Hoba Meteorite - Fragment of a Dwarf Planet - News - Gondwana Collection


Gondwana's Newsroom

Hoba Meteorite - Fragment of a Dwarf Planet

Avatar of inke inke - 06. novembre 2015 - Discover Namibia

The meteorite on the farm Hoba, 20 km west of Grootfontein. Photo: Sven-Eric Kanzler

“Beware of falling meteorites!” The warning on a sign on the way to the meteorite on the farm Hoba, some 20 km west of Grootfontein, is in jest of course. It has been almost 80,000 years since a meteorite fell from the sky and hit this spot. But there is a grain of truth in the banter. According to estimates the earth is hit by approximately 500 meteorites per year. Most of them are rather small, ranging in size from that of a glass marble to a basketball, and for the most part they go unnoticed. The Hoba meteorite, on the other hand, is a chunky fragment weighing tons. It is likely to have caused a violent tremor when it crashed into the earth. 

For almost 80,000 years the Hoba meteorite lay undetected until it was accidentally discovered in 1920 by farmer Jacobus Hermanus Brits: “ ... I spotted an unusual rock and went to rest on it. Only the upper part protruded from the ground. The rock was black and surrounded by limestone. I applied my knife to it and noticed that the spot where I scraped became glossy. So I chiselled a piece from it and took it to the South West Africa Company in Grootfontein. The director concluded that it was a meteorite.”(quoted from the German translation in a travel guide entitled “Namibia”, by Wendula Dahle and Wolfgang Leyerer, 2001, p. 382).

The fact that the scraped spot turned glossy immediately indicated to the laboratory staff what to expect from the analysis. The meteorite largely consists of iron - 82.4 percent of it, to be precise. It is further composed of 16.4 percent nickel and 0.76 percent cobalt. This makes it an iron meteorite. Only about 6 percent of all meteorites fall into this category, the majority being rock meteorites. Its composition in turn enables conclusions to be drawn about its origin and age. Experts believe that the Hoba meteorite is a fragment of an asteroid, a small celestial body which shattered when it collided with another orb. The Asteroid Belt between Earth and Jupiter contains thousands and thousands of small celestial bodies orbiting the sun as do the planets. The Hoba meteorite is estimated to be 190 million to 400 million years old, which makes it much younger than the earth (4.5 billion years).

The Hoba meteorite stands out from among the multitude of found meteorites not only because of its composition but also because of its size. It is 2.70 metres long, 2.70 metres wide and 0.90 metres thick and it weighs about 60 tons. With these dimensions it is certainly one of the largest meteorites so far discovered on earth. It is still unclear why the meteorite hit the ground without forming a crater. Single meteorites, by the way, are unusual. As they enter the earth’s atmosphere, larger celestial bodies usually shatter into many fragments. One example is the meteorite shower near Gibeon where fragments of an iron meteorite, which most probably was more than double the size of Hoba, were scattered over an area of 20,000 square kilometres. (Some of the fragments can be admired on the fountain in the Post Street Mall pedestrian area in Windhoek.

But back to the initial question: does one have to look out for celestial bodies falling from the sky? Only a few of the approximately 500 meteorites that hit the earth every year are noticed. However, some 100 cases are known in which chunky pieces from space have caused material damage or killed animals.

Some known examples include the 12 kg Peekskill meteorite that damaged a parked car in the US state of New York on 9 October 1992. The rock meteorite at Valera in Venezuela hit a cow and almost split the animal in half on 15 October 1972. The 5.56 kg meteorite at Sylacauga in the US state of Alabama smashed through the roof of a house and hit a woman lying on the couch on 30 November 1954. Luckily the impact was softened by the roof and the woman escaped with a just a fright and a few serious bruises. Then there is that meteorite of unknown size that is thought to have collided with Earth some 65 million years ago, causing a tremendous explosion and volcanic activity and ultimately the extinction of the dinosaurs. Perhaps we should not laugh too loudly about the joke on the danger sign near Hoba ...

Comments are disabled for this post.


Stay up-to-date with our monthly 'Gondwana Tracks' Newsletter Sign up Today