebook.

Friday, 29 August 2014

Neptune at opposition.

The planet Neptune reached opposition (i.e. was directly opposite the Sun seen from Earth) at  2.18 pm GMT on Friday 29 August 2014. This means that it will both be at its closest to the Earth this year, about 28.96 AU (28.96 times the average distance between the Earth and the Sun, or about 4 332 000 000 km), and completely illuminated by the Sun. While it is not visible to the naked eye observer, the planets have phases just like those of the Moon; being further from the Sun than the Earth, Neptune is 'full' when directly opposite the Sun. 

The planet Neptune, as imaged by the Voyager 2 space probe. NASA.

While the relative positions of the planets have no direct influence on life on Earth, the opposition of Saturn does present the best opportunity for observations of the planet by Earth-based observers. At the moment Neptune is well placed for observation in the constellation of Aquarius, and while not naked-eye visible it should be possible to observe the planet through a moderate sized telescope.

See also...


The dwarf planet Pluto will reach opposition slightly before 3.00 am GMT on Friday 4 July 2014; this means that it will be directly opposite the Sun in the sky when viewed from Earth, on this occasion in the constellation...



At midnight between Thursday 3 and Friday 4 July 2014 the Earth will reach its aphelion, the furthest point in its orbit from the Sun, a distance of 152 093 481 km. The Earth's orbit is slightly eccentric and slightly variable, leading to the distance between the Earth and the Sun varying by about 3.4% over time, reaching aphelion early in July each year and perihelion (the closest point...




The planet Saturn will be at opposition (directly opposite the Sun) at about 6.00 pm GMT on Saturday 10 May 2014. This means that it will both be at its closest to the...


Follow Sciency Thoughts on Facebook.

Magnitude 6.1 Earthquake off the coast of Kyūshū Island, Japan.

The Japan Meteorological Agency recorded a Magnitude 6.1 Earthquake at a 'very shallow' depth about 50 km off the east coast of Kyūshū Island, slightly before 4.15 am Japan Standard Time on Friday 29 August 2014 (slightly before 7.15 pm on Thursday 28 August GMT). This is a large event, and closer to land would have been potentially very dangerous, but in this instance there are no reports of any damage or casualties.

The approximate location of the 29 August 2014 Kyūshū Earthquake. Google Maps.

Japan has a complex tectonic environment with four plates underlying parts of the Islands; in addition to the Pacific in the east and the Othorsk in the North, there are the Philipine Plate to the south and the Eurasian Plate to the West. Kyūshū 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. This is not a smooth process, with the two plates continuously sticking together then breaking apart as the presure builds up, leading to frequent Earthquakes in the region.

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...


On 20 December 2013 the Japan Meteorological Agency detected an increase in seismic activity beneath Aso (or Asosan) a volcanic caldera on central Kyūshū Island, Japan. This grew steadily for the next...



The Sakurajima Volcano, situated on an island in Kagoshima Bay, Kyushu, underwent a large explosive eruption on the morning of Friday 4 October 2013...



An eruption on Sakurajima Volcano, situated on an island in Kagoshima Bay, Kyushu, has coated the city...

Follow Sciency Thoughts on Facebook.

Satellite tagging Whale Sharks in the Red Sea.

Whale Sharks (Rhincodon typus) are the largest extant Shark species, and indeed the largest living Fish species of any kind, often exceeding 10 m in length. They are found in tropical and subtropical waters across the world, but there life-cycle and biology are poorly understood;  they are filter feeding planktivores, however unlike the slightly smaller Basking Sharks (Cetorhinus maximus) they do not feed directly on phytoplankton, instead actively feeding on zooplankton and small fish. Whale Sharks are listed as Vulnerable on the International Union for the Conservation of Nature’s Red List of Threatened Species. They have a long life cycle, a slow reproductive rate and a migratory lifestyle that moves them across many political boundaries, making them hard to protect for their entire life cycles. They appear to change their movement patterns at different stages in their life-cycles, with observed aggregations of Whale Sharks typically consisting of individuals of similar age. Whale Sharks have been targeted by fisheries in many parts of the Indo-Pacific region, and while many countries have now introduced laws to limit or ban exploitation, these are seldom enforced. Tellingly several countries have reported a drop in catch without a reduction in fishing effort, which is usually a sign of a declining population.

In a paper published in the journal PLoS One on 30 July 2014, a team of scientists led by Michael Berumen of the Red Sea Research Center of the King Abdullah University of Science and Technology discuss the results of a satellite tagging program carried out on Whale Sharks at an aggregation site near Al-Lith, on the Saudi Arabian Red Sea coast, and the data this revealed about the biology and movements of the Sharks.

A diver approaching a Whale Shark, Rhincodon typus. Red Sea Research Center.

The study was initiated after a number or reported Shark sightings by commercial dive boats, carrying tourists to popular locations on the reefs of the southern Red Sea. Juvenile Whale Sharks (2.5-7.0 m in length) were found to be gathering on the northern Shi’b Habil Reef, about 4 km off the coast of Al-Lith during the spring period, which is roughly March to May in the southern Red Sea. Sharks were approached by divers in 2009, 2010 and 2011, who attempted to assess their size and sex before attaching a satellite tag to the dorsal fin with a long pole. 47 of the 59 tags deployed operated for 11-135 days, with a failure rate of 20.4% (12 tags that did not work at all); such a failure rate is typical for such experiments, though why it occurred is unclear.

Study sites for Rhincodon typus in the Saudi Arabian Red Sea. (A) Location of the study area within the Red Sea. (B) Locations of 59 satellite tag deployments on juvenile Rhincodon typus near Al-Qunfudhah (n = 2) and Al-Lith (n = 57). (C) Detail of tag deployments around Shi’b Habil near Al-Lith (n = 55). Symbol color indicates the year of tag deployment. Berumen et al. (2014).


The Sharks were found to have a roughly evenly balanced sex ratio (18 male, 21 female and 18 undetermined individuals). Studies of older Whale Sharks in aggregations have found these gatherings to be heavily skewed in favour of one sex or the other, though at what point in their lives the Sharks segregate, or why they do so, remains unknown.

The majority of the Sharks remained within the southern Red Sea, at least for as long as the tags remained operational, apparently following a regular cycle in which they spend spring on the Saudi Arabian coast, then move to the Sudanese coast during the summer, then south to the Eritrean Coast in autumn, before recrossing the Red Sea to spend winter off the coast of Yemen, moving northwards back into Saudi Arabian waters in the spring again.

Movements of 47 Rhincodon typus tagged with satellite tags in the Saudi Arabian Red Sea: Most individuals (n = 39) made basin-scale movements within the southern Red Sea. Berumen et al. (2014).

Three of the tagged individuals moved northwards, reaching as far as Sharm el-Sheikh on the Egyptian Coast. Exactly why they did this is unclear; the waters of the southern Red Sea are considered to be more productive, and therefore presumably present better feeding opportunities to Whale Sharks, and were clearly favoured by the majority of individuals.

Movements of 47 Rhincodon typus tagged with satellite tags in the Saudi Arabian Red Sea: Three individuals performed excursions into the northern Red Sea as far as Sharm el-Sheikh. Berumen et al. (2014).

Five individuals moved out of the Red Sea altogether, moving through the Gulf of Aden then northward into the northern Indian Ocean. These individuals were in the 3-5 m size range (roughly in the middle of the sample size range, rather than at the upper end which might imply an age-related change in behaviour), and four of the individuals were of indeterminate sex, the remaining one being male, making it impossible to determine if this movement related to sexual segregation in maturing individuals. It does, however, imply that the population of Whale Sharks in the Red Sea is not separate from that in the western Indian Ocean, and that individuals move between the two groups.

Movements of 47 Rhincodon typus tagged with satellite tags in the Saudi Arabian Red Sea: Five sharks departed the Red Sea and moved into the Gulf of Aden and northern Indian Ocean. Berumen et al. (2014).

The Sharks were all spotted and tagged close to the surface, and spent the majority of their time in the upper 50 m of the water column, though only 16% of their time within 2 m of the surface. The Sharks occasionally went through periods of deeper foraging and would spend about 80% of their time in the 200-400 m zone. Deeper excursions were also fairly common, with Sharks making individual dives below 400 m, and in the case of three individuals, below 1000 m (maximum recorded depth 1360 m). The waters of the Red Sea are unusual in that there is little vertical temperature differentiation, with waters ranging from up to 34˚C at the surface to about 21.7˚C at 400 m, then remaining constant to a depth of about 3 km. This meant that diving Sharks within the Red Sea were never encountering temperatures lower than 21.7˚C, and that the depth to which they dove was probably more influenced by oxygen availability. This is interesting, as it has been suggested that the movements of Whale Sharks are largely influenced by water temperature. However the Sharks which left the Red Sea continued to dive regularly, encountering a minimum temperature of 8˚C in the Gulf of Aden, suggesting that the Sharks are able to tolerate at least short periods at much lower temperatures.

It is not clear exactly why the Whale Sharks congregate around the Shi’b Habil Reef in the spring, though it may be associated with Coral spawning, which in the southern Red Sea takes place around the full moons in April to June. This is supported by the presence of Manta Rays in the area at the same time (also large plankton feeders), though the Mantas spend the majority of their year in inshore waters around Al-Lith, and do not engage in deep-diving behaviour, suggesting there is only a limited overlap in diet between the two species.

See also…


Sawsharks (Pristiophoridae) are highly specialized...


Eagle Rays (Myliobatidae) are large Batoid Fish (bilaterally symmetrical fish with cartilaginous skeletons descended from Sharks), that predominantly live as free swimming animals in the water column rather than on the sea bottom. They are strong swimmers, and some...



Manta Rays, or Devilfish (Manta birostris) are the worlds largest Batoid Fish (bilaterally symmetrical fish with cartilaginous skeletons descended from Sharks)...


Follow Sciency Thoughts on Facebook.

Asteroid 2008 RG1 passes the Earth.

Asteroid 2008 RG1 passed by the Earth at a distance of about 10 210 000 km (26.56 times the average distance between the Earth and the Moon, or 6.8% of the average distance between the Sun and the Earth), slightly after 10.35 pm GMT on Monday 25 August 2014. There was no danger of the asteroid hitting us, though were it to do so it would have presented a serious threat. 2008 RG1 has an estimated equivalent diameter of 140-430 m (i.e. it is estimated that a spherical object with the same volume would be 140-430 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 with an energy equivalent to about 130-4000 megatons of TNT (roughly 7500-235 000 times the energy of the Hiroshima bomb). Such an event would result in a crater between 2.25 and 7 km across, cause devastation on a global scale and would have the potential to affect the climate globally for decades after the impact event.

The calculated orbit of 2008 RG1. JPL Small Body Database Browser.

2008 RG1 was discovered on 4 September 2008 by the Massachusetts Institute of Technology's Lincoln Near Earth Asteroid Research Laboratory in Socorro, New Mexico. The designation 2008 RG1 implies that it was the 32nd asteroid (asteroid G1) discovered in the first half of September 2008 (period 2008 R).

2008 RG1 has a 551 day year orbital period and an eccentric orbit tilted at an angle of 13° to the plane of the Solar System, which takes it from 0.73 AU from the Sun (i.e. 73% of the average distance at which the Earth orbits the Sun and slightly outside the orbit of Venus) to 1.90 AU from the Sun (i.e. 190% of the average distance at which the Earth orbits the Sun, considerably more than 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 close encounters between the asteroid and Earth are fairly common, most recent having occurred in August 2011 and  the next predicted in August 2017. As an asteroid on a trajectory which brings it extremely close to Earth which is large enough to cause serious harm should it collide with Earth it is also classified as a Potentially Hazardous Asteroid.

See also...


Comet C/2014 E2 (Jacques) passed the Earth at a distance of 0.56 AU (i.e. 56% of the distance between the Earth and the Sun, about 84 million km) on Thursday 28 August 2014. This is not a close...



Asteroid 2014 OO392 passed by the Earth at a distance of 16 810 000 km (43.74 times the average distance between the Earth and the Moon, or 11% of the average distance between the Earth and the...



Comet C/2012 K1 (PANSTARRS) will reach its perihelion (the closest point on its orbit to the Sun)  on Wednesday 27 August 2014, though it will not be visible until the end of September, when it will...


Follow Sciency Thoughts on Facebook.