Asteróide Apófis poderá colidir com a Terra em 2036


23 Mar 2009
Manta Rota - Algarve
Asteróide Apófis poderá colidir com a Terra em 2036:

Em 2004, cientistas da NASA anunciaram que o asteróide Apófis deveria colidir com a Terra em 2029. Mas segundo um relatório russo, a possibilidade de colisão com o nosso planeta deverá acontecer noutra data: a 13 de Abril de 2036.

Segundo os cientistas russos, o mesmo asteróide deverá passar muito próximo da Terra em 2029, e a força gravitacional exercida é tão grande que alterará a rota e, na sua próxima passagem, irá mesmo colidir com o planeta Terra. A probabilidade de colisão, segundo a NASA, é ainda de um em 250 mil.

Para a NASA, o cenário mais provável é de que o asteróide passe próximo da Terra já em 2012 ou 2013, e o objectivo é desenvolver meios para alterar a órbita do asteróide e reduzir essa probabilidade para zero.



19 Nov 2007
Há conteúdos de certas notícias que devem ser investigados e criticados antes de se lhes dar eco. Sem mais comentários, recomendo a leitura do artigo que transcrevo:

Repeat after me: Apophis is not a danger!

What is it with all the bad media reports of cosmic doomsdays? Betelgeuse last week, giant spaceships before that, and now Apophis. Sigh.

Here’s the scoop: I was tipped off about this by Jesse Emspak, who writes for the International Business Time (and who wrote a great article about the real opportunities represented by Apophis), and who told me about a Russian news site which, a few days ago, posted an article about the asteroid Apophis with the very menacing title, "Russian astronomers predict Apophis-Earth collision in 2036".

Sounds scary, right? One problem: it’s 100% utter crap.

First, the reality: Apophis is what’s called a near-Earth asteroid; it currently swings near our planet roughly every seven years. In April 2029 it will have an extremely near pass, getting so close it will actually be below our geosynchronous satellites! It will definitely miss us, but there’s a catch: if it passes us at just the right distance, Earth’s gravity will warp its orbit just enough that seven years later, Apophis will hit the Earth.

Let me be very, very clear: the odds of this happening are incredibly low, something like one in a 135,000. I fret about asteroid impacts, as you might imagine, but this one doesn’t worry me at all. The odds are so low I worry more about Snooki getting her own three-movie contract.

The reason the impact odds are so low, but not zero, is that we don’t precisely know Apophis’s orbit. There is a tiny region of space above the Earth called the keyhole, and Apophis has to pass right through it to have its orbit modified enough to hit us on the next path. We can’t know for sure if the rock will pass through the keyhole or not in 2029, but we can apply statistics and calculate that minuscule 0.0007% chance. And maybe it’s better to think of it as a 99.9993% chance it’ll miss.

Feel better?


OK, so what’s with that Russian news article? Besides the breathless — and totally wrong — headline, here’s the first line:

Russian astronomers have predicted that asteroid Apophis may strike Earth on April 13, 2036.

Bzzzzzt. While technically correct, this gives the strong impression that the odds of impact are high. That’s irresponsible journalism at best. Yet things quickly get worse:

"Apophis will approach Earth at a distance of 37,000-38,000 kilometers on April 13, 2029. Its likely collision with Earth may occur on April 13, 2036," Professor Leonid Sokolov of the St. Petersburg State University said.

Aiieeee! The collision is "likely"? Aiiieee!

Except for the small fact that, like I said, it’s not. In fact, even "unlikely" is way too strong a word for it. I’d bet my life savings against an impact.

But the article continues:

The scientist said, however, the chance of a collision in 2036 was extremely slim saying that the asteroid would likely disintegrate into smaller parts and smaller collisions with Earth could occur in the following years.

Well, for Pete(resburg)’s sake. Which is it? Likely, or extremely slim? Sigh.

That last bit is interesting, though. The asteroid would disintegrate? What?

Now, that’s not a totally crazy idea. Some asteroids are not actually solid; they’re more like flying piles of rubble held together by their own gravity. We’ve actually seen asteroids like this, so we know they exist. If they’re big enough, and pass close enough to Earth, our gravity could pull them apart. The thing is, Apophis is only about 250 meters across, which is on the small side for this happen. So why would the article say it might fly apart?

I decided I needed to go to the source.

Leonid’s meteor

I did a web search on the astronomer quoted in the article, Leonid Sokolov. I had never heard of him, but of course there are thousands of astronomers on the planet. A little digging on the ‘net turned him up, and as it happens he is in fact a Russian astronomer and a member of the International Astronomical Union. I found his email address, and sent him a carefully-worded email asking him if he felt the article represented his view fairly.

I got an email back later that night that was pretty clear:

This is "bad mass communication", journalist misunderstanding, not "bad astronomy" [...] The probability of Apophis collision in 2036 is VERY-VERY SMALL, but not zero, the probability of Apophis collision after 2036 is VERY-VERY-VERY SMALL, but not zero.

Aha! As I suspected, we have a case here of a journalist grossly misrepresenting what an astronomer said. I had at first wondered if maybe there was a mistranslation to English, but what Dr. Sokolov is saying is that the reporter really just screwed this up. Massively. And what Sokolov said in his email to me is essentially correct. The odds are very small but not zero, and the odds get even lower after 2036.

But what about that weird bit about Apophis disintegrating and pummeling us like a shotgun? Sokolov told me:

In my talk I have spoken about SCATTERING OF POSSIBLE TRAJECTORIES of Apophis after approach in 2029 and possible approach in 2036, NOT DISRUPTION of asteroid!

Ah, I see. The word "scattering" is where things went awry.

When we observe an asteroid, we cannot get its precise position in space. There’s always some uncertainty caused by various factors like measurement errors inherent in the images, atmospheric distortions blurring out the image of the asteroid, the effects of sunlight radiation pressure on the orbit, and lots of other things. So we get an orbit that’s not exact, and projecting that into the future makes it even worse. Sometimes that means we have no idea where the rock will be in a decade or two. However, in the case of Apophis, we do have a good enough orbit to nail down its position in April 2029 to a few kilometers, accurately enough to know it will miss, but not accurately enough to know if it’ll pass through the keyhole. The most likely path it will take is outside the keyhole, but the uncertainty in the orbit just barely overlaps the keyhole. That’s why we can say the odds are so low, but not exactly zero.

So after that pass in 2029, we don’t know its exact orbit. Think of it this way: imagine three rocks all lined up next to each other approaching the Earth. One is closest to us, one in the middle, and one farther away. The Earth’s gravity is slightly different on each one, so after the pass their orbits are all different. They will move apart over time, the Earth having — aha! — scattered them.

That’s what Sokolov meant. He calculated the possible orbits of Apophis after it passes us, and sees them diverging. So it was the potential paths of Apophis that get scattered, not the rock itself!

So the reporter messed that part up too.

This too shall pass

This kind of stuff really ticks me off, as you might have noticed. Scaring people is not something I take lightly, whether it’s frauds riling up parents about vaccines and autism, or making up stories about nearby supernovae and 2012. You may just blow it off and think that if people don’t educate themselves on science, well, caveat emptor. But I think that’s the wrong attitude; the fact of the matter is there’s just too much misinformation out there to expect people to educate themselves on everything. People have lives, they’re busy, they have other concerns. If they hear something like this and lack the critical thinking or educational background to parse the story correctly, then we are all to blame. It’s up to all of us to get out there and teach people how to separate reality from nonsense.

And I’m not a fool, I know that that’s impossible to do for everyone. But we can minimize it. And maybe, if we can get to enough folks, we’ll reach a critical mass — a herd immunity, if you will — where nonsense will find it can’t get a toehold. Enough people will know better that such antiscience, antireality thinking may become an endangered species.

And you know what? That’s one mass extinction I can live with.

... e se ainda quiserem ler outro artigo de opinião, mais terra-a-terra mas igualmente fundamentado:

Asteroid Apophis to Hit Earth in 2036? Calm Down, the Sky is NOT Falling

Posted by mattusmaximus on February 9, 2011

In recent days, one of the more popular news stories flying around the Internet has to do with a supposed “doomsday” asteroid called Apophis. And, according to some idiotic journalists who seem to want to push a sensationalistic “news” story, this asteroid is going to hit the Earth in 2036 with devastating consequences – in short, they say this is going to happen…

Well, I’m here to tell you that this is, to use the scientifically-accurate phrase, a complete load of crap. That’s because the original story, which came via a Russian “news” outlet, has been completely and thoroughly refuted by NASA and scientists worldwide…
Will Apophis Hit Earth in 2036? NASA Rejects Russian Report

In 2004, NASA scientists announced that there was a chance that Apophis, an asteroid larger than two football fields, could smash into Earth in 2029. A few additional observations and some number-crunching later, astronomers noted that the chance of the planet-killer hitting Earth in 2029 was nearly zilch.

Now, reports out of Russia say that scientists there estimate Apophis will collide with Earth on April 13, 2036. These reports conflict on the probability of such a doomsday event, but the question remains: How scared should we be? …

In answer to that question, I think we shouldn’t really be scared at all. When you crunch the latest numbers, the probability that Apophis will actually impact the Earth in 2036 is about 1-in-250,000. If you work that out to a percentage, it comes out to a 0.0004% chance the asteroid will hit Earth. That’s a pretty slim chance, and certainly nothing to get all upset about, in my opinion.

Let’s think of it this way: compare the probability that Apophis will hit Earth in 2036 with the chances of other unfortunate events (as reported by Popular Science magazine)…

Lifetime odds of dying from:

Any accident: 1 in 36

A motor vehicle accident: 1 in 81

A firearm: 1 in 202

Poisoning: 1 in 344

A falling object (terrestrial): 1 in 4,873

Drowning in a bathtub: 1 in 10,455

Being caught in or between objects: 1 in 29,860

Suffocation by a plastic bag: 1 in 130,498

So that means that you are about twice as likely to die by being suffocated in a plastic bag as compared to the chances that this “killer” asteroid Apophis will wipe out planet Earth. Stop and think about that for a moment… now, are you suddenly going to start demanding the recall of all plastic bags from society in order to protect humanity? No? Good.

Now, please don’t get me wrong – I think the issue of tracking & cataloging near-Earth objects (NEOs) is a very important one, precisely because we have solid evidence that NEOs such as asteroids & comet fragments can and do hit the Earth. In fact, this happens all the time, but the regular impacts are from smaller objects; the big, “planet-killer” type objects are fewer in number so the chances of one coming our way is comparatively small. But it could happen, and with the implications being what they are (i.e., the destruction of human civilization on Earth being among the worst-case scenarios) it would be prudent for us to invest at least some resources into these questions. And we have invested such resources into NASA’s NEO Program.

So, in conclusion, is the sky falling with regards to Apophis? No.

Should you go buying your own “asteroid apocalypse” bunker? No.

Should we then turn a blind eye to the potential threat of NEOs? No.

Should we invest a reasonable amount of money into researching this issue? Yes.

Interestingly enough, one thing we really can do when Apophis makes its closest approach to Earth in 2036 is use the opportunity to learn more about asteroids and the early solar system. In fact, some scientists already have plans to use Apophis as an amazing research opportunity!

If you’d like to know more about Apophis, and the related physics & astronomy behind it, I suggest taking a look at this entry over at Phil Plait’s Bad Astronomy blog.


9 Jan 2009
Inverness, Escocia
Naturalmente mais cedo ou mais tarde um asteroide ou cometa irá colidir com a terra. A última vez foi curiosamente em 2009, um pequeno meteorito que caíu na costa leste africana. Foi um corpo de 1-2 metros, colisões deste tipo são muito frequentes mas raramente detectadas.

Tunguska, há cerca de 100 anos, foi o último evento mais dramático (meteorito com cerca de 10-50 metros). E a história do Holoceno está recheada deste tipo de eventos. Eventos como o Aphophis são mais frequentes do que se julga. Um exemplo foi a possivel colisão de um asteroide com 100-500 metros, no Índico, em 3000 BC, o que provavelmente causou um tsunami monstruoso, e a inundação descrita na Bíblia e noutros textos religiosos Outro evento ocorreu na Alemanha


23 Jan 2007
Obrigada pelas respostas, uma pessoa lê tanta coisa que já não sabe filtrar o que é verdade... :(

A Net está cheio de lixo, eu nem tinha ouvido falar ainda desse cometa Elenin e ontem quando fiz uma pesquisa fartei-me de rir com as barbaridades que andam por aí.

Como em tudo vida, acho que não é muito difícil separar o trigo do joio.
Há e haverá sempre otários que engolem tudo o que lhes vendem. Desde o empresário que deu 50 mil euros a um gajo qualquer da Nigéria em troca de um milhão por causa de uma herança real que lhe prometeram por email, desde o cigano que vendeu um telemóvel a alguém que julgava que estava a comprar um iphone ou android topo de gama e quando abriu a caixa percebeu que era apenas uma carcaça de plástico made in china com uma espécie de sabão lá dentro, até aos que acreditam nos doomsdays, 2012, planetas e cometas malucos, blalabla.

Haverá sempre quem caia nisso, e haverá sempre quem se ria com tamanhos otários. É a lei de Darwin, que separa depois uns dos outros.

Para evitar ou reconhecer os embustes, basta usar um pouco a cabeça, que é para isso que ela serve. Normalmente basta observar pequenos e simples sinais, tudo o que for doom, é suspeito logo à partida :) Está ao alcance de qualquer um. Com a prática consegue-se distinguir os charlatães à distância, às vezes nem é preciso abrir um site, basta olhar para o nome do site ou para o titulo de determinado artigo, ou para a forma como está escrito, existe todo um estilo "literário" inconfundível na charlatanisse.


19 Nov 2007
Sobre a missão da NASA que "cartografou" os objectos do sistema solar próximos da terra (asteróides, cometas) - WISE (Wide Infrared Survey Explorer), ver

Uma missão polivalente, já que vai cartografar toda a "esfera celeste" em infra-vermelho; em primeiro lugar, já produziu um levantamento espectacular da cintura de asteróides, identificando algumas centenas de milhar de corpos nesta região e na órbita de Júpiter.

Talvez ainda não seja possível dizer que as surpresas, a partir daqui, serão improváveis, mas estaremos mais perto.