Hoba meteorite
| Hoba | |
|---|---|
 The Hoba meteorite in 2006. | |
| Type | Iron |
| Structural classification | Ataxite |
| Group | IVB |
| Composition | 84% Fe, 16% Ni |
| Country | Namibia |
| Region | Grootfontein, Otjozondjupa Region |
| Coordinates | 19°35′S 17°55′E / 19.583°S 17.917°E[1] |
| Observed fall | No |
| Fall date | 80,000 years ago |
| Found date | 1920 |
| TKW | 60 tonnes |
 Closeup of Hoba meteorite vandalism | |
 Related media on Wikimedia Commons | |
Hoba[1] (also known as Hoba West) (pron. "HOE-bah") is a meteorite that lies on the farm "Hoba West", not far from Grootfontein, in the Otjozondjupa Region of Namibia. It has been uncovered but, because of its large mass, has never been moved from where it fell. The main mass is estimated at over 60 tons, and it is the largest known meteorite (as a single piece) and the most massive naturally-occurring piece of iron known at the Earth's surface.
The fall
The Hoba meteorite is thought to have landed over 80,000 years ago. It is inferred that the Earth's atmosphere slowed the object down to the point that it fell to the surface at terminal velocity, thereby remaining intact and causing little excavation. The meteorite is unusual in that it is flat on both major surfaces, possibly causing it to have skipped across the top of the atmosphere in the way a flat stone skips on water.
Discovery
The Hoba meteorite left no preserved crater and its discovery was a chance event. The owner of the land is said to have encountered the object while ploughing one of his fields with an ox. During this task, the farmer heard a loud metallic scratching sound, before his plough came to a sudden stop. The meteorite was excavated soon after and identified and described by scientist Jacobus Hermanus Brits, whose report was published in 1920. This report can be viewed at the Grootfontein Museum in Namibia.
Description and composition
Hoba is a tabloid body of metal, measuring 2.7 by 2.7 metres (8 feet 9 inches) by 0.9 meters (3 feet). In 1920 its mass was estimated at 66 tons. Erosion, scientific sampling and vandalism have reduced its bulk over the years. The remaining mass is currently estimated at just over 60 tons. The meteorite is composed of about 84% iron and 16% nickel, with traces of cobalt. It is classified as an ataxite iron meteorite belonging to the nickel-rich chemical class IVB. A crust of iron hydroxides is locally present on the surface, owing to weathering.
Modern History
In the attempt to control vandalism, the Government of Namibia (then South West Africa), declared the Hoba meteorite to be a National Monument on March 15, 1955 with permission of Mrs. O. Scheel who was the owner of the farm at that time
In 1985, Rossing Uranium Ltd. made resources and funds available to the Namibian Government to provide additional protection against vandalism. In 1987 Mr. J. Engelbrecht, the owner of Hoba West farm, donated the meteorite and the site where it lies to the State for "educational" purposes. Later that year, the Government opened a tourist centre at the site. As a result of these developments, vandalism of the Hoba meteorite has ceased and it is now visited by thousands of tourists every year.
Notes and references
- Universe: The Definitive Visual Dictionary, Robert Dinwiddie, DK Adult Publishing, (2005), pg. 223.