Astronomy

Accuracy of predicting an asteroid strike in 1987

Accuracy of predicting an asteroid strike in 1987

Good People,

I am writing a short story, and I wanted to include a section wherein a family is told that an asteroid is going to strike their home. The thing is, I would like to set the story in 1987, but I'm not sure if there was the capability of that kind of prediction back then. To be honest, I'm not even sure that kind of accuracy is possible now! But I will allow myself some creative freedom in that area, but I don't want to stretch it so much that someone would keep thinking to themselves, "Really, in 1987 they could predict that?" Would such a thing have been possible then? If not then, what about sometime in the 90s?

While I have your eyes, is there a specific size that an asteroid would have to be in order to just destroy one home (or a couple on the side of the home).

Thank you for any insight and info! I appreciate the resources here. I did some digging around before asking this question: nothing seemed to be particular to my frame of reference. If it exists, please let me know.


There are problems with this:

What happens when an asteroid hits the atmosphere

The asteroid will be travelling fast, more than 10 km per second. In front of it the atmosphere will be compressed and heat up, this causes the "meteor" (a streak of light in the sky). It also causes puts a lot of stress on the asteroid.

If the asteroid is very small (sand grain to pebble sized), it gets destroyed completely. If it is larger it can explosively break up. But several chunks can continue at terminal velocity (ie no faster than a stone dropped from a high building) and don't form craters. These chunks can later be picked up as meteorites.

If the body is very large it can survive the atmosphere, hit the Earth at hypervelocity (several km/s) and form a larger crater.

If you want the body to survive, but only form a small crater you need either a very strong body (a solid iron asteroid) or an odd set of events, such as at the Carancas impact. In these cases a small crater or crater field can form. The size of the impactor is about 50cm.

Detecting and forecasting impact

A 50cm asteroid is not currently detectable until very close to the Earth. We have seen asteroids that are a couple of metres across, but they need to be close to the Earth (and we need to be lucky).

In 2008 we did get lucky and saw a small object before it hit Earth. In that case we had a few hours of observations and by about an hour before impact we were able to narrow the impact zone down to "Northern Sudan". Now (North) Sudan is huge, an area about 3 times the size of Texas. And in 2008 we already had an active Near Earth Object search program, something that we did not have in 1987. Even if the asteroid was noticed by lucky amateur, before the internet it would have been very hard to coordinate the observations needed even to predict "Northern Sudan". This meteorite exploded at altitude and did not form a crater.

To conclude, most meteorites will not take out a single house and leave neighbours standing. Such meteorites that could are not currently detectable before impact. Even with current technology and lots of luck we could not predict the impact location better than "somewhere between New Mexico and Florida" but not a single address.

There are other things that can destroy a house, perhaps a sinkhole? Perhaps these are more predictable (with luck) than an asteroid impact.


Truth is stranger than fiction: an asteroid was observed less than 24 hours before striking Earth in 2008. JPL predicted the time of the collision to within 15 seconds, but the meteor exploded in the upper atmosphere, and the fragments were scattered over many kilometers of Sudanese desert.


Younger Dryas impact hypothesis

The Younger Dryas impact hypothesis (YDIH) or Clovis comet hypothesis posits that fragments of a large (more than 4 kilometers in diameter), disintegrating asteroid or comet struck North America, South America, Europe, and western Asia around 12,800 years ago. [1] [2] Multiple airbursts/impacts produced the Younger Dryas (YD) boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at more than 50 sites across about 50 million km 2 of Earth’s surface. Some scientists have proposed that this event triggered extensive biomass burning, a brief impact winter and the Younger Dryas abrupt climate change, contributed to extinctions of late Pleistocene megafauna, and resulted in the end of the Clovis culture. [3]


Billy Meier Prediction #1 – Pacific Tsunami Prophecy

At the end of 2005, Oregon State University researchers published a report noting that Congress was working on legislation to give NOAA $35 million per year to improve tsunami warning systems and disaster planning. Researchers noted that the increased interest in tsunami planning was due to the 2004 Indonesia tsunami that killed more than 275,000 people.

In 2008, Michael Horn started traveling around the Internet, telling people that a Billy Meier prediction, allegedly provided prior to the OSU 2005 warning, mirrored the OSU prediction. This is a standard Michael Horn tactic – find some publication about a dire warning, and then distribute information to any “believer” website that will publish it, that Meier had made the prediction before the warning published.

Unfortunately for Horn, it’s very difficult for a non-technical person to fake publication dates. Even his own website has the publication date for this claim as 2008. Every Pro-Meier website out there also lists a publication date of this claim on or after 2008, when Horn began distributing the claim.

The reality is that the only floods mentioned in the 1958 predictions are vague references to “monstrous flooding”, without any dates or specific regions mentioned at all, certainly not the Pacific Northeast.

When a tsunami does strike the Pacific Northeast, Horn will likely instantly claim that Meier “accurately” predicted it, failing to mention that Meier’s “prediction” came in 2008, four years after the tsunami warning system was put in place in 2004.

Billy Meier Prediction #2 – Asteroid Apophis

One of the best investigations of a Billy Meier prophecy came from Stuart Robbins of the Bad Science blog, who decided to do a thorough analysis of Michael Horn’s claim that Meier had predicted the asteroid Apophis will strike Earth in 2036.

The first thing Stuart noted was the fact that Meier’s actual prediction dated in 1981 made no mention of the Apophis asteroid, or even a date for the event, but only mentioned that a “red meteor” would wreak havoc on Earth. Nothing more.

Interestingly enough, the pattern with Asteroid Apophis follows the same pattern as the Pacific Northwest Tsunami warning. In 2004, the asteroid Apophis was officially discovered and publicly announced. In 2008 (a busy year for Horn), Meier suddenly releases “Contact Report #471”, where Meier claims having a conversation with Plejaran Ptaah, and finally specifically mentions astronomical data related to Apophis. Stuart noted the discrepancy as follows:

“Okay, so remember the timeline here: 1981 was the first mention, 2002 no new information, 2004 Apophis is found and its orbit calculated and all this other stuff, and then, FOUR YEARS LATER, Meier very directly links his red meteor with the astronomical data of Apophis, though we don’t have it by name. There was nothing connecting the two before, and Apophis isn’t exactly red, but now he’s put the red meteor together with the dates of Apophis.”

As I said, Meier and Horn are a slippery pair.

Finally, four contact reports later, Meier specifically claims that Apophis is the “Red Meteor”. This tactic is what Stuart explains as “retrodiction” – a technique that prophecy scammers constantly use.

Prediction [is] where you’re saying something will happen before it does. Retrodiction is the opposite, where you say something was going to happen after it already did, or you said something vague and then when something specific happens, you claim that vague thing was the specific happening.

Stuart further noted that Meier’s original prophecy described a “meteor”. Apophis is an asteroid. In his final analysis, Robbins concludes that until better evidence arises, this is clearly “not a valid prediction”.

Coincidentally, NASA’s scientific findings make Meier’s so-called prophecy even less likely. Initial estimates in 2007 put the pass at 49 million km (30.5 million miles) from Earth. Updated calculations in 2013 put Apophis even further away.

Billy Meier Prediction #3 – Jupiter Moons

An IIG researcher conducted a full investigation in 2004 surrounding Meier’s various predictions from throughout his 115th Contact writings. The investigator found the following revealing facts about those so-called prophecies:

– Meier’s predictions in 1978 about the details of Jupiter were not predicted, but actually drawn from information reported publicly after Pioneer 10 and Pioneer 11 passed by Jupiter in the early 1970s. Scientists did not discover that Jupiter’s ring was made of small particles in 1995 as Horn claimed. That information was published in 1979.

– The investigator proved that Meier had drawn his “prediction” directly out of newspaper and magazine reports in 1979, because one of his predictions regarding Amalthea, the innermost moon, perfectly matched the incorrect information (that the moon was approximately 200 km long) published in the 1979 newspaper articles. (The moon was later determined by scientists to actually be 250-270 km long).

– Meier had copied from the media claims in 1979 that speculated (incorrectly) that Jupiter’s moon Io contained water. Meier wrote, “”the moon, Io, once was totally covered with water”. Later scientific findings revealed the truth – Io contains little to no water.

– Other predictions that the IIG researcher noted Meier as getting completely wrong (usually because he copied incorrect information from 1979 media sources) or the researcher proved Meier had obtained correct information from earlier media sources were related to facts like Io’s volcano eruptions, Io’s Plasma Torus, the rings of Jupiter, and much more. You can read the full, detailed, thorough report at the IIG West website.

The IIG researcher finally concluded:

“The fact is, the more I researched the predictive information in Billy Meier’s Contacts, the more likely it seemed that Meier copied his information from widely-available news sources.”

Other False Prophecies of Billy Meier

IIG (Independent Investigations Group) has done a tremendous job on the Meier case. Further prophecies proved as incorrect by the group included the claim that four heads of state would die within seven days of each other, signaling the coming of World War III.

Michael Horn (not Meier or FIGU) claimed the prophecy came true in December 2006 when four heads of state died in a row. December 2008 came and went without World War III. So much for that one.

Meier predicted in Contact 251, Part 2 that a French nuclear reactor near Lyon would have an accident and that the plant would be promptly shut down. Michael Horn claimed this prophecy was proven true in August 12, 2003.

IIG showed that the actual news articles referencing the Bugey nuclear power station near Lyon, France were actually referencing the danger of the nuclear plant shutting down in the midst of a heat wave, when citizens of the country were so desperately in need of its power. The facility never had an accident, and was never shut down due to any accident. Another false prophecy.

Researcher Royce Myers, III was able to prove on UFO Watchdog that a picture Billy claimed he took when he traveled back in time to the land of the dinosaurs was in fact a fuzzy, close-up of a painting by Czech artist Zdenek Burian, which appeared in the book Life Before Man.

I wonder if the Meier folks are paying Zdenek royalties for misrepresenting his work?

A final analysis I would like to highlight was actually conducted by my good friend who went by the name of “Zep Tepi” on Reality Uncovered forums. In a discussion there, Zep pointedly asked Michael Horn about the Meier prediction which claimed that Paris would be destroyed and burned down. In an update on his website at a newsletter link called ‘nov05.htm’ (which Horn has subsequently deleted), Horn claimed that Meier’s “Paris will be destroyed” prophecy came true following the Paris riots of October 2005.

During those riots, nearly 9,000 vehicles were torched, nearly 3,000 people were arrested, and 126 police officers were injured. Zep pointedly asked Michael Horn how he could describe such an event – which was admittedly destructive – as the destruction of Paris predicted by Meier.

Horn’s only answer was to state that prophecies could be altered if people make “course corrections” to alter the probable outcomes. He failed to specifically explain why he had claimed Meier’s prophecy had come true, when it clearly hadn’t. The fact that he also deleted that page from his website speaks volumes as well.


Pat Robertson predicted that an asteroid would blow up the earth.

While speaking about the 𠇎nd times” for the world after Donald Trump is re-elected, he also said that more than five years will pass between the end of the election and the deadly asteroid’s arrival. He predicted there will essentially be a civil war after the election including two assassination attempts on President Trump. 

He also mentioned that a war against Israel will end only when God intervenes. “God is going to bring a period of great peace,’’ he said. The episode ended with a moment of prayer.


End Of The World Asteroid Hurtling Toward Earth, Would Impact With The Force Of 3 Billion Nukes

A giant killer asteroid estimated to be as big as 10 miles wide is heading toward Earth, astronomers are saying. It is moving at such a high rate of speed that its impact, if it were to hit the Earth, would deliver the destructive force of 3 billion nuclear bombs.

The Daily Star reported this week that a massive killer asteroid, one that could be as big as 10 miles across, is headed in Earth's direction, but astronomers have yet to pinpoint its exact trajectory through the Solar System, so estimating if it will actually hit the Earth cannot be done with accuracy. The asteroid, designated 2009ES, is being studiously tracked by the world's astronomers, just in case its orbital path becomes altered and sends it on a collision course with Earth.

The giant asteroid, which was first spotted in 2009 (hence the numerical part of its designation), was detected by astronomer Zhao Haibin using the large telescope at the Purple Mountain Observatory in Nanjing, China. Images of asteroid 2009ES, which got its name from the Minor Planet Center, were captured by the 1.2-meter Schmidt telescope camera just last week.

"With the help of our images," Haibin said, "astronomers across the globe have a more accurate moving trajectory of the asteroid."

The Chinese Academy of Science, according to AOL News, estimates that the potentially killer asteroid, as derived from its current path, will pass to within 18.8 Lunar Distances (the distance from the center of the Earth to the center of the Moon) of Earth.

Being able to plot the course of the object -- one of 1,640 near-Earth asteroids, called "minor bodies," that are moving toward Earth -- could become very important should the giant asteroid be found to be coming uncomfortably close to the Earth. A slight deviation in its path could then send the space rock heading directly toward the Earth. Given the size of 2009ES, it is believed the impact would cause an extinction event. Basically, the end of the world.

In fact, it is estimated that an impact by 2009ES would produce the energy equivalent of 3 billion nuclear bombs. According to the Daily Star, the event would render humans extinct, producing an effect equivalent to the event that contributed to the extinction of the dinosaurs and created the Chicxulub Crater off the Yucatan Peninsula of Mexico.

But, as of now, NASA reports that there are no known asteroids in danger of hitting the Earth at least for a few hundred years. The space agency felt compelled to release a statement in August 2015 to assuage public fears of an impending asteroid impact being generated by doomsayer blogs and end-of-the-world forecasting websites. "NASA knows of no asteroid or comet currently on a collision course with Earth," the statement read, "so the probability of a major collision is quite small. In fact, as best as we can tell, no large object is likely to strike the Earth any time in the next several hundred years."

NASA, the European Space Agency, and other governmental and private industry interests are developing contingency plans to better detect and track potentially hazardous asteroids. Some are also developing methods by which a catastrophic event-producing asteroid might be diverted or redirected (known as "asteroid impact avoidance") from a potential collision with Earth. Such "impact avoidance" methods include nuclear detonation to deflect (as opposed to pulverizing the asteroid into numerous fragments, which could prove far more dangerous to the Earth than one solid projectile), ramming the object, focusing solar energy to produce the Yarkovsky Effect (solar radiation would produce a deviation of course), installing or attaching a rocket engine to the object, and placing an object of sufficient mass to gravitationally pull the target asteroid off its path (called a gravity tractor).

2009ES isn't the only near-Earth asteroid we will have to watch the skies for in the coming years. As Inquisitr reported in early August, a killer asteroid called Bennu, which doomsayers were predicting was on a trajectory with Earth, might actually impact the planet about 150 years from now. Even so, Bennu is nowhere near the size of 2009ES, measuring at just 1,650 feet wide (500 meters).

As reported by Inquistr, the same can be said of Apophis, an asteroid that will make a near-miss pass by the Earth in 2029. Just 325 meters (1,066 feet, or almost four football fields) wide, asteroid Apophis, according to the most recent calculations (per the Minor Planet Center), will miss Earth by less than 25,000 miles.


Earth is safe from asteroid Apophis for the next 100 years

During the asteroid Apophis’ most recent flyby in early March, astronomers were busy taking observations of this infamous space rock. Later calculations let NASA scientists announce on March 26, 2021, that Earth is safe from an impact with the relatively large asteroid for at least the next 100 years. Radar observations taken at NASA’s Goldstone Deep Space Communications Complex in California and the Green Bank Observatory in West Virginia have officially ruled out an impact in 2068, the only year out of the next 100 that previously showed a slight risk. Earlier observations had ruled out impacts during the upcoming 2029 and 2036 flybys.

Davide Farnocchia of NASA’s Center for Near-Earth Object Studies said:

A 2068 impact is not in the realm of possibility anymore, and our calculations don’t show any impact risk for at least the next 100 years.

This new analysis means that Apophis is no longer on the Sentry Impact Risk Table, which is a list of objects that pass so close by Earth that astronomers have not yet been able to rule out a possible strike.

Apophis is a near-Earth asteroid with a relatively large size (it is about 1,100 feet – or 335 meters – wide). It gained notoriety in 2004 when early observations suggested it might strike Earth in 2029. Though it will come breathtakingly close to Earth in 2029, a strike was subsequently ruled out. Apophis should pass on Friday 13, April 2029 at a nominal distance of 19,662 miles (31,643 km) from Earth’s surface. That’s in contrast to the moon’s average distance of about a quarter-million miles (380,000 km).

These images show asteroid Apophis during 3 days of its flyby on March 8, 9 and 10, 2021. Radio antennas at the Deep Space Network’s Goldstone complex in California and the Green Bank Telescope in West Virginia worked together to acquire these images. The asteroid was 10.6 million miles (17 million km) away, and each pixel has a resolution of 127 feet (39 meters). Image via NASA/ JPL-Caltech/ NSF/ AUI/ GBO.

In early March, all eyes turned toward Apophis as the asteroid made a relatively close sweep (though not nearly as close as in 2029) to our planet on March 6. The Goldstone Deep Space Communications Complex tracked the asteroid for about two weeks around closest approach. Researchers at the Green Bank Telescope took observations, coordinating with Goldstone, because the use of these two telescopes together allows the data to be sharper. The coordination between the two telescopes meant that Goldstone was transmitting data while Green Bank was receiving, performing what is known as a bistatic experiment that doubled the strength of the received signal. Marina Brozovic of NASA’s Jet Propulsion Laboratory explained:

Apophis made a recent close approach with Earth, it was still nearly 10.6 million miles (17 million kilometers) away. Even so, we were able to acquire incredibly precise information about its distance to an accuracy of about 150 meters (490 feet). This campaign not only helped us rule out any impact risk, it set us up for a wonderful science opportunity.

The images seen at top are the product of the collaboration. Brozovic went on to describe the excellent quality achieved through the collaboration, which she called:

…a remarkable resolution, considering the asteroid was 17 million kilometers away, or about 44 times the Earth-moon distance. If we had binoculars as powerful as this radar, we would be able to sit in Los Angeles and read a dinner menu at a restaurant in New York.

Further analysis of the radar data collected in early March should help astronomers learn what Apophis’ shape is. Previous observations suggest that the asteroid is peanut-shaped – also described as bilobed, or having two lobes – a common shape for near-Earth asteroids.

In addition, astronomers hope to learn more about the asteroid’s rotation rate and spin state, which might tell them what effects could occur on Apophis during its very close flyby in 2029. As the asteroid encounters Earth’s gravitational field in 2029, asteroid quakes could result on Apophis.

The Virtual Telescope Project, based in Rome, Italy, captured asteroid (99942) Apophis on March 2, 2021. The asteroid shows as a dot – while the stars around it show as streaks – because the telescope was tracking the asteroid’s motion. It is moving through space with respect to Earth at 4.658 km/sec (2.894 miles/sec). Image via Virtual Telescope.

Astronomers are also planning to study asteroid Apophis using NASA’s NEOWISE infrared space telescope in April 2021. This is the same telescope that discovered 2020’s favorite comet, Comet NEOWISE, which has now faded from view.

Astronomers in Hawaii recently studied how Yarkovsky acceleration, or pushes due to sunlight, would change Apophis’ orbit. In some instances, acceleration – a change in an object’s speed and direction through space – can help avoid a collision. Studies of Yarkovsky acceleration as related to asteroid Apophis suggest this is the case for this asteroid. Previous calculations (made in 2016) had already all but ruled out the probability of an impact in 2068. The chance of an impact was seen in 2016 as vanishingly small, at just 1 in 150,000 odds of impact, or a 99.99933% chance the asteroid would miss the Earth.

The more recent observations, first discussed in October 2020 and updated again in early 2021, showed a decreasing risk.

Orbit of asteroid Apophis (pink) in contrast to the orbit of Earth (blue). The yellow dot represents the sun. Apophis takes 323.6 days to orbit the sun. Earth takes 365.3 days. Thus this asteroid is a fairly frequent visitor to our region of space. Image via Phoenix7777/ Wikimedia Commons.

Astronomer Dave Tholen and colleagues suggest that Apophis is drifting more than 500 feet (about 170 meters) per year from its expected position in its orbit. These observations aren’t easy to obtain and analyze. Factors such as the asteroid’s distance at the time of observation, its composition, its shape and its surface features all affect the outcome.

Apophis is, of course, not the only near-Earth asteroid. In recent years, astronomers have been able to find and track many tiny asteroids sweeping near Earth. For example, on September 24, 2020, asteroid 2020 SW swept even closer to us than our meteorological and television satellites as well as other geostationary satellites, which orbit our planet at some 22,300 miles (35,900 km) from Earth’s surface. Asteroid 2020 SW came within about 7% of the Earth-moon distance. But asteroid 2020 SW is estimated to be only about 14 to 32 feet (about 4.5 to 10 meters) in diameter. That’s very small in contrast to asteroid Apophis.

This animation shows the distance between the Apophis asteroid and Earth at the time of the asteroid’s closest approach in 2029. The blue dots are manmade satellites orbiting our planet, and the pink represents the International Space Station. Image via NASA/ JPL-Caltech.

The 2029 pass of asteroid Apophis. The April 13, 2029, encounter of Apophis with Earth will be extremely close. At its closest in 2029, Apophis will sweep at about 10% of the Earth-moon distance. That’s very close for a space rock over 1,115 ft (340 meters) across! Lance Benner of NASA/JPL commented:

This will be the closest approach by something this large currently known. (In 2029) Apophis will be visible to the unaided eye for several hours, and Earth tides will probably change its spin state.

Friday, April 13, 2029, will be a showtime for asteroid Apophis, for the general public and astronomers alike. Apophis will come so close that it’ll be visible to the unaided eye alone something that almost never happens with asteroids. According to NASA, Apophis will first become visible in the Southern Hemisphere and will look like a speck of light moving across Australia during this close encounter. It will be over the Atlantic Ocean at its closest approach to Earth. It will move so fast that it crosses the Atlantic in just an hour, and will have crossed the U.S. in the late afternoon/early evening within the next hour. Calculations indicate that Apophis will reach a visual magnitude of 3.1 during this approach, comparable to the stars in the Little Dipper. In 2029, Apophis is expected to be visible to the unaided eye from some areas of Australia, western Asia, Africa, and Europe.

Like many other asteroids, Apophis has been classified as a potentially hazardous asteroid by the International Astronomical Union’s Minor Planet Center. That just means it’s an asteroid whose orbit brings it close to Earth on occasion, which is large enough to cause “significant regional damage” in the event of an impact. A survey by the NEOWISE spacecraft in 2012 suggested that there are 4,700 ± 1,500 potentially hazardous asteroids with a diameter greater than 100 meters.

According to some estimates, an asteroid the size of Apophis can be expected to strike Earth about every 80,000 years.

As a result of the extremely close approach of April 2029, it is expected that perturbations caused by Earth’s gravity will change Apophis’ orbit from the Aten to the Apollo class. Image via Marco Polo/ Wikimedia Commons.

Bottom line: Observations of asteroid Apophis in early March enabled astronomers to conclude that Apophis has no chance of impacting with Earth in the next 100 years.


Study of ancient fish suggests Chicxulub asteroid strike warmed planet for 100,000 years

Artistic rendition of the Chicxulub impactor striking ancient Earth. Credit: Public Domain

A small team of researchers from the U.S. and Tunisia has found evidence that suggests a huge asteroid that struck the Earth approximately 66 million years ago caused the planet to warm up for approximately 100,000 years. In their paper published in the journal Science, the group describes their study of oxygen ratios in ancient fish bones and what it revealed.

Prior research has shown that approximately 66 million years ago, a massive asteroid struck the Earth at a point near what is now Chicxulub, Mexico. Other studies have suggested the sudden change in climate that resulted is what caused the dinosaurs to go extinct. The belief has been that the smoke and particles thrust into the atmosphere blocked out the sun causing the planet to cool for a long period of time. In this new effort, the researchers suggest the cooling period likely was shorter than thought and that it was followed by a lengthy hot spell. The researchers came to this conclusion by studying the bones and teeth of ancient fish.

The fish remains were sifted from sediment samples collected at a site in El Kef, Tunisia. During the time before and long after the asteroid strike, the area was covered by the Tethys Sea. The researchers looked at oxygen ratios in the fish remains as a means of determining the temperature of the water at the time that the fish died. Collecting samples from different layers allowed for building a temperature timeline that began before the asteroid strike and lasting hundreds of thousands of years thereafter. In looking at their timeline the group found that sea temperatures had risen approximately 5°C not long after the asteroid struck and had stayed at that temperature for approximately 100,000 years.

The researchers suggest the strike by the asteroid very likely released a lot of carbon dioxide into the atmosphere because the ground area where it struck was rich in carbonates. The strike very likely would have also ignited large long-burning forest fires which would have also released a lot of carbon into the air. The evidence suggests that the cooling after the impact was short-lived as massive amounts of carbon dioxide were released into the atmosphere setting off global warming.

The researchers note that a lot more work will need to be done to confirm their findings. Another site will have to be found with similar evidence, for example, to prove that the warming was not localized.

Abstract
Greenhouse warming is a predicted consequence of the Chicxulub impact, but supporting data are sparse. This shortcoming compromises understanding of the impact's effects, and it has persisted due to an absence of sections that both contain suitable material for traditional carbonate-based or organic-based paleothermometry and are complete and expanded enough to resolve changes on short time scales. We address the problem by analyzing the oxygen isotopic composition of fish debris, phosphatic microfossils that are relatively resistant to diagenetic alteration, from the Global Stratotype Section and Point for the Cretaceous/Paleogene boundary at El Kef, Tunisia. We report an

1‰ decrease in δ 18 O values (

5°C warming) beginning at the boundary and spanning

100,000 years). The pattern found matches expectations for impact-initiated greenhouse warming.


What Are The Real Odds Of ‘Doomsday’ Asteroid Apophis Striking Earth In 2068?

450 meters long along its long axis, asteroid Apophis could release about 50 times the energy of the Tunguska blast: minuscule compared to the asteroid that wiped out the dinosaurs, but many times larger than even the most powerful atomic bomb detonated in history.

Will near-Earth asteroid Apophis strike us in 2068?

Generically, asteroids under

1 km in size are irregularly shaped, will rotate with respect to the . [+] Sun, and will move in elliptical orbits as dictated by the law of gravity, but can be perturbed by effects such as uneven solar heating or the gravitational influence of other solar system bodies. Potentially hazardous asteroid Apophis will be subject to all of these factors.

Despite widespread affirmative reports, the collision threat is likely negligible.

The animation depicts a mapping of the positions of known near-Earth objects (NEOs) at points in . [+] time over the past 20 years, and finishes with a map of all known asteroids as of January 2018. In order to accurately know the orbital characteristics of an asteroid (or any near-Earth object), its position and velocity must be measured at many different points over time.

Many observations, over long timescales, are required to precisely reveal an asteroid's trajectory.

Asteroid Apophis has been measured many times over the timespan of multiple years quite precisely, . [+] leading scientists to determine its orbit to a remarkable precision. Of course, additional effects, such as offgassing or gravitational encounters, have the potential to alter that orbit beyond mere Keplerian effects.

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Close gravitational encounters will also induce significant orbital changes.

Orbit of asteroid Apophis (pink) in contrast to the orbit of Earth (blue). The yellow dot represents . [+] the sun. Apophis takes 323.6 days to orbit the sun. Earth takes 365.3 days, but the April, 2029 encounter will dramatically change Apophis's orbit thereafter, where it will now take more than one Earth-year to complete a revolution about the Sun.

Phoenix7777/ Wikimedia Commons

Finally, solar heating will lead to volatile offgassing, accelerating asteroids with shape irregularities and rotational motions.

These two radar images (above and below) of asteroid Apophis show this large asteroid, about as . [+] large as the Empire State Building or the Eiffel Tower (but far more massive), rotating, tumbling, and with an irregular shape as it orbits the Sun.

Discovered in 2004, Apophis presently orbits the Sun every 323 days.

This five-exposure image shows asteroid Apophis (circled), with star trails seen in the background, . [+] as the asteroid (tracked) is moving relative to the background stars. Apophis was discovered in 2004, and will come very close to Earth three times this century: in 2029, 2036, and 2068.

D. Tholen, M. Micheli, G. Elliott, UH Institute for Astronomy

Initial measurements indicated Apophis had a 1-in-37 chance of impacting Earth in 2029.

When a potentially hazardous object is first measured, it will have a large cone of uncertainty to . [+] its impact parameters, leading to a moderate probability of collision with Earth if our planet's position is included in that cone. As the error ellipse narrows with improved precision, the calculated probability of striking Earth rises, only to fall again with Earth becomes excluded.

Lou Scheffer/public domain

That's untrue Apophis will miss Earth by 47,000 km (29,000 miles), with gravity drastically altering its orbit thereafter.

In April of 2029, asteroid Apophis will pass close to Earth, well within the orbit of the Moon and . [+] just a few Earth radii away from our world. Although the odds of a collision are negligible, the close encounter will drastically change the orbit of Apophis for its future close encounters, predicted to occur in 2036 and 2068.

Newly acquired Subaru telescope observations of Apophis revealed a surprise: the Yarkovsky effect.

When an asteroid or comet rotates with respect to the Sun, its Sun-facing side heats up while the . [+] opposite side cools down. The radiation coming from the different sides of the asteroid will have different magnitudes as a result of having different temperatures, causing an additional acceleration known as the Yarkovsky effect.

Graevemoore at English Wikipedia

Sunlight heated the rotating, irregular asteroid, causing unexpected accelerations.

Similar to the effects of sunlight on the nucleus of Comet 67P/Churyumov-Gerasimenko, the . [+] combination of solar heating, irregular shape, and rotation will cause an additional force to be exerted on asteroid Apophis, leading to alterations in its future orbit from the current predictions.

Prior odds of a 2068 collision were estimated at 1-in-150,000 new odds will require a reanalysis.

The close encounter between Apophis and Earth in 2029 will change the asteroid's trajectory, but the . [+] addition of the Yarkovsky effect means that the previous calculations of just a 1-in-150,000 chance of a collision in 2068 has been thrown into doubt. Additional, more accurate calculations will be needed to compute the new odds.

New satellite megaconstellations complicate ground-based observations near dusk and dawn: the most critical asteroid-tracking window.

Hypothetically, a collision would release

1200 Megatons of TNT of energy: enough to create a

Meteor (Barringer) crater, in the Arizona desert, is over 1.1 km (0.7 mi) in diameter, and . [+] represents only a 3-10 MegaTon release of energy. A 300-400 meter asteroid strike would release 10-100 times the energy asteroid Apophis is about 450 meters along its long axis, expected to release

1200 MT of energy if it strikes Earth.

However, with just 0.001% the mass of the legendary dinosaur-killing asteroid, it poses no extinction threat.

The asteroid redirect vehicle demonstrates the “gravity tractor” planetary defense technique on a . [+] hazardous-size asteroid. The gravity tractor method leverages the mass of the spacecraft to impart a gravitational force on the asteroid, slowly altering the asteroid’s trajectory. The science of planetary defense could literally prevent the catastrophe of the millennium from occurring on Earth.

Flyby spacecraft Deep Impact shows the flash that occurred when comet Tempel 1 ran over the . [+] spacecraft's impactor probe. It was taken by the flyby craft's High Resolution Instrument, Visual CCD camera (HRIV) over a period of about 40 seconds. A similar impact could potentially redirect a potentially hazardous asteroid, such as Apophis.

Paul Stephen Carlin / NASA / JPL

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less smile more.


The Asteroid that Almost Hit

Image credit: NASA
For a few hours on January 13, 2004, astronomers thought a 30-meter wide asteroid might hit the Earth. The asteroid AL00667 seemed to be on a direct course for the Northern Hemisphere, due to strike in less than two days.
A 30-meter asteroid is larger than a tennis court. An asteroid of this size would have broken up in the atmosphere, creating a one-megaton blast. If it exploded high enough, the asteroid probably wouldn’t have caused any damage. The shock wave from the blast would have become a sonic boom by the time it reached the ground. But an explosion lower in the atmosphere could have caused considerable damage.

Astronomers who knew about the asteroid believed an impact was not likely, but they couldn’t rule out the possibility, either. So they faced a dilemma – should they warn others about something that could end up passing us by?

President Bush was preparing to make a speech at NASA headquarters the next day. He planned to talk about sending a man back to the moon and then on to Mars, but news of an approaching asteroid may have caused him to make a very different kind of announcement.

The asteroid, which has since been renamed 2004 AS1, actually passed by at about 12 million kilometers away, or 32 times the Earth-moon distance. The asteroid also turned out to be 10 times larger than first thought (about 300 meters wide – or about the height of the Eiffel Tower).

Some recent news reports say that Clark Chapman, an astronomer with the Southwest Research Institute, was moments away from calling President Bush and warning him about the asteroid. Chapman, however, adamantly denies this.

“It is absurd to think that any of us in the loop would have called the White House,” states Chapman. “Hell, we wouldn’t even have gotten through. All I was thinking about was recommending to Don Yeomans, who is in charge of JPL’s [the Jet Propulsion Laboratory’s] Near Earth Object Program office, that he inform people at NASA. It would have had to go through several layers of hierarchy before it got to anyone who would have been in a position to go higher than NASA. And Yeomans says that he wouldn’t have acted on my advice, preferring to wait for further confirmation of the object.”

The difference between the initial estimates and the final result highlights the difficulty of monitoring the skies for small Near Earth Objects (NEOs). For 2004 AS1, astronomers knew the asteroid could be either big and far away, or small and close by.

“It’s rather like noticing something in the sky out of your car window that appears to be moving along with you,” explains Alan Harris of the Space Science Institute. “It could be a bird close to your car flying along at close to the same speed, or it could be a plane in the distance that only seems to be pacing your car.”

Over the next few weeks after January 13, the asteroid came even closer to Earth, but it still passed many times farther away than the moon. There are many asteroids that routinely pass much closer to the Earth, says Harris, and asteroids the size and distance of 2004 AS1 are “a dime a dozen.”

“I think we all realized the odds were in favor of the larger, more distant object, rather than a real impactor on its way in,” says Harris.

Chapman first discussed these events in a paper presented on February 22 at the Planetary Defense workshop for the American Institute of Aeronautics and Astronautics (AIAA).

“Just last month, perhaps the most surprising impact prediction ever came and went, this time out of the view of the round-the-clock news media,” said Chapman. “It illustrates how an impact prediction came very close to having major repercussions, even though — with hindsight — nothing was ever, in reality, threatening to impact.”

The Lincoln Near Earth Asteroid Research (LINEAR) observatories in New Mexico sends routine nightly observations to the Minor Planet Center (MPC) in Cambridge, Massachusetts. On January 13, when the MPC received the LINEAR data, they performed the usual computations, and five objects were automatically highlighted as being of potential interest. One of these objects was the asteroid that was initially named AL00667.

Information about the five objects was posted on the publicly accessible NEO Confirmation Page (NEOCP). This data is posted so that amateur and professional asteroid astronomers can follow up on the LINEAR observations each night.

The MPC didn’t notice right away that one of their highlighted objects appeared to have an interesting trajectory. But Reiner Stoss, an amateur astronomer in Germany, saw that AL00667 was predicted to get 40 times brighter over the next day. He shared this information on Yahoo’s Minor Planet Mailing List (MPML). Another amateur observer, Richard Miles in England, noticed the same thing and even took images of the predicted area in the sky (although he found nothing).

Harris was monitoring the MPML mailing list at the time, and his quick calculations indicated that the asteroid could strike as soon as one day. He hurriedly contacted his colleagues, including Don Yeomans and NASA Ames Research Center’s David Morrison, who is chair of the International Astronomical Union’s Working Group on NEOs.

The word on the potential asteroid threat was out, and members of the MPML swapped anxious speculations while the scientists swapped a flurry of e-mails and additional calculations. Steven Chesley, a researcher at JPL, sent an e-mail several hours later saying that after looking at all the available data, he estimated the asteroid had a 25 percent chance of striking the Northern Hemisphere as soon as the following night, or as late as a few days later.

To determine whether the asteroid really posed a threat to Earth, more observations were needed. But Mother Nature wasn’t cooperating. Heavy cloud cover obscured much of the night skies in both Europe and North America.

Finally, thanks to clearer skies over Colorado, amateur astronomer Brian Warner was able to use a 20-inch aperture telescope to look for the asteroid. His search covered a broader area of sky than had been searched by Miles, and it covered the entire area that the asteroid should have been within to be on a collision course with Earth. The asteroid wasn’t there, meaning it wasn’t going to strike us after all.

Chapman says part of the problem that night was that the LINEAR data was not as accurate as usual. He thinks the inaccuracy of this data may have been due to the cloudy conditions. The light from the waning quarter moon also may have been a factor.

There is a protocol set in place to prepare for a large asteroid impact, but no such plans exist for smaller asteroids that can catch us off guard. Larger asteroids would be noticed long before they approached Earth, and we would have years if not decades to make plans. But smaller asteroids can seemingly come out of nowhere, giving us much less time to plan.

If a small asteroid was going to strike the Earth in just a few days, both Chapman and Harris say there would not be enough time to deflect or destroy the asteroid. Instead, scientists would try to determine exactly where the asteroid was to hit so that the area could be evacuated, if necessary. But Chapman admits that it is not easy to figure out exactly where a small asteroid will strike the Earth.

“In the case of the 30-meter body, the danger zone would be no larger than a few tens of miles across,” says Chapman. “It is hardly certain that we would be able to predict ground-zero that accurately.”

There are thought to be more than 300,000 nearby small asteroids (asteroids about 100 meters across). Such asteroids should statistically hit Earth once every few thousand years. The most recent such asteroid strike occurred in 1908, when an asteroid measuring about 60 meters in diameter hit Russia. The “Tunguska” bolide exploded in the atmosphere and flattened about 700 square miles of Siberian forest.

Large (1 kilometer or greater) asteroids are far more rare and infrequent. There are only about 1,100 nearby large asteroids, and they are predicted to strike the Earth every half million years or so. But when these asteroids strike, they can cause catastrophic changes in the global climate. Asteroids that cause mass extinctions are thought to be 10 kilometers or greater in diameter.

The Spaceguard Survey was established to track large asteroids and comets that might pose a direct threat to Earth. So far, the Spaceguard Survey has found about half of these NEOs, and they expect to find the majority of them by 2008. The Spaceguard Survey telescopes also occasionally find smaller asteroids, such as the one discovered the night of January 13.

Although there are no current plans to establish a program to track the numerous small NEOs, Chapman says there have been proposals to do so. Such surveys would be able to track asteroids in the 150 to 500 meter range, and would find even smaller asteroids as well.


The NAS Visualization and Data Analysis team recently released a new database of pre-computed visualizations from the Estimating the Circulation and Climate of the Ocean (ECCO) project’s 14-month global ocean simulation, enabling scientists all over the world to download and customize the visualized data to support their own research.

As soon as the Aitken supercomputer's new nodes went into production after its recent expansion, NAS users quickly put them to use for their science and engineering projects.


Watch the video: The UnxPlained: The Unexplained Prophecies of Nostradamus Season 1. History (September 2021).