Hoba Meteorite Namibia
The largest known of meteorite to crash to
HOBA METEORITE NAMIBIA. The largest known of meteorite to crash to earth... but why no impact crater?
The largest known of meteorite to crash to earth... but no impact crater?
Was discovered in 1920 on the Farm Hoba, near Grootfontein in northern Namibia by, the farm owner, Jacobus Hermanus Brits. The iron-nickel body was found partially buried in calcrete and is the largest known meteorite on the Earth. Its approximate measurements are 2.95 meters in length, 2.85, 0.75 to 1.2 meter in height. It has three definite corners - the fourth being rounded and weighs about 55 to 60 tons. The meteor is quite unusual in its shape being somewhat cuboid. It is estimated at being between 200 and 400 million years old and that it fell to earth only about 80,000 years ago. The size of the Meteorite as it entered the Earth's atmosphere would have been much larger and the burn-out would have presented a most impressive sight to any living creature that may have witnessed the event.Amazingly, there is no impact crater, and to this date there is no scientific explanation for this mystery. Could it be that the Hoba Meteorite entered the earth's atmosphere at a very low trajectory, impacted the surface far away and then bounced to its final resting place.
In 1954 the curator of the American Museum of Natural History in New York tried to purchase the Hoba Meteorite. It was only owing to transportation problems owing to its weight that the meteorite remained in Namibia. Immediately following this matter a group of concerned locals brought the 'near calamity' to light and the following year it was proclaimed a National Monument.
- Astronomical Origin: thought to be between 190 to 410 million years old
- Classification Ataxite: Iron alloy meteorite having a high nickel content. Comprising of approximately 82.4% Iron, 16.4% Nickel, with intergrowths of kamacite and taenite (see Widmanstatten Pattern below). 0,76% Cobalt, 0,04% Phosphorus, with small amounts of Carbon, Sulphur, Chromium and Copper. Traces of Zinc, Gallium, Germanium, and Iridium. There are also traces of rarer minerals that do not exist on the Earth: Schreibersite [(FeNi)P3], Troilite [FeS] and Draubreelite [FeCr2S4].
- Meteor Trajectory : Low - direction unknown
- Collision with Earth: Unknown, estimated - 80,000 years ago
- Location Of Landing: Farm Hoba +- 20kms west of Grootfontein
- Size of Meteorite: Length 2,95 m x width 2,85 m x depth of 0.75 to 1,2 m
- Weight: about 60 tons
having a composition of about a 90% percent iron and 10% nickel begins to cool. Calculations indicate that this cooling process, which takes place under zero gravity conditions, is extremely slow, being approximately 2°c per million years. As the temperature of the metal alloy meteorite slowly lowers to about 700°c the meteorite would still be in a liquid form, but within this approximate temperature range, bands of crystals of the two associated metals kamacite and taenite would begin to be formed in a process know as diffusion. (kamacite being formed in the low nickel phase while taenite is formed during the high nickel phase). At this temperature the composition of the kamacite would be about 4% nickel. Over a period of some further 200 million years the meteor's temperature would have cooled to about 600°c during which period the migration of nickel atoms within the cooling molten metal mass would have increased the nickel composition of the bands of kamacite to about 6% , Whereas the bands of taenite would have risen to have a nickel content of approximately 19%. At approximately 500°c the migration of the atoms ceases. The resultant crystalline structure of the metal mass is of a cross-hatched formation now named as the Widmänstatten Pattern . This condition is not found on any metal bodies originating on planet earth.
The Hoba Meteorite site is operated by the National Heritage Council. There are camping areas near to the Hoba Meteorite. There is no power and no hot water for showering, but the experience of sleeping next to the meteorite is worth it.
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