Showing posts with label Fireballs. Show all posts
Showing posts with label Fireballs. Show all posts

Monday, 17 August 2026

The Kappa Cygnid Meteor Shower.

The Kappa Cygnid Meteor Shower is visible some years between the months of June and September, peaking between 3 and 25 August, with the best peak rate generally falling before dawn on 18 August, when the shower can produce 2-3 meteors per hour, with these tending to be bright fireballs with multiple fares. The meteor shower gains its name from the star Kappa Cygnus, which it is close to at the peak of its activity, and which is circumpolar in the Northern Hemisphere (i.e., close to the North Pole, and permanently above the horizon), although generally invisible in the Southern Hemisphere. If the shower does appear, viewing should be reasonably good, as activity will peak two days before the first quarter Moon, which will be in the constellation of Virgo, providing minimal light interference. However, the meteor shower is notoriously erratic, not being seen every year; it was last seen in the Augusts of 2020 and 2021, and before that in 2013 and 2014, then before that in 2007.

The radiant point of the Kappa Cygnid Meteor Shower. The Sky Live.

Meteor showers are thought to be largely composed of material from the tails of comets. Comets are composed largely of ice (mostly water and carbon dioxide), and when they fall into the inner Solar System the outer layers of this boil away, forming a visible tail (which always points away from the Sun, not in the direction the comet is coming from, as our Earth-bound experience would lead us to expect). Particles of rock and dust from within the comet are freed by this melting (strictly sublimation, transforming directly from a solid to a gas due to the low pressure on it's surface) of the comet into the tail and continue to orbit in the same path as the comet, falling behind over time.

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob.

The source body of the Kappa Cygnid Meteors remains somewhat of an enigma. The low number of asteroids, and their irregular arrival, suggests they are an old shower potentially derived from an object no longer visiting the Inner Solar System, whereas the brightness of the meteors suggests a younger origin. One possible solution to this is that they are derived from a body whose orbit undergoes a sinusoidal oscillation, something which can be caused if a body is forced into an orbital resonance with a larger body, often Jupiter in our Solar System. 

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

One potential parent body for the Kappa Cygnid Meteors which has been suggested is 2008 ED69, an asteroid which has an orbit with a 2:1 resonance with that of Jupiter and an orbital period of 4.96 years, which is thought to have been pushed into and out of Earth-crossing orbits repeatedly over the past 6000 years. However, more recent studies have established that the Kappa Cygnid Meteor Shower has an orbital period of 7.12 years and is locked into a 5:3 orbital resonance with Jupiter, ruling out 2008 ED69 as a potential parent body.

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Monday, 16 March 2026

Meteorite fragments recovered in Germany after fireball seen over northwestern Europe.

More than 3000 witnesses in Belgium, France, Germany, Luxembourg, and the Netherlands have reported observing a bright fireball meteor at about 6.55 pm local time (about 5.55 pm GMT) on Sunday 8 March 2026, with some witnesses also reporting a sonic boom. The meteor is described as having moved from southwest to northeast for about six seconds before exploding in a fireball over the German state of Rhineland-Palatinate. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. 

A very bright fireball moving from the southwest to the northeast was observed by many people in Belgium, France, Germany, Luxembourg, and the Netherlands. Bernd Klemt/AllSky7 fireball network/European Space Agency.

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. The brightness of a meteor is caused by friction with the Earth's atmosphere, which is typically far greater than that caused by simple falling, due to the initial trajectory of the object. Such objects typically eventually explode in an airburst called by the friction, causing them to vanish as a luminous object. However, this is not the end of the story as such explosions result in the production of a number of smaller objects, which fall to the ground under the influence of gravity (which does not cause the luminescence associated with friction-induced heating).

These 'dark objects' do not continue along the path of the original bolide, but neither do they fall directly to the ground, but rather follow a course determined by the atmospheric currents (winds) through which the objects pass. Scientists are able to calculate potential trajectories for hypothetical dark objects derived from meteors using data from weather monitoring services.

Shortly after the meteor was sighted, two residents of a flat in the German city of Koblenz reported an impact which had caused a football-sized hole in their roof, as well as damage to a tiled floor in the room underneath. A search of the flat yielded eleven fragments of rock with masses of between 6 and 161 g. A number of smaller fragments were subsequently found in a neighbouring courtyard by professional meteorite-hunters and sold. Police in Koblenz have subsequently issued a warning to other meteorite-hunters in the area to respect private property, and not to collect suspected fragments from areas which they have not been given permission to enter.

The largest of the meteorite fragments recovered from a home in Koblenz, Germany, weighing 161 g. SWR.

The meteorite fragments have a pale interior and a near-black crust, making it likely that they are a type of stoney meteorite called a HED (howardite–eucrite–diogenite) achondrite breccia. These meteorites resemble terrestrial igneous rocks, and are therefore presumed to have come from a body large enough for magma differentiation and igneous processing to have occurred. HED meteorites comprise about 5% of all meteorites recovered on Earth, and about 60% of achondritic meteorites (meteorites which do not contain chondrules, spherules of glassy material thought to have formed from molten droplets in space before being incorporated into larger bodies).

Fragments of probable HED meteorite recovered from a flat in Koblenz, Germany. SWR.

While HED meteorites vary somewhat in composition, all are thought to derive from the surface of the Asteroid 4 Vesta. Studies of these meteorites have produced crystallisation ages of between 4.43 and 4.55 billion years, and all show signs of having formed in an environment where igneous differentiation has occurred. These meteorites are thought to have been dislodged from the surface of their parent body by ancient impacts.

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Monday, 10 November 2025

Bright fireball over Florida probably caused by space junk.

Witnesses In Florida, Georgia, South Carolina, North Carolina, Tennessee, Alabama, Louisiana, Mississippi, and Arkansas have reported observing a bright fireball meteor at about 6.15 am local time (about 11.15 am GMT) on Saturday 8 November 2025, with some witnesses in Florida and Georgia also reporting a sonic boom. The fireball is described as having moved from northwest to southeast, appearing over southern Georgia and disappearing off the east coast of Florida. A fireball is defined as a meteor (shooting star) brighter than the planet Venus. 

The 8 November 2025 Florida fireball seen from the Merritt Island Wildlife Preserve in Titusville, Florida. Richard Gallagher/Florida Today.

Such 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, which appears to have been the case on 8 November. The object was visibly quite large, was relatively slow moving, and could be seen to break into a number of pieces as it passed through the atmosphere, none of which are conclusively signs of a man made object, but which combined together make this more likely. However, the nature of that object is unclear; the most common explanation for such re-entries is material falling back to Earth from a rocket launch, but while such a launch had been planned in Florida for that morning, it had not been due until an hour after the fireball event, and was eventually cancelled due to weather concerns.

Heat map showing areas where sightings of the meteor were reported (warmer colours indicate more sightings), and the apparent path of the object (blue arrow). American Meteor Society.

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Monday, 18 August 2025

Fireball over Arkansas and Missouri.

Witnesses across Arkansas, Iowa, Illinois, Indiana, Kentucky, Louisiana, Mississippi, Missouri, Oklahoman Tennessee, and Texas have reported observing a bright fireball meteor slightly after 1.30 am local time (slightly after 6.30 am GMT) on Sunday 17 August 2025. The fireball is described as having moved from southeast to northwest, appearing to the northwest of Walnut Ridge and disappearing close to Reeds Spring. 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 17 August 2025 fireball meteor seen from Waxahachie, Texas. Garrett Griffen/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. The brightness of a meteor is caused by friction with the Earth's atmosphere, which is typically far greater than that caused by simple falling, due to the initial trajectory of the object. Such objects typically eventually explode in an airburst called by the friction, causing them to vanish as a luminous object. However, this is not the end of the story as such explosions result in the production of a number of smaller objects, which fall to the ground under the influence of gravity (which does not cause the luminescence associated with friction-induced heating).

Heat map showing areas where sightings of the meteor were reported (warmer colours indicate more sightings), and the apparent path of the object (blue arrow). American Meteor Society.

These 'dark objects' do not continue along the path of the original bolide, but neither do they fall directly to the ground, but rather follow a course determined by the atmospheric currents (winds) through which the objects pass. Scientists are able to calculate potential trajectories for hypothetical dark objects derived from meteors using data from weather monitoring services.

See also...

Wednesday, 4 June 2025

The Nqweba Bolide and Meteorite Fall Event.

It is thought that more than a hundred tons of cosmic debris enters the Earth's atmosphere every day, mostly in the form of micrometeorites, dust-to-gravel sized particles. Most particles entering the upper atmosphere are derived from the tails of comets, but others are remnants of the original protoplanetary disc from which the Solar System formed, or fragments from the surface of other planets or moons, knocked free by earlier impacts. When these objects enter the atmosphere, they generally do so at very high velocities, causing them to heat rapidly as they pass through the atmosphere, and causing their surfaces to melt and the surrounding gasses to ionise. This can result in a bright streak across the sky called a meteor.

Larger bodies penetrate further into the atmosphere, burning longer and brighter, with those a few tens of centimetres in diameter producing meteors brighter in the sky than the planet Venus, which are termed 'fireballs'. Particularly large fireballs can sometimes be seen to visibly disinitegrate, and are known as bolides. The break up of such bolides is often audible from the ground, although, since they are typically tens of kilometres high, the sound typically reaches observers some time after the visible meteor, which can be confusing.

In a paper published in the South African Journal of Science on 29 May 2025, Roger Gibson of the School of Geosciences at the University of the Witwatersrand, Timothy Cooper of the Comet Asteroid and Meteor Section of the Astronomical Society of Southern Africa, Leonidas Vonopartis, also of the School of Geosciences at the University of the Witwatersrand, Carla Dodd of the Department of Geosciences and Institute for Coastal and Marine Research at Nelson Mandela University, Peter Hers of the Garden Route Centre of the Astronomical Society of Southern Africa, and Lewis Ashwal and Robyn Symons, once again of the School of Geosciences at the University of the Witwatersrand, describe a bolide event which took place over the coastal belt between Mossel Bay and Gqeberha, and as far north as the southern Karoo, on 25 August 2024.

Slightly before 9.00 am on Sunday 25 August 2024, residents of the area between Mossel Bay and Gqeberha and the southern Karoo heard a noise described as like rolling thunder which persisted for more than 30 seconds, despite the sky being clear of thunderclouds. Some residents of this area also reported ground tremors.

This provoked a great deal of speculation on social media, with people hypothesizing an earthquake, landslide, vehicle collision, aircraft crash, gas or electrical infrastructure explosion, or other events. At 9.02 am, Zoë van der Merwe of Cape St Francis posted a a cluster of rapidly moving, bright, silver-white fireballs in the sky that extinguished within seconds in the general vicinity of Gqeberha.

Selected frame-by-frame analysis of Zoë van der Merwe’s video (reproduced with permission) showing the bolide post-disruption phase with multiple secondary fragments flaring individually over about two seconds before entering dark flight. Gibson et al. (2025).

There is currently a global effort to better understand atmospheric fireball events, involving organisations in many different parts of the world. In Southern Africa, the Astronomical Society of Southern Africa maintains a database of fireball events, with a dedicated webpage where members of the public can report events. They also actively seek out reports of fireballs on social media, and quickly became aware of Zoë van der Merwe's post, and other reports of the Nqweba event, leading them to share reporting guidelines on social media groups. They also received reports of a bulletin on Luister FM, a radio station based in Port Elizabeth, which stated that a meteorite had been observed falling into the sea off the Eastern Cape at around 8.55 am.

Armed with these sources of data, they set out to determine whether the observed objects were in fact derived from a Solar System body, rather than being Human-made space junk re-entering the atmosphere. This is less complex than it sounds, as space junk will typically enter the atmosphere at a low angle and with a slow velocity, most often as a series of such events as debris from the same object falls to Earth. The Nqweba object did not fit this profile, and its occurrence did not coincide with any known satellite debris re-entering the atmosphere, making unlikely that it was space junk.

Initial reports all suggested that the bolide was moving out to sea, possibly splashing down in Jeffreys Bay, to the west of Gqeberha. As more reports came in it became it had been seen over a much wider area, north as far as Petrusburg, and west as far as Ceres. A further three videos of the object emerged, although the one taken by Zoë van der Merwe appears to cover the final part of the meteor's journey.

Shortly before 9.00 am, residents of Nqweba (formerly Kirkwood), about 100 km to the north of Cape St Francis, heard what they described as a loud thunderclap, followed by a long rumbling noise. Slightly after this, 9-year-old Eli-zé du Toit observed something falling through a large Wild Fig tree in her parents garden. When investigated, this turned out to be a rock smaller than her fist, with a shiny black crust, broken in places to reveal a light grey, concrete-like interior. When touched, the exterior layer of this rock was hot, while the interior was cold. Eli-zé's mother, Jesica Botha, posted several images of this and other fragments found in the garden to social media groups, leading to her being contacted by Carla Dodd of Nelson Mandela University.

(a) Photo of main meteorite mass retrieved by Eli-zé du Toit, displaying black fusion crust (top) and the grey interior containing multiple angular rock and mineral fragments. (b) Post submitted by Jesica Botha on the Snow Report Southern Africa Facebook page. Gibson et al. (2025).

Carla Dodd was able to arrange for the meteorite fragments to be transported to Nelson Mandela University for safekeeping; meteorites, along with fossils and archaeological artefacts are protected in South Africa by the National Heritage Resources Act (1999). Here the fragments were weighed, examined and placed into desiccators for storage. This preliminary inspction suggested that the fragments belonged to a type of stoney meteorite called a HED (howardite–eucrite–diogenite) achondrite breccia. These meteorites resemble terrestrial igneous rocks, and are therefore presumed to have come from bodies large enough for magma differentiation and igneous processing to have occurred.

Initial witness reports, and the two sites where meteors were reported to have fallen to Earth, Nqweba and the sea off Cape St Francis, are about 100 km apart, suggesting that the bolide had followed a north-south trajectory, shedding fragments as it went, towards the sea. However, bolides are notoriously confusing for observers, due to the long gap between the visual fireball and the sound reaching witnesses. Careful examination of witness reports and data from remote observation stations eventually led Gibson et al. to conclude that the bolide moved southwest-to-northeast, first appearing off Mossel Bay and moving inland towards Nqweba.

The Nqweba Bolide was the 20th bolide recorded globally in 2024, and one of the smallest. It is thought to have been about 1 m in diameter when it entered the atmosphere, and to have released energy equivalent to that released by the detonation of 92 tons of TNT.

Since 1992, 493 fireball events have been recorded over South Africa, only about 3% of which have been visible during the day. The largest recorded bolide in Southern Africa was the 21 November 2009 event over northern South Africa and southern Botswana, which was probably about 200 times as large as the Nqweba Bolide, although no fragments of this were ever found.

Recovered meteorites in South Africa are strongly linked to observed meteorites, and particularly daytime events, with 21 of 51 known meteorites collected in South Africa connected to observed falls, 75% of these in the daytime. However, prior to the Nqweba Bolide,  the most recent of these fell on Lichtenburg, North West Province, in 1973, long before modern technology such as remote observation stations and mobile phones was available to help track these events.

South Africa is currently increasing its remote observation capacity, and therefore its ability to track fireballs.  It is currently home to 16 cameras running under the auspices of the NASA SETI Institute Cameras for Allsky Meteor Surveillance network, and a further ten operated by the Global Meteor Network (4 of which have been installed in Western Cape schools to promote STEM activities). These are already improving fireball-detection rates, but do not work well in daylight. The collection of meteorite fragments is largely dependent on direct observation of the objects falling, as was the case with the Nqweba Meteorite Fall, but networks of cameras can help triangulate the area in which meteorites might have fallen, improving the chances of finding meteorites which were not directly observed.

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