Visit to Natural History Museum

On 1 September 2023 the Geology Group visited the Natural History Museum to learn about meteorites from Natasha Almeida, Curator of the Meteorites Collection

Brief history

Meteorites have been seen and recorded since Ancient Egyptian time.         – Tutankhamun had “glass” adornments and daggers which were traced to meteoritic material. In the late 18th century, a lot of interest was shown in objects falling from the sky, and study of the materials  was intensified with the invention of microscopes having rotating stages in 186.

Origins

There is a constant supply of meteorites from space found in areas of 
habitation in the Northern Hemisphere, and in Antarctica, where alien objects show up on the snow. Large meteorites have caused impact craters but due to intense burning up from high velocity descent, there is sometimes no evidence of the material to be seen. Many meteorites are released from the Asteroid belt and a number have originated from the Moon and from Mars. The NHM have 350 meteorites from Mars in their collection.

Materials

Meteorites vary, many are iron or stony-iron, known as chondrites, which
contain small particles of minerals known as chondrules.  Other meteorites are formed of breccias, some have silicate inclusions or calcium-rich inclusions.
The Moon material is anorthosite, pale grey, but originally white on acquisition. The 1 1/2k rock sample from Mars is contained in a partial vacuum. One source for collecting meteorites is from roof tops in areas of habitation, and in uninhabited desert areas. The “dust” collected is known as micrometeorites, which can be observed through microscopes.As a result of intense heat during travel, some meteorites show alterations on the surface, which can be shiny with criss-cross patterns at 60 degree angles, known as Widmanstatten pattern. A meteorite collected from the Libyan desert appears as a pale green piece of smooth glass, following fusion of the sand on meteorite impact

Collecting and Funding

Meteorites provide evidence for research into space and the origins of the Solar System. There is no real funding mechanism for acquisition of meteorites, the NHM relies on donations. The exhibits gifted in the past were often of colonial origin. There is some funding from NASA

▷ Images of meteorites

Recommended reading

Meteorites : the story of our solar system by Caroline Smith, Sara Russell, Natasha Almeida (Natural History Museum, 2019)

With thanks to Natasha for her knowledge and expertise and for such an enlightened
lecture

Penelope Badham

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