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Comets

Fireball

Meteor fireball streaks across Australian skies

Fireball over Australia
© Screenshot YouTube
A screenshot from a YouTube video that is reportedly of the meteor that flew across the South East sky on the night of July 5.
Social media is buzzing with reports of a meteor spotted over the South Coast on Friday night.

On the Facebook group Australian Meteor Reports, administrator David Finlay said the meteor was spotted about 9pm on July 5 and believed it had come to ground somewhere in Victoria.

"I have reports of sonics from Forest Hill (Melbourne) to Mallacoota Vic. That's a distance of 400km. I've never heard of sonics being reported so far apart," he said in a Facebook post to the group.

He said sightings had been reported from as far north as Sydney and Orange.

"From these reports, and as long as this object was over land and not the ocean, I'm already predicting there are now meteorites on the ground somewhere in Victoria from this fall," he said.

Fireball 5

Nuke sensors detect asteroid explosion in the atmosphere over the Caribbean

Asteroid Explosion
© William Straka III/University of Wisconsin
On June 22nd at 21:25 UT, a small asteroid entered Earth's atmosphere and exploded in broad daylight south of Puerto Rico. Airwaves recorded by the Comprehensive Nuclear Test Ban Treaty Organization's infrasound station in Bermuda pegged the blast energy between 3 and 5 kilotons of TNT-a fraction of a WW II atomic bomb. The explosion was clearly visible in images from NOAA's GOES-16 weather satellite:


Meteor expert Peter Brown of the University of Western Ontario says the infrasound signal is consistent with a "small multi-meter sized near-Earth asteroid." According to data compiled by NASA's Center for Near Earth Object Studies, asteroids of this size and energy hit Earth's atmosphere about once a year. That means it's rare-but not exceptionally so.

Comet 2

ESA puts comet mission on fast track

Montezuma observing a comet.
© DEA / G. DAGLI ORTI/Getty Images
A sixteenth century illustration showing Montezuma observing a comet. The European Space Agency has a different plan.
Scientists at the European Space Agency (ESA) are working on a new "fast" mission to make the first flyby of a pristine comet - meaning one that has never before passed close to the sun.

Since the first comet mission, all the way back in 1978, numerous space agencies have made more than a dozen comet flybys, including one rendezvous and landing.

But never before has a mission attempted to visit a comet on its first plunge toward the sun, when its never-before-heated surface is almost unchanged from when it formed at the dawn of the solar system, some 4.5 billion years ago.

The recently approved mission, called Comet Interceptor, will also be unique in what it does as it nears its target.

Rather than simply flying by, it will split into four parts, each of which will whizz past the comet on a slightly different trajectory.

Three of these will be tiny instrument packages, which will view the comet from different angles. This will allow scientists back on Earth to create detailed 3D models not only of its surface, but of the gas, dust, and plasma surrounding it.

The fourth will be the mother ship, which will collect data from the smaller probes and relay it back to Earth.

"It's a novel concept," says Fabio Favata, head of the Strategy, Planning, and Coordination Office in ESA's Directorate of Science.

Details of the mission have yet to be determined, but the use of the word "fast" in its description doesn't mean it will be traveling at warp speed.

Fireball

Meteor fireball sends shockwaves over Queensland, Australia

meteor
Weather monitoring cameras have captured the moment a meteor exploded over Queensland, Australia on Saturday night (June 22)

According to the operator of the cameras, the blast at 10 pm sent shockwaves towards the Brisbane area.

A second camera showed the blast lighting the sky green above homes in the city of Ipswich.

Fireball 5

Massive meteor fireball last month turned night into day in Adelaide, Australia

A late night sight that definitely woke up countless residents!

Fireball over Adelaide
© YouTube/Caters Clips
Late last month, Australia's Adelaide experienced a spectacular and somewhat alarming sight as a fireball released a massive flare in the night sky before plummeting to Earth.

The meteor, captured on the Royal Adelaide Hospital's helipad camera, shined so bright that it made the sky appear to be in mid-sunrise at one point.

Info

Oldest meteorite collection on Earth found in the Atacama Desert

Meteorite recovery campaign
© Photo by Katherine Joy (University of Manchester)
Meteorite recovery campaign in the Atacama Desert (Nov. 2017).
Boulder, Colo., USA: Earth is bombarded every year by rocky debris, but the rate of incoming meteorites can change over time. Finding enough meteorites scattered on the planet's surface can be challenging, especially if you are interested in reconstructing how frequently they land. Now, researchers have uncovered a wealth of well-preserved meteorites that allowed them to reconstruct the rate of falling meteorites over the past two million years.

"Our purpose in this work was to see how the meteorite flux to Earth changed over large timescales-millions of years, consistent with astronomical phenomena," says Alexis Drouard, Aix-Marseille Université, lead author of the new paper in Geology.

To recover a meteorite record for millions of years, the researchers headed to the Atacama Desert. Drouard says they needed a study site that would preserve a wide range of terrestrial ages where the meteorites could persist over long time scales.
Meteorite in Atacama Desert
© Photo by Jérôme Gattacceca (CEREGE)
Meteorite with thin, dark, fusion crust in the Atacama Desert.
While Antarctica and hot deserts both host a large percentage of meteorites on Earth (about 64% and 30%, respectively), Drouard says, "Meteorites found in hot deserts or Antarctica are rarely older than half a million years." He adds that meteorites naturally disappear because of weathering processes (e.g., erosion by wind), but because these locations themselves are young, the meteorites found on the surface are also young.

"The Atacama Desert in Chile, is very old ([over] 10 million years)," says Drouard. "It also hosts the densest collection of meteorites in the world."

Comet

Taurid comet debris may raise chances of impacts on Earth in June

Tunguska Event
© Western University
An expedition in 1929 discovered the extent of the damage caused by the Tunguska Event in 1908.
A new study from Western University posits proof to the possibility that an oncoming swarm of meteors - likened to the Loch Ness Monster and Bigfoot by some extraterrestrial experts - may indeed pose an existential risk for Earth and its inhabitants. (That's us.)

When considering catalysts for catastrophic collision, there are two main sources Near Earth Objects (NEOs) like asteroids and meteoroids and interlopers from the outer solar system, which are typically comets. Over the past few decades, a great deal of effort has been expended in cataloguing more than 90 per cent of the potentially hazardous NEOs, and work is ongoing to detect, catalogue and track greater numbers and smaller sizes of these objects. Interlopers from the outer solar system are much harder to chart but again, much work is underway.

The Taurid swarm is a third potential source of risk that changes the probabilities of possible catastrophic impacts. The Tunguska (Russia) explosion of 1908 is considered a one-in-1000-year event, assuming a random distribution of events over time. But the Taurid swarm, a dense cluster within the Taurid meteoroid stream, and through which the Earth periodically passes, changes the odds significantly and gives a possible reason for the unlikely occurrence that a once per 1000-year event occurred just over a century ago. If the hypothesized might of the Taurid swarm is successfully proven, this also heightens the possibility of a cluster of large impacts over a short period of time.

Comet

'Oumuamua was a fragment from a disintegrated comet

Oumuamua
© ESO / M. Kornmesser
One artist's impression shows ʻ1I/'Oumuamua as a cigar-shaped object.
'Oumuamua's strange trajectory back out to interstellar space can be explained if the object was a comet fragment with the density of air.

'1/'Oumuamua, the interstellar mystery object that briefly visited the inner solar system in 2018, has proven a difficult nut to crack. Astronomers are still arguing about what it even is - asteroid, comet, or something else altogether? Now, in a pair of studies posted recently on the arXiv (paper 1, paper 2), Zdenek Sekanina (JPL-Caltech) suggests the object might be an ultra-low density fragment from a comet that disintegrated while passing near the Sun.

Info

New study confirms Libyan Desert Glass formed by airburst

Libyan Desert
© Associated Press
In the remote desert of western Egypt, near the Libyan border, lie clues to an ancient cosmic cataclysm.

Libyan desert glass is the name given to fragments of canary-yellow glass found scattered over hundreds of kilometres, between giant shifting sand dunes.

Interest in Libyan desert glass goes back more than 3,000 years. Among items recovered from King Tut's burial chamber is a gold and jewel-encrusted breastplate. In the centre sits a beautiful scarab beetle, carved from Libyan desert glass.

Libyan desert glass - raw and carved - is easily available today, but how the glass formed has long puzzled scientists.

Our research has found the answer.

Fireball 2

Meteor fireball lights up Northern New Zealand's sky

Meteor Over NZ
© ABC
Kiwis and Australians witnessed a short but stunning light show as a meteor burnt up in the atmosphere just after midnight.
Kiwis and Australians witnessed a short but stunning light show in our skies this morning as a meteor burnt up in the atmosphere just after midnight.

At around 12.25am Northlanders were woken to a flight of light, a deep rumbling and a flash of colour flying off the burning meteor.

Locals took to social media to describe what they saw and heard, with many revealing they thought it was a supersonic aircraft.

"It was a meteor. I saw it really close overhead at Oromahoe shortly after midnight. I could see green, yellow, orange flames coming off the rock as it burnt up," described one Northlander.

"It was very close and incredibly bright and afterwards there was a long rumbling sound. It was certainly bright enough to be seen at Paihia and Kaikohe."