Asteróides, cometas e meteoritos - 2008

[Luis França]

Re: Asteróides, cometas, meteoros e meteoritos - 2008

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[Brunomc]

Re: Astronomia 2008

Aqui tá mais uma noticia.. tá quase na hora

Asteróide deve colidir com a Terra na noite desta segunda-feira

Objecto tem apenas um a cinco metros de diâmetro e não oferece riscos.
É a primeira vez que os cientistas conseguem prever uma colisão.


Quando todos acham que o mundo parece estar para acabar, vem a notícia: um pequeno asteróide, descoberto há poucas horas por um observatório do Arizona (EUA), deve colidir com a Terra às 23h46 desta segunda-feira (6). Mas, a despeito de quaisquer temores, não há perigo algum, segundo os astrônomos. Ele é dos pequeninos e deverá queimar por inteiro na atmosfera.


O objeto tem entre um e cinco metros de diâmetro e deve queimar completamente a alturas bem superiores às que os aviões costumam usar para transitar pelo mundo. Uma bola de fogo brilhante deve ser o único resultado observável.

"Queremos salientar que esse objeto não é uma ameaça", disse, em nota, Timothy Spahr, diretor do Centro de Planetas Menores da União Astronômica Internacional. "Estamos empolgados porque esta é a primeira vez que passamos a previsão de que um objeto entrará na atmosfera da Terra."

As chances estão entre 99,8% e 100% de que o objeto colidirá com nosso planeta, segundo cálculos de Andrea Milani, da Universidade de Pisa.

O meteoro deve ser visível do leste africano, e a expectativa é a de um grande show -- uma bola muito brilhante cruzando rapidamente o céu, de nordeste para sudoeste. O objeto deve adentrar a atmosfera sobre o norte do Sudão, numa diagonal suave, com relação à superfície.

O pessoal da IAU está ansioso, com a expectativa de que alguém consiga fotografar o fenômeno.

A despeito de não oferecer perigo, o fenômeno é um lembrete de que, vira e mexe, pedregulhos enormes podem colidir com a Terra, trazendo impactos para a vida. Os dinossauros que o digam.


Fonte : globo.com

http://g1.globo.com/Noticias/Cienci...+COM+A+TERRA+NA+NOITE+DESTA+SEGUNDAFEIRA.html

 

[Mário Barros]

Re: Astronomia 2008

Espetacular quem me derá vê-lo a estoirar na atmosfera

 

[Brunomc]

Re: Astronomia 2008

Espetacular quem me derá vê-lo a estoirar na atmosfera

Eu também gostava de ver..

 

[Vince]

Re: Asteróides, cometas, meteoros e meteoritos - 2008

Na 3ªfeira desfez-se na atmosfera sobre o Sudão, África, o Asteróide 2008 TC3 com 2 ou 3 metros de diâmetro. O evento nada teve de raro em relação a tantos outros idênticos, mas desta vez foi a primeira vez que um impacto deste género na atmosfera foi previsto com algumas horas de antecedência.

Impact of Asteroid 2008 TC3 Confirmed
Don Yeomans
NASA/JPL Near-Earth Object Program Office
October 7, 2008

Confirmation has been received that the asteroid impact fireball occurred at the predicted time and place. The energy recorded was estimated to be 0.9 to 1.0 kT of TNT and the time of detection was 02:45:45 on October 7 (Greenwich Standard Time). More details on this detection will be forthcoming. An additional confirmation was apparently reported by a KLM airliner (see: http://www.spaceweather.com/). As reported by Peter Brown (University of Western Ontario, Canada), a preliminary examination of infrasound stations nearest to the predicted impact point shows that at least one station recorded the event. These measurements are consistent with the predicted time and place of the atmospheric impact and indicate an estimated energy of 1.1 - 2.1 kT of TNT.

The follow-up astrometric observations from professional and sophisticated amateur astronomers alike were rather extraordinary, with 570 observations from 26 observatories being reported between the time of discovery by the Catalina Sky Survey to just before the object entered Earth's shadow (57 minutes prior to impact). All this happened in less than 19 hours!

http://neo.jpl.nasa.gov/news/news160.html

Asteroid Exploded in Earth's Atmosphere
By SPACE.com Staff

posted: 08 October 2008
01:26 pm ET

A small asteroid exploded over Africa this week following what astronomers said was the first firm prediction of an incoming space rock.

It did not strike Earth.

The asteroid was about the size of kitchen table, astronomers estimated, and they think the explosion (caused by the pressures of slamming into the atmosphere) left nothing but perhaps a few small bits to fall to the surface.

No photographs of the explosion have been reported, owing to the remote location of the object's path over Sudan. But the explosion was recorded by an infrasound array in Kenya. Peter Brown at the University of Western Ontario estimated, based on the infrasound data, that the asteroid exploded at 0243 UT with an energy of somewhere between 1.1 and 2.1 kilotons of TNT.

On Monday, NASA researchers and other scientists announced that the space rock, named 8TA9D69, would enter the air at 10:46 p.m. ET (0246 UT) on Oct. 7 over northern Sudan. Such events occur a few times every year, but never before had one been predicted. The object was expected to create a very bright fireball that, for anyone who might have seen it, would have been far more dramatic than the typical shooting star resulting when small debris streaks through Earth's atmosphere.

"A typical meteor comes from an object the size of a grain of sand," Gareth Williams of the Minor Planet Center explained just before the highly anticipated event. "This meteor will be a real humdinger in comparison!"

There has been one visual confirmation of the exploding fireball, according to Spaceweather.com. Jacob Kuiper, a general aviation meteorologist at the National Weather Service in The Netherlands, told pilots to keep an eye out.

"I have received confirmation that a KLM airliner, roughly 750 nautical miles southwest of the predicted atmospheric impact position, has observed a short flash just before the expected impact time 0246 UTC," Kuiper said. "Because of the distance it was not a very large phenomenon, but still a confirmation that some bright meteor has been seen in the predicted direction."

The rock was discovered by an ongoing survey at Mt. Lemmon run by the University of Arizona as part of the NASA-funded Catalina Sky Survey for near-Earth objects.

Weather Eye: Nasa spots asteroid before annihilation
Paul Simons

In the early hours of yesterday morning a fireball exploded with the equivalent of a thousand tonnes of TNT over northern Sudan. The light was so intense that it lit up the sky like a full moon and an airliner 1,400km (870 miles) away reported seeing the bright flash.

The explosion was caused by an asteroid the size of a boulder roughly three metres (10ft) across. It sounds catastrophic, but the rock was totally annihilated as it smashed into the atmosphere, and there was no chance of it hitting the ground. In fact, asteroids this size hit the Earth’s atmosphere every few months or so. But this particular event was special because the asteroid was spotted before it blew up, the first time this has been achieved. The asteroid was seen by astronomers on Sunday at an observatory in Arizona, as part of a Nasa project to scan for approaching space rocks.

There are 5,681 such near-Earth objects, but only 757 of them are considered large enough to cause any damage if they hit Earth. If a dangerously large object were spotted in time the hope is to give enough warning to evacuate any people living in the likely crash zone, although the logistics involved would be mind-boggling.

However, it would be difficult to escape a 300m space rock. These strike every 60,000 years or so, and could trigger a monster-sized tsunami if they hit the sea. And an asteroid measuring more than a kilometre in diameter strikes Earth roughly every few hundred thousand years. This would obliterate everything in and around the impact zone and send the world’s climate into such turmoil that civilisation as we know it would collapse.

Asteróide deve colidir com a Terra na noite desta segunda-feira

Objeto tem apenas um a cinco metros de diâmetro e não oferece riscos.
É a primeira vez que os cientistas conseguem prever uma colisão.

Quando todos acham que o mundo parece estar para acabar, vem a notícia: um pequeno asteróide, descoberto há poucas horas por um observatório do Arizona (EUA), deve colidir com a Terra às 23h46 desta segunda-feira (6). Mas, a despeito de quaisquer temores, não há perigo algum, segundo os astrônomos. Ele é dos pequeninos e deverá queimar por inteiro na atmosfera.

O objeto tem entre um e cinco metros de diâmetro e deve queimar completamente a alturas bem superiores às que os aviões costumam usar para transitar pelo mundo. Uma bola de fogo brilhante deve ser o único resultado observável.

"Queremos salientar que esse objeto não é uma ameaça", disse, em nota, Timothy Spahr, diretor do Centro de Planetas Menores da União Astronômica Internacional. "Estamos empolgados porque esta é a primeira vez que passamos a previsão de que um objeto entrará na atmosfera da Terra."

As chances estão entre 99,8% e 100% de que o objeto colidirá com nosso planeta, segundo cálculos de Andrea Milani, da Universidade de Pisa.

O meteoro deve ser visível do leste africano, e a expectativa é a de um grande show -- uma bola muito brilhante cruzando rapidamente o céu, de nordeste para sudoeste. O objeto deve adentrar a atmosfera sobre o norte do Sudão, numa diagonal suave, com relação à superfície.

O pessoal da IAU está ansioso, com a expectativa de que alguém consiga fotografar o fenômeno.

A despeito de não oferecer perigo, o fenômeno é um lembrete de que, vira e mexe, pedregulhos enormes podem colidir com a Terra, trazendo impactos para a vida. Os dinossauros que o digam.

http://g1.globo.com/Noticias/Cienci...+COM+A+TERRA+NA+NOITE+DESTA+SEGUNDAFEIRA.html

 

[Vince]

Trio of asteroids buzz Earth

Trio of asteroids buzz Earth

We've been missing asteroids that have barely been missing us. All of us, that is, except a small band of asteroid hunters who've lately spotted some surprisingly tiny space rocks that have come closer to Earth than any found before.

On 6 October, they spotted an asteroid a few metres in diameter called 2008 TC3 just hours before it plunged into the atmosphere over Sudan.

Three days later, they spotted a metre-size space rock designated 2008 TS26 a few hours after it missed the Earth by 7000 kilometres. And on Tuesday, they spotted a slightly larger object called 2008 US that just hours earlier passed some 25,000 km above the surface.

Those are three of the four recorded objects that have come closest to Earth, according to a tabulation by the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics. The fourth, 2004 FU162, missed the Earth by a mere 6500 kilometers in 2004.

This month's sudden rash of discoveries doesn't mean something up there has started taking pot shots at us. They come because asteroid hunters are improving their searches. "We're getting better at spotting asteroids, and we expect many more discoveries in the future," says Gareth Williams, associate director of the Minor Planet Center.

The three latest objects were all spotted first by the Mount Lemmon Survey, which searches for asteroids with a renovated 1.5-metre telescope in Arizona. Two asteroids were only a few metres in diameter, and the smallest was only about a meter, making spotting and tracking the objects in space an impressive achievement.

So what's to worry about? We didn't see 2008 US or 2008 TS26 until a few hours after they made their closest approaches to the Earth because both were heading out from the Sun - and were lost in its glare - when they crossed the planet's orbit. That's no big deal because if such small objects hit the atmosphere, they would have streaked harmlessly across the sky as fireballs, like 2008 TC3. But it does remind us that asteroid hunters have a blind spot, and can't see objects coming from inside the Earth's orbit.

That blind spot is one reason it's important to catalogue and track Earth-crossing asteroids large enough to crash to the surface. Our brief observations of 2008 US didn't give enough information to calculate its orbit precisely, and Williams says we're not likely to see it again.

The good news is that bigger, more dangerous asteroids are brighter and easier to follow in the sky, so most of their orbits are known too well for them to surprise us by coming from out of the Sun. Next year, Canada will launch a small satellite that developers hope can spot asteroids inside the Earth's orbit. US astronomers have proposed orbiting a satellite around Venus to hunt for such asteroids. But can we ever completely eliminate the danger of unknown objects?

http://www.newscientist.com/blogs/s...z-earth.html?DCMP=ILC-hmts&nsref=specrt10_pic

 

[Huelva-Espanha]

Este topico es muito interesante

 

[Vince]

Espectacular captura em vídeo de um meteoro no Canadá. Ainda não se sabe se caiu algum resto em Terra, há actualmente uma caça ao meteorito na região.

Meteor blazes across the sky in police video
A spectacular and almost blindingly bright meteor sparked a flurry of emergency calls to the police after it lit up the skies over western Canada.

Onlookers across the province of Alberta watched in awe, describing a kaleidoscope of colours as the rock rapidly descended.

'At first I thought it was fireworks,' farmer Marcel Gobeil said.

'I've never seen anything like it; it was green and blue and then turned to bright red. It was pretty big.'

Emergency services across the region began receiving calls from 5.30pm on Thursday, with some also reporting hearing a distant 'boom.'

And the police had no reason to doubt the claims. A video camera on one of their local patrol cars had captured the whole dramatic episode.

As the vehicle cruises down a street the footage shows a small bright light appearing in the sky before hurtling towards the Earth disappearing in an explosion of light just five seconds later.

Shawn Mitchler was pumping petrol into his car in Radisson, when he saw the 10-second light show.

'My heart just started racing because I didn't know what it was,' he told The Windsor Star.

'It seemed like fireworks or a missile coming down,' he said.

Astronomers will assess tapes and eyewitness reports to try and discover where the meteor fell, although Edmonton scientist Alister Ling said early analysis suggests central Alberta.

Chris Herd, a professor from the University of Alberta said the descriptions suggested the meteor could in fact be a substantial meteorite weighing a few tonnes and measuring a few metres across.

More meteorites, fragments of rocks or metals that survive the fall from space to Earth, have been found in Alberta than any other Canadian province.

'The question now that remains is whether anything made it to the ground,' Professor Herd said.

'This thing was so bright it indicates that it's a pretty good-sized piece of space rock.'

Though one video viewer had his own hypothesis: 'Perhaps it was the toolbox dropped by the female astronaut recently?' he said.

http://www.dailymail.co.uk/sciencet...ar-struck-Meteor-blazes-sky-police-video.html

 

[Brunomc]

grandes videos..o meteorito fez um efeito de luz espectacular

 

[Teles]

Para variár a desilusão este ano foi igual com a chuva de meteoros Leónidas,
associadas à passagem do cometa Tempel-Tuttle, com inicio a 14 de Novembro e com maior actividade nos dias 17/18 e 19 deste mês, a expectativa de uma grande chuva na madrugada de 18 de Novembro foi um fracasso mais uma vez.
Restanos esperar por as Quadrantids em Janeiro

 

[*Dave*]

Espectacular captura em vídeo de um meteoro no Canadá. Ainda não se sabe se caiu algum resto em Terra, há actualmente uma caça ao meteorito na região.

Espantoso mesmo .

 

[bluejay]

Para variár a desilusão este ano foi igual com a chuva de meteoros Leónidas,
associadas à passagem do cometa Tempel-Tuttle, com inicio a 14 de Novembro e com maior actividade nos dias 17/18 e 19 deste mês, a expectativa de uma grande chuva na madrugada de 18 de Novembro foi um fracasso mais uma vez.
Restanos esperar por as Quadrantids em Janeiro

Tens as fiéis Géminidas antes se o tempo permitir.

 

[Luis França]

Cosmic Rays Coming From Mysterious, Nearby Object

An international team of researchers has discovered a puzzling surplus of high-energy electrons bombarding Earth from space. The source of these cosmic rays is unknown, but it must be close to the solar system and it could be made of dark matter. Their results are being reported in the Nov. 20th issue of the journal Nature.

"This is a big discovery," says co-author John Wefel of Louisiana State University. "It's the first time we've seen a discrete source of accelerated cosmic rays standing out from the general galactic background."

Galactic cosmic rays are subatomic particles accelerated to almost light speed by distant supernova explosions and other violent events. They swarm through the Milky Way, forming a haze of high energy particles that enter the solar system from all directions. Cosmic rays consist mostly of protons and heavier atomic nuclei with a dash of electrons and photons spicing the mix.

To study the most powerful and interesting cosmic rays, Wefel and colleagues have spent the last eight years flying a series of balloons through the stratosphere over Antarctica. Each time the payload was a NASA-funded cosmic ray detector named ATIC, short for Advanced Thin Ionization Calorimeter. The team expected ATIC to tally the usual mix of particles, mainly protons and ions, but the calorimeter found something extra: an abundance of high-energy electrons.