Asteroid 2024 RL8 passes the Earth.

Asteroid 2024 RL8 passed by the Earth at a distance of about 329 350 km (1.12 times the average distance between the Earth and the Moon, or 0.29% of the distance between the Earth and the Sun), with a relative velocity of about 13.33 km per second, slightly before 10.40 pm GMT on Wednesday 11 September 2024. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2024 RL8 has an estimated equivalent diameter of 6-19 m (i.e. it is estimated that a spherical object with the same volume would be 6-19 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) between 40 and 22 km above the ground, with only fragmentary material reaching the Earth's surface.

300 second image of 2024 RL8 taken with the Elena Planetwave 17" Telescope at Ceccano in Italy on 9 September 2024. The asteroid is the small point at the centre of the image, indicated by the white arrow, the longer lines are stars, their elongation being caused by the telescope tracking the asteroid over the length of the exposure. At the time when the image was taken, the asteroid was about 2.5 million km from the Earth. Gianluca Masi/Virtual Telescope Project.

2024 RL8 was first detected on 7 September 2024 (four days before its closest approach to the Earth), by the University of Hawaii's PANSTARRS2 telescope. The designation 2025 RL8 implies that it was the 211th asteroid (asteroid L8 - in numbering asteroids the letters A-Z, excluding I, are assigned numbers from 1 to 25, with a number added to the end each time the alphabet is ended, so that A = 1, A1 = 25, A2 = 49, etc., which means that L8 = (25 x 8) + 11 = 211) discovered in the first half of September 2024 (period 2024 R; the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

The relative positions of 2024 RL8 and the Earth on at 11.00 pm on Wednesday 11 September 2024. JPL Small Body Database.

2024 RL8 is calculated to have a 480 day (1.31 year) orbital period, with an elliptical orbit tilted at an angle of 12.01° to the plain of the Solar System which takes in to 0.71 AU from the Sun (71% of the average distance at which the Earth orbits the Sun, and slightly inside the orbit of Venus) and out to 1.69 AU (1.69 times the distance at which the Earth orbits the Sun, more than the distance at which the planet Mars orbits). 

The positions and orbits of 2024 RL8 and the planets of the Inner Solar System at 11.00 pm on Wednesday 11 September 2024. JPL Small Body Database.

2024 RL8 is therefore classed as an Apollo Group Asteroid, which is an asteroid that is on average further from the Sun than the Earth, but which does get closer. 2024 RL8 is calculated to have fairly regular close encounters with the Earth, with the last thought to have happened in September 2020 and the next predicted for August 2028. The asteroid is also predicted to have regular close encounters with the planet Venus, with the last thought to have happened in June 2019 and the next predicted for June 2027.

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Passage of Typhoon Yagi kills at least 39 people across the Philippines, South China, and Vietnam.

Typhoon Yagi is now known to have killed at least 39 people as it swept across the  Philippines, South China, and Vietnam between 2 and 7 September 2024. The storm was initially detected as a low pressure system to the northwest of Palau by the Japan Meteorological Agency on 30 August 2024. By 1 September it has moved to the northeast, gaining in strength to become a tropical depression as it entered the Philippine Area of Responsibility (an area of the northwest Pacific monitored by the Philippine Atmospheric, Geophysical and Astronomical Services Administration. The system was identified as Tropical Depression 12W by the Joint Typhoon Warning Center, and named Enteng by red by the Philippine Atmospheric, Geophysical and Astronomical Services Administration, then as it intensified to become a tropical storm, formally named Tropical Storm Yagi by the Japan Meteorological Agency.

Typhoon Yagi made landfall in Aurora Province on Luzon Island, the Philippines, at about 2.00 pm local time on Monday 2 September, taking fifteen hours to move across the island before emerging over the South China Sea at about 3.00 am on Tuesday 3 September. During this time the storm lost considerable energy, particularly as it passed over the Cordillera Central mountain range, but still causing significant disruption. The storm raised the waters of the Marikana River, which flows through eastern Manila, to rise by 16 m, leading to flooding in the Metro Manila area, as well as in the provinces of Bulacan, Camarines Norte, Camarines Sur, Cavite, Laguna, Northern Samar, Pangasinan, and Rizal. A number of ships were driven aground in Manila Bay, with two colliding and catching fire. Twenty people are currently known to have died as a result of the storm on Luzon, nine of them in Rizal Province, with at least more 26 missing and at least eighteen injured. Around 28 000 people in Metro Manila, Calabarzon, and Bulacan, lost their electricity supplies during the storm, schools were closed for two days, and most flights to and from Luzon Island cancelled. About 80 000 people were evacuated from low-lying areas, with 459 homes destroyed and another 6128 damaged. Several dams had to be opened to prevent them being damaged by high waters, adding to the flooding in areas beneath them.

Flooding in Rizal Province, the Philippines, on 2 September 2024. AP. 

After passing over Luzon Tropical Storm passed across the South China Sea, merging with a smaller depression and gaining significantly in strength as it moved west towards China. By 5 September the storm had gained suficient energy that the Japan Meteorological Agency upgraded it to a Super Typhoon, which is to say a typhoon with windspeeds of 240 km per hour or above, the equivalent to a Category 4 or 5 storm on the Saffir–Simpson scale.

In preparation for this 420 000 people were evacuated from low-lying areas on Hainan Island, and 500 000 from low-lying areas in Guangdong Province, with widespread cancelation of flights, non-essential travel, and coastal activities in both provinces as well as Hong Kong.

Typhoon Yagi made landfall near the city of Wenchang on Hainan at about 4.20 pm local time on Friday 6 September, bringing with it sustained windspeeds of 195 km per hour, making it the strongest storm to hit the island since Typhoon Ramassun in 2014. It passed across the island making, and over the provincial capital, Haikou, before briefly making landfall in Xuwen County, Guangdong Province, then passing out over the Gulf of Tonkin. Four people are reported to have lost their lives on Hainan Island, with another 95 injured, and 1.2 million people losing electricity supplies. Aa further nine people were injured in Hong Kong.

Heavy rainfall and fallen trees in Wenchang City on 6 September 2024. Luo Yunfei/China News Service/VCG/Getty Images.

Typhoon Yaagi gained in strength again as it passed over the Gulf of Tonkin, reaching Vietnam as a Category 4 Typhoon (i.e. a storm with sustained winds in excess of 209 km per hour), making it one of the strongest storms ever to hit northern Vietnam. In preparation for the storm schools were closed and fishing and outdoor gatherings advised against, as well as most flights, ferry services, and sporting events cancelled. The storm made landfall over the city of Haiphong, binging high winds and extensive flooding to the Red River Valley. fifteen people are known to have died in Vietnam, including four people hit by flying debris, another four, described as a family, by a landslide in Hoa Binh, and another man in Hai Dong hit by a falling tree.

High winds caused by Typhoon Yagi on the shore of Phuong Luu Lake in Haiphong. Nhac Nguyen/AFP.

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. They have different names in different parts of the world, with those in the northwest Pacific being referred to as typhoons.

The structure of a tropical cyclone. Wikimedia Commons.

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. 

The formation and impact of a storm surge. eSchoolToday.

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Asteroid 2024 RW1 impacts the Earth.

On the morning of Wednesday 4 September 2024, planetary scientist Jacqueline Fazekas working at the University of Arizona's Catalina Sky Survey detected a fast moving object, which she interpreted as a potential Near Earth Asteroid. She reported this to the International Astronomical Union's Minor Planet Center, where it was given the provisional designation CAQTDL2. This initial discovery was followed by a series of further sightings from other observatories, confirming that the object was an asteroid, which was then named 2024 RW1, and that it was on a collision course with the Earth.

Discovery images of Asteroid 2024, within purple circles. Catalina Sky Survey.

The designation 2024 RW1 implies that the asteroid was the 47th asteroid  (asteroid W1 - in numbering asteroids the letters A-Z, excluding I, are assigned numbers from 1 to 25, with a number added to the end each time the alphabet is ended, so that A = 1, A1 = 26, A2 = 51, etc., which means that W1 = (25 x 1) + 22 = 47) discovered in the first half of September 2024 (period 2024 R - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

Asteroid 2024 RW1 is calculated to have had a 1450 day (3.97 year) orbital period, with an elliptical orbit tilted at an angle of 0.53° to the plain of the Solar System which took in to 0.74 AU from the Sun (74% of the distance at which the Earth orbits the Sun) and out to 4.23 AU (4.23 times the distance at which the Earth orbits the Sun, and almost three times the distance at which the planet Mars orbits). It is therefore classed as having been an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer). 

The calculated orbit of asteroid 2024 RW1. JPL Small Body Database.

Asteroid 2024 BX1 is calculated to have had four close encounters with the Earth before finally impacting, with the first in August 1912, and the most recent in October 2020. It has also had close encounters with Venus in June 1966 and January 2009, and Jupiter in November 2006 and September 2018. Asteroids 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.

By 11.00 am GMT on 4 September 2024, the European Space Agency had calculated that Asteroid 2024 RW1 would impact the Earth, entering the atmosphere at about 5.08 pm over or close to northern Luzon Island, the Philippines. In the event the asteroid entered the atmosphere at 4.46 pm GMT (0.46 am on 5 September, Philippines time) over the Pacific Ocean to the east of Luzon, producing a bright fireball meteor, with a distinct green colour, which probably indicates that it had a high magnesium content. 

A bright fireball meteor observed from Tuguegarao City in the Philippines on 5 September 2024, thought to have been caused by the impact of Asteroid 2024 RW1. Marvin Coloma/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 on this occasion the object is known to 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).

Based upon observations in space and on entry to the Earth's atmosphere, 2024 RW1 is calculated to have been about a metre in diameter, and to have had a high magnesium content, something which in turn implies a stony meteorite rich in the mineral olivine (counter to possible expectations, metallic meteorites seldom contain much magnesium). However, as it fell to Earth over the Pacific Ocean, it is unlikely that any fragments of the asteroid will be recovered to test this hypothesis. 2024 RW1 is the eighth asteroid ever to have been discovered before impacting the Earth.

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Archaeologists uncover grave of fourth century Alammani tribesman in Baden-Württemberg, southern Germany.

Archaeologists from the consultancy firm ArchaeoBW carrying out survey work at Gerstetten in Baden-Württemberg, southern Germany, for Stuttgart Regional Council ahead of a housing construction project have uncovered a wood-lined grave, according to a press release issued by the council on 27 August 2024. The grave, which was first discovered in May, contained a partial skeleton as well as some trade goods.

A partial skeleton uncovered in a grave site in Baden-Württemberg, southern Germany. Gizem Dakmaz/Stuttgart Regional Council.

Wooden graves of this type are associated with the Alammani, an ancient Germanic tribe first mentioned in Roman records by Lucius Cassius Dio in 213 AD. Such graves are typically date to the fourth century AD and are found in groups of five-to-twelve, and it is possible that other undiscovered graves lie close to the one discovered in Gerstetten. 

The skeleton and other items from the grave were taken to the laboratory of the State Office for Monument Preservation of Stuttgart Regional Council in Esslingen, where examination of the skeletal remains determined that they came from a man aged about 60. A radiocarbon date obtained from a rib suggest that the man died between 263 and 342 AD.

As well as the skeleton, a number of items interpreted as grave goods were also found, including a Roman-style glass cup, which may have come from the Roman fort of Guntia (modern Günzburg in Bavaria), two ceramic pots, similar in style to other pots known from the Middle Elbe-Saale region, and a bone comb.

Two ceramic pots from a fourth century grave site in Baden-Württemberg, southern Germany. Gizem Dakmaz/Stuttgart Regional Council.

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Magnitude 5.7 Earthquake in Eduardo Abaroa Province, Bolivia.

The United States Geological Survey recorded a Magnitude 5.7 Earthquake at a depth of 223 km in Eduardo Abaroa Province, Bolivia, slightly before  6.40 am local time (slightly before 10.40 am on Thursday 5 September 2024. Quakes at this depth are seldom dangerous, but are often felt over a wide area, and this one was reportedly felt on the coast of northern Chile.

The approximate location of the 5 September 2024 Eduardo Abaroa Province Earthquake. USGS.

Bolivia is located close to the west coast of South America, which is also the convergent margin between the Nazca and South American Plates. The Nazca Plate is being subducted beneath the South American Plate and is sinking beneath the South American Plate. This is not a smooth process, the rocks of the two plates continuously stick together then, as the pressure builds up, break apart again, causing Earthquakes. As the Nazca Plate sinks deeper it is partially melted by the friction and the heat of the Earth's interior. Some of the melted material then rises up through the overlying South American Plate as magma, fuelling the volcanoes of the Bolivian Andes. 

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