- Feb 5, 2008
- Reaction score
I guess some one suggested it and it just stuck....
According to the orbital data given on Heavens Above, it is on a hyperbolic orbit. Which means it's a one-time visitor to our solar system, and will continue to recede ever more slowly, until, by chance, in billions of years time, it might encounter another star. In the icy cold of interstellar space it won't change much, and will probably outlast humanity.rynner2 said:Bright comet 'lighting sky' as it flies by Earth
By Rebecca Morelle, Science reporter, BBC World Service
Stargazers could enjoy a rare spectacle as a bright comet swings into the Northern Hemisphere.
The icy mass, called C/2011 L4 Pan-Starrs, should be visible with binoculars or a telescope from 8 March.
It is thought to be a non-periodic comet, which means this could be the first time it has ever passed through the inner Solar System, and it might not return.
'Black glass' could be first comet chunk found on Earth
http://www.newscientist.com/article/dn2 ... lxkhFB4JBw
00:47 10 October 2013 by Lisa Grossman
A charred black pebble found in the Egyptian desert may be a piece of a comet that shattered near Earth about 28 million years ago. If so, the stone would offer a first close-up glimpse of rock that formed at the very edges of the solar system.
The 30-gram stone was discovered by Egyptian geologist Aly Barakat in December 1996 in a part of the Sahara desert near the border with Libya. The 6000-square-kilometre region is famous for being strewn with fragments of pale green glass, thought to have formed millions of years ago during a meteorite strike. Ancient Egyptians used a piece of this Libyan desert glass to make a scarab for King Tutankhamen's burial jewellery.
Barakat thought the darker stone might be a kind of black diamond called carbonado, so he sent a sample to Marco Andreoli at the University of the Witwatersrand in South Africa.
Years of analysis revealed that the rock may be something even rarer: the first large-scale piece of a comet. Until now, scientists had found only grains of cometary material in Earth's atmosphere and in carbon-rich dust in Antarctic ice. NASA's Stardust spacecraft also returned a few dust grains from comet Wild 2 in 2006.
"We can study material from the outermost solar system for the first time," says Jan Kramers, a member of Andreoli's team at the University of Johannesburg in South Africa. "This is actually quite exciting."
Kramers and his colleagues subjected a 1-gram sample of the stone to a barrage of tests to determine its composition. They found that the rock has a high ratio of oxygen to carbon – an unearthly mix similar to that seen in the Wild 2 samples and Antarctic dust fragments. They also found that the black rock contains chunks of diamond, which could have formed when its carbon was compressed by the high pressure of an impact.
"People think of comets as a dirty snowball made of ice that evaporates in the sunshine," says Kramers. "But the heat-resistant part of comets is carbon, and if you compress it, heat it up and subject it to shock, you get some kind of glassy carbon. This appears consistent."
The team then heated other fragments of the rock to 1800?C to release gases trapped inside. They detected the noble gases neon, krypton, xenon and argon. The argon isotope ratios confirmed that the rock is not originally from Earth. The other isotope ratios look nothing like those found in known meteorites, all of which came from asteroids, rocky objects that formed inside the orbit of Jupiter.
The team thinks that a comet hit our atmosphere and exploded over the desert, akin to what happened over the Tunguska region of Siberia in 1908Movie Camera. The explosion heated and compressed the sand to create the Libyan desert glass. The black stone is a piece from the comet's solid core, which absorbed noble gases from our atmosphere on its way down and turned its carbon into diamond on impact.
"You have Libyan desert glass, which is basically molten Earth surface material, and you have a piece which is basically a shocked fragment of cometary core in the same area, so you start putting 2 and 2 together," says Kramers.
"It is definitely a strange object, different from any meteorite we have sampled so far," says Ingo Leya at the University of Bern in Switzerland, who was not involved in the analysis. But while Leya agrees that the rock probably comes from space, he is not yet convinced it is a sample of a comet. "The problem is, we have little cometary material as a standard to compare with. Therefore it is difficult to firmly conclude or exclude that this meteorite comes from a comet."
The European Space Agency's Rosetta spacecraft is heading for a rendezvous with comet 67P/Churyumov-Gerasimenko (Chury) in 2014. It will deploy a small lander that will examine that comet's core up close, perhaps helping to settle the matter. In the meantime, Kramers hopes to find more samples of the Egyptian stone for study.
"It's a very inaccessible part of the Sahara, but there must be more material lying around," he says. "To go there and try to find more, you have to spend a lot of money, but not as much as to go and capture a comet in outer space."
Journal reference: Earth and Planetary Science Letters, DOI: 10.1016/j.epsl.2013.09.003
I checked HeavensAbove for an update. Ison is still only about 13.5 magnitude (way below naked eye visibility), but a decent telescope or large bins might find it.rynner2 said:Rosetta: Riding a ‘bucking bronco’ in space
The excitement is mounting. We're going to be talking about comets an awful lot in the coming months.
First of all, we have Comet Ison to enjoy. We hope.
This mountain of ice and dust has come hurtling in from the outer Solar System and is about to swing around the Sun.
At closest approach on 28 November, it will be no more than 1.2 million km (800,000 miles) from our star's boiling surface.
The big question is: will it survive the encounter? "Sungrazers" like Ison very often just fall apart. But if it can remain intact, this "dirty snowball" will swing back out past the orbits of the inner planets, potentially throwing off huge streams of gas and dust.
The comet could appear as a great arc across the sky, no binoculars required. Then again, it might not. Comets are notoriously unreliable.
Recent observations have suggested that Ison might fall short of being spectacular, but could still put on a decent show. We won't know for sure until December.
Secondly, from another thread - this contains quotes in bold from Exodus:On the 23rd, Ison will cross the orbit of Mercury, and that morning (UK time) it will also be its closest to Mercury in our sky, although sadly much closer to the horizon than the planet.
In fact, according to the Telegraph graphic, it will be not be seen from the 21st Nov to December 5th, when it reappears on the other side of the sun, becoming an object in the evening sky. Magic!
And these are some of the ideas that will be in my mind in the next few weeks. Fascinating to think that we may be about to witness something similar to what may have been seen in the times of the Israelite Exodus from Egypt. 8)Well, Professional Astronomers can play this game too!
I refer to Victor Clube and Bill Napier, who proposed (in at least a couple of books) that many of the disasters and strange events of early recorded human history were due to meteorite bombardment when a major comet broke up in the solar system.
By day the LORD went ahead of them in a pillar of cloud to guide them on their way and by night in a pillar of fire to give them light, so that they could travel by day or night. 22 Neither the pillar of cloud by day nor the pillar of fire by night left its place in front of the people.
This is a description of the comet, with its long tail, seen by night and day.
The pillar of cloud also moved from in front and stood behind them, 20 coming between the armies of Egypt and Israel. Throughout the night the cloud brought darkness to the one side and light to the other side; so neither went near the other all night long.
This is a description of the comet after it has passed perihelion (its closest approach to the sun), when it appears in the opposite part of the sky - it 'moved from in front and stood behind them'.
Now I'm not saying that Clube and Napier are right, but they do put together a very well argued and presented case.
And this is my point - stuff that happened thousands of years ago, of which we have only fragmentary remaining descriptions (many of which may have been re-interpreted in the following centuries) can have multiple 'explanations' in the light of modern science. Someday, maybe, we'll unearth sufficient evidence to work out what really happened.
In the meantime, we can only keep an open mind as we analyse any new ideas put forward.
http://www.forteantimes.com/forum/viewt ... 916#775916
Ison has brightened to mag. 5.2, but that's still only as bright as dim naked eye stars. So as it enters the dawn twilight it will become harder to see without bins, unless there is some spectacular outburst.Peripart said:I'm really hoping to get a good view of this comet at some point. I hit the road quite early most days to go to work, so if skies are clear, I may be lucky.
Oh Bugger! I was promised TWO naked eye comets this year!special_farces said: