Astronomy

What could be the name of a huge asteroid I watched some years ago?

What could be the name of a huge asteroid I watched some years ago?



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Some years ago I was with my family in Venezuela. I'm not sure about the date/hour, but probably it was somewhat around 2007 in the afternoon. We were talking when one of us saw a huge meteor moving "slowly" from East to West. It was visually about 1/4 of a full moon size. It took a lot to get lost from our view (I'd say more than a minute). We could see the fireball burning and leaving the trail.

I never heard about this in the news and wanted to know if this same event is familiar to somebody else or if you've had a similar experience before.

I mean, this thing was huge and we were just waiting for it to crash but it seems we were lucky.

Edit:

It wasn't a satellite, since we could see the "rock". It wasn't like these meteors which you cannot distinguish the trace from the fireball.

I'm not sure about the date.


Meteors don't move slowly.

Large fireballs do occur, rarely, but they move pretty fast, a few seconds at most. Meteors that are bright enough to be seen in daylight are even rarer. When a meteor is falling you can't see the "rock". Even a large meteoroid is only a few metres across, and they are 50-100km up in the atmosphere, and surrounded by glowing plasma. Take a look at some of the videos of fireballs. Very few are during the day (because even bright fireballs are not clearly visible) and the few which are visible during the day are very well know (the 1972 daylight fireball or Cheblynsk)

What you saw cannot be a meteor. Because meteors don't look like that.

Re-entering space debris or satellites move more slowly, and can have more of a "burning" appearance than a meteor, but there is no mention of a satellite re-entry in the database: http://www.satobs.org/reentry/Visually_Observed_Natural_Re-entries_latest_draft.pdf For example on Jan 2007 the rocket for Corot-r (a space telescope launched by Russia) re-entered over the USA and generated many reports. That would not have been visible from Venezuela (and was in the middle of the night).

If you had an exact date then it would be possible to search more deeply, without it, this will probably remain a mystery. (I pondered briefly about a rocket launch from the Guiana site, but they always launch to the East, over the sea (for safety and efficiency) so that can also be excluded.


+1because although admittedly unusual sounding this is the right SE site to ask about this kind of thing and you're responsive to comments. In Aviation SE I have seen discussions of why under certain conditions planes climbing near an airport will sometimes appear to hover or move in an unnatural way, and I've seen it myself so I know the feeling. I don't know of any astronomical phenomenon that can make a visible and resolved (you can see the size) object move slowly across the sky. Weather balloon, plane, or other atmospheric object most likely.

Artificial satellites take a minute or two, but they are usually dim and only seen at night, at the brightness of unremarkable stars. The only exceptions to this that I know of are satellite flares which tend to last only seconds, or intentionally reflective satellites like the Humanity Star, Mayak (Маяк), or the Orbital Reflector.


Planetary defense experts use infamous asteroid Apophis to practice spotting dangerous space rocks

Apophis definitely won't hit Earth this month, but scientists are pretending it might.

Earth's most recent brush with asteroid danger was eight years ago, when a space rock the size of a six-story building came seemingly out of nowhere, injuring 1,200 people when it exploded over Chelyabinsk, Russia.

Now, scientists are using this month's flyby of the infamous asteroid Apophis to test their responses to potentially hazardous space rocks, honing the fine art of planetary defense. Planetary defense focuses on identifying asteroids and comets that hang out around Earth, mapping their precise paths and seeing how their orbits compare with Earth's.

If an orbital model shows that an asteroid and Earth are due to reach the same place at the same time, things get serious, particularly when the space rock is large. That's the sort of scenario that ended the dinosaurs' reign, after all. But planetary defense isn't hopeless: if humans identify a dangerous asteroid long enough before impact, we could theoretically do something to divert it.

Successfully preventing damage from an asteroid impact will depend on spotting the threat in time, which takes practice. But although scientists have identified more than 25,000 near-Earth asteroids to date, the majority are too small to cause much worry. So while there are plenty of asteroids rattling around Earth's orbit, most aren't big enough or close enough to trigger realistic existential angst.

Apophis came to its fame because it isn't like most of these near-Earth space rocks. When scientists discovered it in 2004, it stood out right away. First, it is relatively large &mdash more than 1,000 feet (300 meters) wide, around the height of the Eiffel Tower, according to NASA. And models based on early observations suggested a nearly 3% chance Apophis would collide with Earth on April 13, 2029.

More precise observations soon put the fear of impact that year to rest, but the early concern surrounding the asteroid prompted its name, which references an Egyptian "demon serpent who personified evil and chaos," as NASA put it. Right now, scientists are confident that Apophis is no threat to Earth for at least a few decades. But the space rock will still come visiting next month, offering scientists valuable opportunities to get a close look at a relatively large asteroid.

And, with a little imagination, these flybys can also serve as planetary defense rehearsals.

"The goal is to basically wrangle all the scientists from around the world, kind of the coalition of the willing," Vishnu Reddy, a planetary defense expert at the University of Arizona who is coordinating the project, told Space.com. "Then we go on this months-long campaign, trying to observe this object."

Apophis will fly past Earth on March 5. The asteroid will remain about one-tenth the average Earth-sun distance away &mdash a downright mundane flyby compared to the 2029 event, when Apophis will pass by at about the altitude at which particularly high satellites orbit.

To mark this year's flyby, the International Asteroid Warning Network instituted its third such campaign. Previously, scientists have practiced on an asteroid called 2012 TC4 and on 1999 KW4, which is a pair of rocks circling each other. For Apophis, about 40 scientists from 13 different countries have signed on. These observers are pretending that Apophis has never been seen before, which means they are starting from scratch in terms of evaluating how much danger the asteroid poses to Earth.

"It's not a scientific goal," Reddy said. "The goal is to get new observations as if we don't know anything about this object and try and see where in the process we need to improve efficiency and also identify the human factor. Anybody dealing with scientists knows that it's like herding cats, and when you do that on an international scale, there's part diplomacy, part science, and part planetary defense."

Reddy said that the coincidence of the Apophis flyby occurring during the continuing COVID-19 pandemic offered an opportunity to understand how resilient the asteroid detection system is. At this point, most telescopes are managing to continue operating, although he said the pandemic likely would have interfered much more had the flyby occurred a year earlier, when institutions were still scrambling to respond.

"There's a reasonable amount of redundancy in planetary defense," he said. "Even if one telescope goes down or we lose a certain thing, it's not like the whole community goes down, to some extent."


Comment AEC: The myths of Phaethon describes how the Sun ran off its course, came too close to the Earth and thus burnt the land. From all we know, such major, fast changes in Sun/ Earth’s motion are impossible. On the other hand, we have many modern day accounts of fireball running across the sky that were so bright that eye witnesses confused the entering meteor with the sun. Many of the witnesses to the Tunguska Meteor Explosion in Siberia in 1908 said they thought the sun had gone astray rushing across the sky, shortly after this, the explosion and fires destroyed an 40km-diameter area of forest. A recent meteor filmed over Finland “turned the night into day” and “shook the ground”, without causing damage on the surface. It is easy to see how a large passing object with a massive debit field or dust trail can caused widespread (regional or continental) fires, and the survivors are likely to believe it was the sun, especially in the case of a night time encounter. Thus, the Phaethon myth is almost certainly based on a true story. There is no indication that the soon to take place asteroid fly-by will cause any disturbances on Earth. The riddle here is why NASA would have named (in 1985) a harmless asteroid – which would at the very most caused a display of lovely shooting stars – after an ancient destructive event, which was locally perceived as the end of the world and in many cases, it was the end of their world.

On December 16, 2017, the modern day asteroid called Phaethon will approach within 0.069 au of Earth (27 lunar distances).

Here is the recent story by Metro.co.uk

It’s named after an ancient god who nearly wiped out humanity – so you be forgiven for feeling pretty nervous to hear about a gigantic three-mile-wide asteroid that’s set to zoom past Earth in December. A gigantic space rock called 3200 Phaethon is due to brush ‘quite close’ to our planet on December 17, Russian astronomers have revealed. This huge asteroid is thought to cause the beautiful Geminids meteor shower which will take place between December 13 and 14 as hundreds of bright meteors illuminate the night sky as they burn up in Earth’s atmosphere. But NASA has also described it as a ‘potentially hazardous asteroid whose path misses Earth’s orbit by only 2 million miles‘ – which is incredibly close in galactic terms. It’s about half the size of Chicxulub, the rock which wiped out the dinosaurs, and has a very unusual orbit which causes it to pass closer to the sun than any other named asteroid.

Astronomers from the Immanuel Kant Baltic Federal University have just published a video which tracks the path of Phaethon. In a statement, the uni wrote: ‘Apparently, this asteroid was once a much bigger object, but its many approaches to the Sun have caused it to crumble into smaller pieces which eventually formed this meteor shower. ‘If so, the asteroid itself could be the residue of a comet nucleus. The asteroid’s extremely elongated orbit, thanks to which it sometimes gets to the Sun closer than Mercury and it sometimes moves away farther than Mars, is another argument in favour of this theory.’ The space rock is named after Phaethon, the son of the Greek sun god Helios. Ancient myths told the story of how this rather insecure-sounding young god was challenged to prove he was related to Helios, who was said to pull the sun across the sky.

To prove his divine provenance, Phaethon decided to have a go in his dad’s chariot and was unable to control the horses, who then ran wild across the sky dragging the hot sun with them. Humanity was almost destroyed in the subsequent chaos, which scorched the Earth, burned vast amounts of vegetation and created the great deserts of Africa. The Earth was only spared when Zeus blasted the horses with a thunderbolt, killing Phaethon in the process. Here’s what the Greek philosopher Plato wrote about the myth: ‘There have been, and will be again, many destructions of mankind arising out of many causes the greatest have been brought about by the agencies of fire and water, and other lesser ones by innumerable other causes. ‘There is a story that even you [Greeks] have preserved, that once upon a time, Phaethon, the son of Helios, having yoked the steeds in his father’s chariot, because he was not able to drive them in the path of his father, burnt up all that was upon the earth, and was himself destroyed by a thunderbolt.

Now this has the form of a myth, but really signifies a declination of the bodies moving in the heavens around the earth, and a great conflagration of things upon the earth, which recurs after long intervals.’ We’re pleased to report that the real-life Phaethon will not plough into Earth and so our species will live to fight another day.


A Huge Asteroid or Ancient Volcano – What Really Wiped Out the Dinosaurs?

Some 66 million years ago, a catastrophic event took place on Earth — a super-powerful asteroid moving at about 40,000 miles an hour hit the Gulf of Mexico.

The impact caused devastation of unprecedented amounts. It would have left a crater miles deep in the crust of the Earth and more than 115 miles across, causing thousands of cubic miles of rock to disappear, according to the National Geographic. As the natural disaster unfolded, more than two-thirds of life on the planet — including dinosaurs — subsequently perished.

Dinosaurs of the Dashanpu Formation Photo by ABelov2014 CC BY-SA 3.0

The avian dinosaurs that survived evolved into birds. That is, for decades now, the major theory to explain how the dinosaurs vanished from among the living. The theory began to gain momentum during the 1980s and 1990s following the discovery of the Chicxulub Crater in the Gulf of Mexico.

It remained a piece of compelling evidence to support the asteroid theory over volcanism, perhaps until now. Ancient mega-volcanoes on the territory of modern-day India had a supportive or even major role in the decline and ultimate disappearance of dinosaur populations, researcher argue.

This shaded relief image of Mexico’s Yucatán Peninsula shows a subtle, but unmistakable, indication of the Chicxulub impact crater. Most scientists now agree that this impact was the cause of the Cretatious-Tertiary Extinction,

As National Geographic reports, two different research groups — one backed by Berkeley another by Princeton — sought after more answers on the matter and produced two studies, published in the journal Science in February 2019.

The research teams, who analyzed ancient rock deposits and used two different dating methods, tried to answer when exactly those ancient volcanic eruptions took place and how they may have affected life.

Crystals of epistilbite and calcite in a vug in Deccan Traps basalt lava from Jalgaon District, Maharashtra Photo by Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

The Deccan Traps, as the mega-volcanoes have been called, first erupted some 400,000 years before the great asteroid impact in Mexico, the researchers agreed. Their activity ceased some 600,000 years after the Cretaceous period ended (which is when dinosaur life came to an abrupt end). Of the total lava erupted within this time frame, as little as half of it discharged after the asteroid impact.

One of the studies still says that the Deccan Traps were significantly more active in the period before the impact. Active enough to jeopardize entire ecosystems and species before, finally, the mass extinction event was hurried by the asteroid.

Oblique satellite view of the Deccan Traps Photo by Planet Labs CC BY-SA 4.0

In contrast, the other study somewhat reduces the role of the volcanoes, saying that most of the lava spilled after the asteroid fell, the impact of which also caused a colossal earthquake, floods and strong gusts of winds — a phenomenon never felt by humans.

In the words of geochronologist Blair Schoene, lead author of the Princeton study, the overlap of both finds is still a “big improvement” compared to “20 years ago, or even 15 years ago, where [the two teams’ dating methods] couldn’t agree to better than a few percents, which here would be millions of years,” reports National Geographic.

Both teams conducted surveys in the Western Ghats mountain range in India, where the Deccan Traps once thrived, to reach their conclusions. The ancient volcanoes would have been overwhelmingly huge. If the entire amount of lava produced over their million-years of activity, it would be enough to cement the whole planet with a thick and solid layer of rock.

Deccan Traps at Ajanta Caves. Photo by Shaikh Munir – CC BY SA 4.0

If the greater portion of Deccan Traps material was released before the asteroid, then some of the gases emitted — such as carbon dioxide — could have easily created significant warming of temperatures.

In this case, the final 400,000 years of the Cretaceous Period would have been marked by a significant increase of global temperatures of about 14.4 degrees Fahrenheit. Some species perhaps adapted to the newly-created hot environments, but they would have been shocked to death by a nuclear winter effect triggered by the giant asteroid.

The impact of a meteorite or comet is today widely accepted as the main reason for the Cretaceous–Paleogene extinction event.

This scenario needs amending if the greater portion of Deccan Traps lava was discharged after the impact. More than that, it is possible that the concurring catastrophes acted interchangeably in regards to the mass extinction. It is the details that remain a subject of argument. Mega volcanoes such as those in ancient India are still capable of delivering a similar effect as the asteroid would have done. Another aspect is that the impact of the asteroid could have strengthened volcanism.

“The big question is, would the extinction have happened without the impact, given the volcanism, or conversely, would the extinction have happened without the volcanism, given the impact? I don’t think we know that answer,” Schoene told AFP. While the asteroid vs. volcanoes debate will still need to see its final conclusions, it is way better than some of the older and at times bizarre stuff proposed as an answer to what happened to dinosaurs.

Just to name one: a theory from the 1960s claimed that the Earth back then became so invaded by caterpillars that the insects ate most of the available vegetation — and this, not a volcano or an asteroid — left the dinosaurs to starve to death.


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Dust circulating in the atmosphere after an impact could have reduced the amount of sunlight reaching the earth, affecting plant growth and temperatures on earth.

Now Francis Thackeray of the Evolutionary Studies Institute at the University of the Witwatersrand in South Africa believes a platinum spike found in South Africa proves the extinction of many large animals globally could have been caused by one or multiple meteoroid impacts.

Researchers have discovered their first evidence in the southern hemisphere that a mini ice age almost 13,000 years ago may have been caused by clouds of dust thrown up by an asteroid impact (stock image)

Dr Thackeray who was working with researcher Philip Pieterse from the University of Johannesburg and Professor Louis Scott of the University of the Free State, said: 'Our finding at least partially supports the highly controversial Younger Dryas Impact Hypothesis (YDIH).

'We seriously need to explore the view that an asteroid impact somewhere on earth may have caused climate change on a global scale.

'And [it may have] contributed to some extent to the process of extinctions of large animals at the end of the Pleistocene, after the last ice age.'

Many mammals became extinct in North America, South America and Europe at the time of the Younger Dryas.

In South Africa a few extraordinary large animal species became extinct around that period including the giant African buffalo, a large zebra, and a very big wildebeest each weighing around 1,100lbs (500kg) more than its modern counterpart.

Human populations may also have been indirectly affected at the time in question.

Thackeray argues that a dramatic halt in the development of the use of stone tools by the Clovis people in North America and the Robberg stone artefacts used by populations in South Africa around that period could indicate that an asteroid may have caused global consequences.

Dr Thackery said: 'Without necessarily arguing for a single causal factor on a global scale, we cautiously hint at the possibility that these technological changes, in North America and on the African subcontinent at about the same time, might have been associated indirectly with an asteroid impact with major global consequences.'

WHEN WERE EARTH'S 'BIG FIVE' EXTINCTION EVENTS?

Traditionally, scientists have referred to the 'Big Five' mass extinctions, including perhaps the most famous mass extinction triggered by a meteorite impact that brought about the end of the dinosaurs 66 million years ago.

But the other major mass extinctions were caused by phenomena originating entirely on Earth, and while they are less well known, we may learn something from exploring them that could shed light on our current environmental crises.


Apophis

Asteroid 99942 Apophis is a near-Earth asteroid more than 1000 feet (over 300 meters) in size that will harmlessly pass close to Earth on April 13, 2029. When it was discovered in 2004, the asteroid caused a stir because initial calculations indicated a small possibility it would impact Earth in 2029.

After searching through some older astronomical images, scientists ruled out the possibility of a 2029 impact. It&rsquos now predicted the asteroid will safely pass about 19,800 miles (31,900 kilometers) from our planet&rsquos surface. While that&rsquos a safe distance, it&rsquos close enough that the asteroid will come between Earth and our Moon, which is about 238,855 miles (384,400 kilometers) away. It&rsquos also within the distance that some spacecraft orbit Earth.

It&rsquos rare for an asteroid of this size to pass so close to Earth, although smaller asteroids, in the range of 16 to 33 feet (5 to 10 meters), in size have been observed passing by at similar distances.

&ldquoThe Apophis close approach in 2029 will be an incredible opportunity for science,&rdquo said Marina Brozović, a radar scientist at NASA&rsquos Jet Propulsion Laboratory in Pasadena, California, who works on radar observations of near-Earth objects (NEOs). &ldquoWe&rsquoll observe the asteroid with both optical and radar telescopes. With radar observations, we might be able to see surface details that are only a few meters in size.&rdquo

During its 2029 flyby, Apophis will first become visible to the naked eye in the night sky over the southern hemisphere and will look like a speck of light moving from east to west over Australia. It will be mid-morning on the U.S. East Coast when Apophis is above Australia.

Apophis will then cross above the Indian Ocean, and continuing west, it will cross the equator over Africa.

At its closest approach to Earth, just before 6 p.m. EDT, April 13, 2029, Apophis will be over the Atlantic Ocean. It will move so fast that it will cross the Atlantic in just an hour. By 7 p.m. EDT, the asteroid will have crossed over the United States.

As it passes by Earth, it will get brighter and faster. At one point it will appear to travel more than the width of the full Moon within a minute and it will get as bright as the stars in the Little Dipper.

Apophis is named for the demon serpent who personified evil and chaos in ancient Egyptian mythology.

Exploration

Apophis was discovered on June 19, 2004, by astronomers Roy Tucker, David Tholen and Fabrizio Bernardi at the Kitt Peak National Observatory in Tucson, Arizona. They were only able to observe the asteroid for two days because of technical and weather problems. Fortunately, a team at the Siding Spring Observatory in Australia spotted the asteroid again later in the same year.

Since its discovery, optical and radar telescopes track Apophis as it orbits the Sun and scientists are confident they know its future trajectory. Current calculations show that Apophis still has a very small chance of impacting Earth &mdash less than 1 in 100,000 many decades from now.

The most important observations of Apophis will come during its close Earth flyby in 2029. Scientists around the world will study the asteroid&rsquos size, shape, composition and possibly even its interior.

Size and Distance

Apophis is a 1,120-foot-wide (340-meter-wide) asteroid. That&rsquos about the size of three-and-a-half football fields.

At its farthest, Apophis can reach a distance of about 2 astronomical units (One astronomical unit, abbreviated as AU, is the distance from the Sun to Earth.) away from Earth. It&rsquos expected to safely pass close to Earth &mdash within 19,794 miles (31,860 kilometers) from our planet&rsquos surface &mdash on April 13, 2029. This is the closest approach by an asteroid of this size that scientists have known about in advance.

Orbit and Rotation

The orbit of Apophis crosses the orbit of Earth. It completes an orbit around the Sun in a bit less than one Earth year (about 0.9 years). This places it in the group of Earth-crossing asteroids known as "Atens," whose orbits are smaller in width than the width of Earth's orbit, or 1 AU. As a result of its close encounter with Earth in 2029, the asteroid's orbit will be widened to become slightly larger than the width of Earth's orbit. At this point it will be reclassified from the Aten group to the "Apollo" group (the group of Earth-crossing asteroids with orbits wider than 1 AU).

The asteroid &ldquowobbles&rdquo as it spins about its short axis, typically rotating about once every 30 hours. Sometimes, there is also a &ldquorocking&rdquo motion back and forth about its long axis, as well, which occurs over a longer period than the short axis wobble. (The technical term for this rocking motion is &ldquonon-principal axis rotation.&rdquo)

Structure

Apophis is classified as an S-type, or stony-type asteroid, made up of silicate (or rocky) materials and a mixture of metallic nickel and iron. Radar images suggest it is elongated and possibly has two lobes, making it look something like a peanut. Much more will be learned about this asteroid's structure following its close flyby of Earth in 2029.

Formation

Like all asteroids, Apophis is a remnant from the early formation of our solar system about 4.6 billion years ago. It originated in the main asteroid belt between Mars and Jupiter. Over millions of years, its orbit was changed primarily by the gravitational influence of large planets like Jupiter so that it now orbits the Sun closer to Earth. As a result, Apophis is classified as a near-Earth asteroid, as opposed to a main-belt asteroid.

Surface

There are no high-resolution images of the surface of asteroid Apophis, but it is likely similar to surfaces of other stony-type asteroids like Itokawa, the first asteroid from which samples were captured and brought to Earth for analysis.


Apophis asteroid, nicknamed 'God of Chaos,' is speeding up

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An asteroid that has been nicknamed after the Egyptian God of Chaos is speeding up, scientists recently revealed.

Scientifically known as 99942 Apophis, the massive, 1,120-foot-wide space rock will fly within 23,441 miles above Earth's surface on April 13, 2029, as well as in 2036. However, it's the space rock's flyby in 2068 that may be impacted by the slight alteration in its previously predicted orbit, due to the Yarkovsky effect, that has scientists talking.

“We have known for some time that an impact with Earth is not possible during the 2029 close approach,” said one of the study's authors, University of Hawaiʻi Institute for Astronomy astronomer Dave Tholen, in a statement. “The new observations we obtained with the Subaru telescope earlier this year were good enough to reveal the Yarkovsky acceleration of Apophis, and they show that the asteroid is drifting away from a purely gravitational orbit by about 170 meters per year, which is enough to keep the 2068 impact scenario in play.”

Asteroid Apophis was discovered on June 19, 2004. (UH/IA)

Tholen, who has been tracking Apophis since his team discovered it in 2004, presented the findings at the 2020 virtual meeting of the Division for Planetary Sciences of the American Astronomical Society. His comments can be found in this video at the 22-minute mark.

The Yarkovsky effect, or Yarkovsky acceleration, is caused by the sun heating the space rock unevenly, resulting in a "process that slightly changes the orbit of the asteroid," the statement added.

The chances of 99942 Apophis impacting Earth are still low -- previously calculated at about 1 in 150,000 by the Center for Near-Earth Studies -- but it's enough to give scientists a pause for concern.

In 2019, SpaceX and Tesla CEO Elon Musk said that despite the asteroid's "great name" he wouldn't worry about this "particular" asteroid.

He cautioned, however, that a "big rock will hit Earth eventually and we have no defense for it."

The size and proximity to Earth of 99942 Apophis make it a near-Earth object (NEO), and in this case, a "potentially hazardous" one.

"Potentially hazardous" NEOs are defined as space objects that come within 0.05 astronomical units and measure more than 460 feet in diameter, according to NASA. According to a 2018 report put together by Planetary.org, there are more than 18,000 NEOs.

NASA unveiled a 20-page plan in 2018 that details the steps the U.S. should take to be better prepared for NEOs, such as asteroids and comets that come within 30 million miles of the planet.

A recent survey showed that Americans prefer a space program that focuses on potential asteroid impacts over sending humans back to the moon or to Mars.

NASA Administrator Jim Bridenstine said in April 2019 that an asteroid strike is not something to be taken lightly and is perhaps Earth's biggest threat.


Clues to ancient 15-mile-wide asteroid impact found in Western Australia

Tiny impact spherule from Duffer Formation, Australia. Image credit: Andrew Glikson et al. AN animation: Ade Ashford. Scientists have found evidence of a huge asteroid that struck the Earth early in its life with an impact larger than anything humans have experienced.

Tiny glass beads called spherules, found in northwestern Australia, were formed from vaporised material from the asteroid impact, said Dr. Andrew Glikson from The Australian National University (ANU).

“The impact would have triggered earthquakes orders of magnitude greater than terrestrial earthquakes, it would have caused huge tsunamis and would have made cliffs crumble,” said Dr. Glikson, from the ANU Planetary Institute and also Geoscience Australia.

“Material from the impact would have spread worldwide. These spherules were found in sea floor sediments that date from 3.46 billion years ago.”

The asteroid is the second oldest known to have hit the Earth and one of the largest.

Dr. Glikson said the asteroid would have been 20 to 30 kilometres across and would have created a crater hundreds of kilometers wide.

About 3.8 to 3.9 billion years ago the Moon was struck by numerous asteroids, which formed the giant craters, called maria [singular: mare], that are still visible from Earth.

“Exactly where this asteroid struck the Earth remains a mystery,” Dr. Glikson said. “Any craters from this time on Earth’s surface have been obliterated by volcanic activity and tectonic movements.”

Dr. Andrew Glikson. Image credit: Australian National University (ANU). Dr. Glikson and Dr. Arthur Hickman from Geological Survey of Western Australia found the glass beads in a drill core from Marble Bar, in northwestern Australia, in some of the oldest known sediments on Earth.

The sediment layer, which was originally on the ocean floor, was preserved between two volcanic layers, which enabled very precise dating of its origin.

Dr. Glikson has been searching for evidence of ancient impacts for more than 20 years and immediately suspected the glass beads originated from an asteroid strike.

Subsequent testing found the levels of elements such as platinum, nickel and chromium matched those in asteroids. There may have been many more similar impacts, for which the evidence has not been found, said Dr. Glikson.

“This is just the tip of the iceberg. We’ve only found evidence for 17 impacts older than 2.5 billion years, but there could have been hundreds.”

“Asteroid strikes this big result in major tectonic shifts and extensive magma flows. They could have significantly affected the way the Earth evolved.”

Dr. Glikson is lead author on a study published in the July 2016 issue of the journal Precambrian Research.


NASA tracking huge 'near-Earth' asteroid twice as big as Great Pyramid of Giza

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Space: 'Large UFO' appears to fly into the Sun

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The space rock has been classed as a Near-Earth Object (NEO) by the organisation. Any comet or asteroid within 1.3 astronomical units from the Sun fits into this category meaning it will not harm human life.

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According to reports, the asteroid is believed to be between 120m and 270m wide and between 394ft and 886ft tall.

The size of the gigantic space rock is almost twice as big as the iconic Egyptian landmark.

The asteroid will reportedly pass Earth at around 8am EST on September 6.

According to NASA, a NEO is a term used to describe "comets and asteroids that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth&rsquos neighbourhood".

NASA tracking giant asteroid (Image: Getty)

The asteroid twice the size of Great Pyramid (Image: Getty)

In relation to NEOs, the organisation says: &ldquoAs they orbit the Sun, NEOs can occasionally approach close to Earth.

&ldquoNote that a &lsquoclose&rsquo passage astronomically can be very far away in human terms: millions or even tens of millions of kilometres.&rdquo

In this particular case, NASA has ruled out any probability of impact with Earth and does not expect this to change.

There are, however, processes by which asteroids and comets can be shifted from their orbits towards us.

NASA tracking giant asteroid (Image: NASA)

Related articles

NASA said: &ldquoOccasionally, asteroids' orbital paths are influenced by the gravitational tug of planets, which cause their paths to alter.

&ldquoScientists believe stray asteroids or fragments from earlier collisions have slammed into Earth in the past, playing a major role in the evolution of our planet.&rdquo

A force known as the Yarkovsky effect can also cause an asteroid to veer off-course.

The effect occurs when a space rock is heated in direct sunlight and cools down to release radiation from its surface.

What is a close approach? (Image: Express)

NASA said: &ldquoThis radiation exerts a force on the asteroid, acting as a sort of mini-thruster that can slowly change the asteroid's direction over time.&rdquo

There is also the possibility of asteroids or fragmented asteroids, being redirected towards us after colliding with other space rocks.

According to Deborah Byrd, founder of EarthSky, one such collision could have resulted in the death of the dinosaurs some 65 million years ago.

She said: &ldquoOne fragment of that ancient smashup might have struck Earth 65 million years ago, triggering a mass extinction that wiped out the dinosaurs, according to astronomers.&rdquo

The Great Pyramid of Giza (Image: Getty)

But the asteroids listed on NASA&rsquos database of &ldquoEarth close approaches&rdquo are deemed safe and NASA&rsquos tracking systems have ruled out all possibility of danger.

NASA said: &ldquoBecause of the ongoing search efforts to find nearly all the large NEOs, objects will occasionally be found to be on very close Earth approaching trajectories.

&ldquoGreat care must then be taken to verify any Earth collision predictions that are made.

The asteroid will pass Earth in September (Image: Getty)

&ldquoGiven the extremely unlikely nature of such a collision, almost all of these predictions will turn out to be false alarms.

&ldquoHowever, if an object is verified to be on an Earth colliding trajectory, it seems likely that this collision possibility will be known several years prior to the actual event.&rdquo

Astronomers are believed to be currently tracking nearly 2,000 asteroids, comets and other objects.


Did Asteroid Baptistina Kill The Dinosaurs? Think Other WISE…

Once upon a time, about 65 million years ago, scientists hypothesize a sizable asteroid crashed into Earth and contributed to the extinction of the dinosaurs. The evidence is a 150-kilometer-wide crater located just off the Yucatan peninsula and legend has it the 10-kilometer-wide asteroid was a fragment of a larger parent – Baptistina. Now, thanks to observations by NASA’s Wide-field Infrared Survey Explorer (WISE), we just might have to re-think that theory.

While there’s almost absolutely no doubt an asteroid crash was responsible for a cataclysmic climate change, science has never been particularly sure of what asteroid caused it. A visible-light study done by terrestrial telescopes in 2007 pointed a finger at a huge asteroid known as Baptistina. The conjecture was that about 160 million years ago, it collided with another main belt asteroid and sent pieces flying. Even though it was plausible, the theory was quickly challenged and now infra-red evidence from WISE may finally lay this family of asteroids to rest.

“As a result of the WISE science team’s investigation, the demise of the dinosaurs remains in the cold case files,” said Lindley Johnson, program executive for the Near Earth Object (NEO) Observation Program at NASA Headquarters in Washington. “The original calculations with visible light estimated the size and reflectivity of the Baptistina family members, leading to estimates of their age, but we now know those estimates were off. With infrared light, WISE was able to get a more accurate estimate, which throws the timing of the Baptistina theory into question.”

For over a year, WISE took an infra-red survey of the entire sky and asteroid-hunting portion of the mission, called NEOWISE, cataloged 157,000 members – discovering an additional 33,000 new ones. By utilizing the more accurate infra-red data, the team examined 1,056 members of the Baptistina family and discovered its break-up was closer to 80 million years ago – less than half the time previously suggested. By better knowing their size and reflectivity, researchers are able to calculate how long it would take for Baptistina members to reach their current position. The results show that in order for this particular asteroid to have caused an extinction level event, that it would have had to have impacted Earth much sooner… like about 15 million years.

“This doesn’t give the remnants from the collision very much time to move into a resonance spot, and get flung down to Earth 65 million years ago,” said Amy Mainzer, a study co-author and the principal investigator of NEOWISE at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena. Calif. “This process is thought to normally take many tens of millions of years.”

Like bouncing a super ball off the walls, resonance spots can jettison asteroids out of the main belt. This means a dinosaur-killing Baptistina event isn’t likely, but other asteroid families in NEOWISE study show similar reflective properties and one day we may be able to locate a responsible party.

“We are working on creating an asteroid family tree of sorts,” said Joseph Masiero, the lead author of the study. “We are starting to refine our picture of how the asteroids in the main belt smashed together and mixed up.”


Huge Asteroid Crater in Antarctica

Image of Antarctica captured by Galileo. Image credit: NASA. Click to enlarge
The asteroid impact that killed the dinosaurs 65 million years ago was big, but geologists have found a new asteroid crater that’s even bigger: in Antarctica. This 482 km (300 mile) crater was discovered using NASA’s GRACE satellites, which can detect the gravity fluctuations beneath Antarctica’s ice sheets. This meteor was probably 48 km (30 miles) across and might have struck 250 million years ago – the time of the Permian-Triassic extinction, when almost all the animals on Earth died out.

Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs — an impact that they believe caused the biggest mass extinction in Earth’s history.

The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years — the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.

Its size and location — in the Wilkes Land region of East Antarctica, south of Australia — also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.

Scientists believe that the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence. The Wilkes Land crater is more than twice the size of the Chicxulub crater in the Yucatan peninsula, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago. The Chicxulub meteor is thought to have been 6 miles wide, while the Wilkes Land meteor could have been up to 30 miles wide — four or five times wider.

“This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time,” said Ralph von Frese, a professor of geological sciences at Ohio State University.

He and Laramie Potts, a postdoctoral researcher in geological sciences, led the team that discovered the crater. They collaborated with other Ohio State and NASA scientists, as well as international partners from Russia and Korea. They reported their preliminary results in a recent poster session at the American Geophysical Union Joint Assembly meeting in Baltimore.

The scientists used gravity fluctuations measured by NASA’s GRACE satellites to peer beneath Antarctica’s icy surface, and found a 200-mile-wide plug of mantle material — a mass concentration, or “mascon” in geological parlance — that had risen up into the Earth’s crust.

Mascons are the planetary equivalent of a bump on the head. They form where large objects slam into a planet’s surface. Upon impact, the denser mantle layer bounces up into the overlying crust, which holds it in place beneath the crater.

When the scientists overlaid their gravity image with airborne radar images of the ground beneath the ice, they found the mascon perfectly centered inside a circular ridge some 300 miles wide — a crater easily large enough to hold the state of Ohio.

Taken alone, the ridge structure wouldn’t prove anything. But to von Frese, the addition of the mascon means “impact.” Years of studying similar impacts on the moon have honed his ability to find them.

“If I saw this same mascon signal on the moon, I’d expect to see a crater around it,” he said. “And when we looked at the ice-probing airborne radar, there it was.”

“There are at least 20 impact craters this size or larger on the moon, so it is not surprising to find one here,” he continued. “The active geology of the Earth likely scrubbed its surface clean of many more.”

He and Potts admitted that such signals are open to interpretation. Even with radar and gravity measurements, scientists are only just beginning to understand what’s happening inside the planet. Still, von Frese said that the circumstances of the radar and mascon signals support their interpretation.

“We compared two completely different data sets taken under different conditions, and they matched up,” he said.

To estimate when the impact took place, the scientists took a clue from the fact that the mascon is still visible.

“On the moon, you can look at craters, and the mascons are still there,” von Frese said. “But on Earth, it’s unusual to find mascons, because the planet is geologically active. The interior eventually recovers and the mascon goes away.” He cited the very large and much older Vredefort crater in South Africa that must have once had a mascon, but no evidence of it can be seen now.

“Based on what we know about the geologic history of the region, this Wilkes Land mascon formed recently by geologic standards — probably about 250 million years ago,” he said. “In another half a billion years, the Wilkes Land mascon will probably disappear, too.”

Approximately 100 million years ago, Australia split from the ancient Gondwana supercontinent and began drifting north, pushed away by the expansion of a rift valley into the eastern Indian Ocean. The rift cuts directly through the crater, so the impact may have helped the rift to form, von Frese said.

But the more immediate effects of the impact would have devastated life on Earth.

“All the environmental changes that would have resulted from the impact would have created a highly caustic environment that was really hard to endure. So it makes sense that a lot of life went extinct at that time,” he said.

He and Potts would like to go to Antarctica to confirm the finding. The best evidence would come from the rocks within the crater. Since the cost of drilling through more than a mile of ice to reach these rocks directly is prohibitive, they want to hunt for them at the base of the ice along the coast where the ice streams are pushing scoured rock into the sea. Airborne gravity and magnetic surveys would also be very useful for testing their interpretation of the satellite data, they said.

NSF and NASA funded this work. Collaborators included Stuart Wells and Orlando Hernandez, graduate students in geological sciences at Ohio State Luis Gaya-Piqu??bf? and Hyung Rae Kim, both of NASA’s Goddard Space Flight Center Alexander Golynsky of the All-Russia Research Institute for Geology and Mineral Resources of the World Ocean and Jeong Woo Kim and Jong Sun Hwang, both of Sejong University in Korea.


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