Posted on 09/10/2010 5:37:03 AM PDT by Palter
A CELESTIAL event in the 5th century BC could be the earliest documented sighting of Halley's comet - and it marked a turning point in the history of astronomy.
According to ancient authors, from Aristotle onwards, a meteorite the size of a "wagonload" crashed into northern Greece sometime between 466 and 468 BC. The impact shocked the local population and the rock became a tourist attraction for 500 years.
The accounts describe a comet in the sky when the meteorite fell. This has received little attention, but the timing corresponds to an expected pass of Halley's comet, which is visible from Earth every 75 years or so.
Philosopher Daniel Graham and astronomer Eric Hintz of Brigham Young University in Provo, Utah, modelled the path that Halley's comet would have taken, and compared this with ancient descriptions of the comet (Journal of Cosmology, vol 9, p 3030). For example, the comet was said to be visible for 75 days, accompanied by winds and shooting stars, and in the western sky when the meteorite fell.
The researchers show that Halley's comet would have been visible for a maximum of 82 days between 4 June and 25 August 466 BC. From 18 July onwards, a time of year characterised in this region by strong winds, it was in the western sky. At around this time, the Earth was moving under the comet's tail, so its debris field would have made shooting stars.
None of this proves the comet's identity, but Graham says such major comet sightings are rare, so Halley must be a "strong contender". Previously, the earliest known sighting of Halley was made by Chinese astronomers in 240 BC.
(Excerpt) Read more at newscientist.com ...
True. But when you are famous, you have a lot of followers.
7 Most Massive Single Meteorites on Earth
Ahnighito or Tent meteorite c.1894: Photographer unknown via Meteorite Recon
Like fugitives on the run from distant solar systems, meteors hurtle through the earths atmosphere, lighting up the eyes of observers on the ground. Often these fireballs of metal and rock burn up in a blaze of glory, and many do not survive their impact with the Earths surface. Those that do though start a more settled life here on Earth as meteorites. Some might even claim to be the new sheriffs in town theyre that big and resistant to weathering.
Back in the day: Willamette meteorite pre-1923
Photographer unknown via NASA
Heres our magnificent 7 of the most massive known single meteorites on earth iron monsters that have remained in one piece for thousands of years.
Photo: Dante Alighieri
At 7.8 metre sq and 15.5 tonnes, Willamette is the largest meteorite found in the US, a peculiarly pitted lump composed of 91% iron and 7.62% nickel, with no impact crater preserved at its original site in Oregon.
Aspiring supermen: Two boys sitting in the Willamette Meteorite 1911
Photo: American Museum of Natural History published in the New York Times
Though revered by Native Americans who still contend it should be returned Willamettes modern discovery was made by settler Ellis Hughes in 1902. Recognising its significance, Hughes spent three months of hard labour moving the meteorite ¾ of a mile from land owned by the Oregon Iron and Steel Company to try to claim it as his own. He was caught however, and the meteorite was subsequently bought for $26,000, later to be displayed in the American Museum of Natural History.
Photographer unknown via Jensen Meteorites
Officially discovered in 1930 though at the time believed to be a stone sacred to indigenous people Mbosi is Tanzanias meteorite giant, a large piece of space metal estimated at 16 tonnes. As with many meteorites, there is no sign of the crater it must have created on striking the Earths surface, which may indicate that it rolled like a boulder after landing or simply affirm that it has been here for thousands of years.
On a pedestal: Mbosi meteorite 1967
Photographer unknown via Arquivos Do Insolito
Back in 1930, Mbosi was only half visible, so deeply was it buried in the soil; today the soil around it has been excavated and a plinth constructed beneath it, though its original position is said to be preserved.
Photo: FunkMonk
Discovered in 1963 by Vagn F. Buchwald, Agpalilik, aka the Man, is the fourth major piece of Greenlands Cape York meteorite and the smaller of the Capes two celestial visitors that make our top seven. Still, at a less than modest 20 tonnes, it's not to be scoffed at, and can be seen at the Geological Museum in Copenhagen.
Shifting a lump: Agpalilik meteorite being moved
Photographer unknown via Gabriel
The Cape York meteorite from which the Agpalilik is derived smashed into the Earth almost 10,000 years ago and is one of the largest iron meteorites on the planet. For centuries, Inuit living near the earlier located pieces used them as a source of metal for tools and weapons, before tales of their existence pricked the ears of scientists back in 1818. Between 1818 and 1883, five expeditions set out to track down the rogue iron source, all of which failed.
Photographer unknown via Meteorite Art
The great Bacubirito meteorite is undoubtedly Mexicos finest and one of the largest single space objects to have been sent on a collision course with the Earth and survived. Estimated to weigh 22 tonnes, this crooked, four-metre-long slab of iron is on display at the Centro de Ciencias de Sinaloa in Culiacan, where it draws visitors keen to measure up against it.
Dig this: Bacubirito meteorite found in 1863
Photographer unknown via Meteorite Art
The monster of a meteorite that is Bacubirito was discovered by American geologist Gilbert Ellis Bailey in 1892 who had been sent by Chicago journal the Interocean to Central and South America and excavated with the help of local people. Like all meteorites, it was named after the place where it was found. A mighty fallen shooting star.
Photo: VSmithUK
The largest chunk of the Cape York meteorite, Ahnighito, known to the Inuit as the Tent, is at 31 tonnes the heaviest meteorite ever moved by man. Rumours of the Greenland iron had reached scientific circles in 1818, but it was 1894 before the American Arctic explorer Robert E Peary finally located its source with the help of a nameless local guide.
Precarious operation: The Ahnighito being launched on board Peary's ship
Photographer unknown via Meteorite Recon
It took Peary three years to get the heavy meteorites onto ships not to mention the building of Greenlands only railroad plus invaluable Inuit help but the explorer did contrive to sell his prizes to the American Museum of Natural History for a cool $40,000. At the museum, where the meteorite remains to this day, a display stand needed to be built whose supports reach directly into the bedrock below to hold Ahnighitos massive 12.1 metre sq-bulk.
Photographer unknown via Planeta Pia
The largest fragment of the iron meteorite that splintered to form the Campo del Cielo group of meteorites and the 60 sq km crater field of the same name in Argentina, El Chaco is a colossal chuck of a space object. It is the second heaviest single-piece meteorite recovered on Earth though the total mass of the Campo del Cielo fragments would have it claim the title at a canter.
Halleluiah: Campo del Cielo's 37-tonne El Chaco put into scale
Photographer unknown via Jensen Meteorites
El Chaco was located in 1969 at a depth of 5 metres using a metal detector, though its surrounding craters estimated at 4,0005,000 years old were reported in 1576 and already well known to the aboriginal inhabitants of the area. Sensationally, in 1990 a local Argentinean police officer foiled a plot by meteorite hunter Robert Haag to steal El Chaco, which at the time had already been moved out of the country.
Photo: coda
The runaway winner at approaching twice the weight of its nearest rival, Namibias Hoba must have taken some stopping. Measuring over 6.5 metres sq, this 60-tonne slab of metal is believed to have been slowed by the Earth's atmosphere to the point where it fell to the surface at a speed that left it intact and barely buried. Its even been suggested that the meteorites unusually flat shape caused it to skip along much as a skipping stone bounces across water. Nice moves.
What have we here: One of the earliest known photos of the Hoba, around 1930
Photographer unknown via Giant Crystals
Thought to have landed less than 80,000 years ago, Hoba is composed of about 84% iron and 16% nickel, and remains the most massive known naturally-occurring hunk of iron at the Earth's surface. Due to its large mass, its not been moved from where it fell since being discovered in 1920 by a farmer ploughing his field who heard a loud scraping before his oxen came to a rather abrupt halt. Having suffered much vandalism, this beast is now visited by thousands of tourists a year.
One mighty meteorite: Early traveller visiting the exposed Hoba, around1955
Photographer unknown via Giant Crystals
Note: At a rumoured 28 tonnes, Armanty in Xinjiang, China should have made the roll-call, but unfortunately information and pictures pertaining to this meteorite were too scarce to come by.
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