Impact threat from asteroid Apophis cannot be ruled out

June 26, 2017 by Tomasz Nowakowski, Astrowatch.net, Astrowatch.net

The famous near-Earth asteroid Apophis caused quite a stir in 2004 when it was announced that it could hit our planet. Although the possibility of an impact during its close approach in 2029 was excluded, the asteroid's collision with Earth in the more distant future cannot be completely ruled out.

"We can rule out a collision at the next closest approach with the Earth, but then the orbit will change in a way that is not fully predictable just now, so we cannot predict the behavior on a longer timescale," Alberto Cellino of the Observatory of Turin in Italy told Astrowatch.net.

While currently there are no near-Earth objects (NEO) on collision course with the Earth, this situation may dramatically change someday. Given that that NEO orbits are chaotic, what is not dangerous today can become a candidate impactor in the future.

"There are no known asteroids on a certain . Because of imperfectly known orbits, there are some that have a low probability of impact in the distant future, but at present none of the known asteroids has a probability of impact that exceeds the random chance of an undiscovered asteroid of the same size hitting the Earth sometime between now and the possible impact date of the imperfectly known object," Alan Harris, a former Jet Propulsion Laboratory (JPL) researcher told Astrowatch.net.

He added that this ratio forms the basis of the so-called "Palermo Scale" assigned to any object with a non-zero chance of impact. It is a logarithmic scale used by astronomers to rate the potential hazard of impact of a NEO.

A rating of zero means the hazard is equivalent to the background hazard—the average risk posed by objects of the same size or larger over the years until the date of the potential impact. A negative Palermo Scale value corresponds to a threat that is less than the general background risk of an impact.

"Apophis has a Palermo Scale rating of about minus three, so while we cannot rule out an impact in the future, it is about 1,000 times less likely than a random impact in the same interval of time. Due to a close but non-impacting pass by the Earth, there are numerous possible impact trajectories beyond that, but all are of very low probability," Harris said.

Discovered in June 2004 by Roy A. Tucker, David J. Tholen, and Fabrizio Bernardi at the Kitt Peak National Observatory in Arizona, asteroid Apophis is about 370 meters in diameter. Based on recent observations, the probability of an during its flybys of Earth on April 13, 2029 and on April 13, 2036 was eliminated by astronomers. The asteroid is constantly monitored in order to improve our knowledge of its orbit.

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markleaver1
5 / 5 (1) Jun 27, 2017
something to think about...

Before the Torino Color Scale was adopted by the IAU(1999), this meteor was being talked about.
Before the "Palermo Number Scale" was invented (2001), this meteor was being talked about.
Before Apophis was discovered and/or named in June 2004 by Roy A. Tucker, David J. Tholen, and Fabrizio Bernardi, this meteor was being talked about.

Billy Eduard Albert Meier was the person doing the talking about the Red Meteor aka Apophis since 1981.

for more info
theyfly.com
search Apophis or red meteor

and
Apophis (red meteor) from index of topics
futureofmankind.co.uk/Billy_Meier/Index#A
Da Schneib
1 / 5 (1) Jun 27, 2017
Meh. We've had a look and there's nothing that's a problem for a thousand years. We'll want to keep an eye out but this isn't anything like an imminent hazard.
Gigel
not rated yet Jun 27, 2017
Maybe it would be a good idea to mine this thing, just in case. It would be good to be on it (with a propulsion unit fueled by the Sun) just in case the rock thinks about coming our way.
antialias_physorg
5 / 5 (2) Jun 27, 2017
We've had a look and there's nothing that's a problem for a thousand years.

...of the ones we know of. Remember that the Palermo scale 0 rating just means 'same as background hazard' - where 'background hazard' means 'threat from undetected object'. There's plenty of objects in the 100m diameter range out there still to be found.
Gigel
5 / 5 (1) Jun 27, 2017
Those of sizes of tens of meters are potentially dangerous too. If they resist an atmospheric entry and drop on the sea floor they can cause tsunamis (probably by inducing movements of the sea floor or by activating tectonic faults) with devastating effects on the coastline. Also, they can cause climatic disaster by inducing global cooling. An average cooling of 5 deg. centigrade can be catastrophic for agriculture and it may last for years.
antialias_physorg
3 / 5 (2) Jun 27, 2017
Also, they can cause climatic disaster by inducing global cooling.

Even something the size of Apophis (which is rated at 300+ meters diameter) isn't going to cause global climate changes. It'd devastate a couple thousand square kilometers (or cause a tsunami if it hits the oceans) - but not cause any long lasting/global damage.

The energy would be about 15 times the largest bomb ever tested. That's pretty big, but still very localized.
markleaver1
5 / 5 (1) Jun 27, 2017
perhaps it is time to close up shop then for the next 1000 years.
it appears everyone but NASA's calculator is taking this seriously...
perhaps the calculator is the problem.
google... apophis russia china

here is a comic book that shows scientist inability to agree on how to deal with it, once they agree something needs to be done (nasa is not even there yet)
theyfly.com/The-Adventures-of-Billy-Meier.html
Gigel
not rated yet Jun 27, 2017
Also, they can cause climatic disaster by inducing global cooling.

Even something the size of Apophis (which is rated at 300+ meters diameter) isn't going to cause global climate changes. It'd devastate a couple thousand square kilometers (or cause a tsunami if it hits the oceans) - but not cause any long lasting/global damage.

The energy would be about 15 times the largest bomb ever tested. That's pretty big, but still very localized.

Not if it induces cooling by a different mechanism than dust raising into the atmosphere. What if it would send large amounts of water vapor into the stratosphere, which would then form long-lasting high clouds?
antialias_physorg
not rated yet Jun 27, 2017
As noted: it's not big enough for that.
Unless you get some very unlucky combination of it hitting a volcano and starting a super-eruption or somesuch. But that is exceedingly unlikely. Especially given the calculated potential impact places:
https://en.wikipe...Risk.jpg

Water vapor itself doesn't have a long remain time in the atmosphere (a few days. Thankfully. Otherwise we would have to worry about that in addition to CO2, as water vapor is a potent greenhouse gas). Water vapor would only remain in the atmosphere if Earth's atmosphere was heated significantly by the impact (which it isn't).
ulao
not rated yet Jun 27, 2017
With regard to the risk od tsunamis see:
https://www.space...tem.html
Gigel
not rated yet Jun 27, 2017
With regard to the risk od tsunamis see:
https://www.space...tem.html

They briefly mention seismic causes of tsunamis, but avoid discussing the possibility of an asteroid-caused earthquake, followed by a tsunami. An asteroid hitting the sea floor might induce a premature quake on a partially stressed fault line with some nasty consequences, including a tsunami.

Water vapor itself doesn't have a long remain time in the atmosphere (a few days.

As per the article posted by @ulao above, there is a possibility that water high in the stratosphere could remain there for months or years with climatic consequences. There was once an article on phys.org on ice clouds being able to remain in the stratosphere for long periods of time, but I can't find it.
Gigel
not rated yet Jun 27, 2017
Some articles mentioning the possibility of long-term catchment into the stratosphere:

https://phys.org/...ate.html

"Since the stratosphere is stable, if gas in volcanic plumes gets into the stratosphere, it stays there for a long time - a couple years"

https://phys.org/...ere.html

"Studies have shown even small changes in stratospheric humidity may have significant climate impacts"

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