Tag: space

geology historical / biographies

Mysteries of time: A quest for the age of the Earth

David Alexander Gardiner (UK) The question of the age of the Earth and its former inhabitants is one of great interest to us all. Most are aware that the Earth is understood today to be approximately 4.6 billion years in age, but what is the story of the momentous quest – to unravel the mystery of time? Many early speculations as to the age of the universe abounded in ancient and medieval times. We are all familiar with the literalist understanding of the Old Testament, from which Archbishop Ussher famously calculated a 4004 BC date for the beginnings of the Earth. Yet, this was one of the shortest chronologies in existence: the Babylonians spoke of many hundreds of thousands; the Egyptians of many tens of thousands; and the Hindus many billions of years in their cosmological speculations of the past. However, all these early traditions were not scientific in basis. Rather, they were religious or philosophical and not based upon experimentation and observation. It would not be until after the Renaissance that people started employing scientific methodologies to unravel the mystery. Various early scholars speculated upon the Earth’s geological history, including Leonardo da Vinci, the universal genius. Leonardo noted that fossils had once been actual living creatures and that the ocean must have once covered the land. As regards the age of the world, however, few people dared to challenge the conventional wisdom based upon the Genesis narrative – one wonders what da Vinci’s own view might have been. However, … Read More

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space

Book review: Collecting spacerocks: a guide to Meteorites, Tektites and Impactites, by David Bryant

Jon Trevelyan (UK) This is a nice little guide for the non-specialist collector of all things that go bump from above (and the effects they have on the rocks they impact). As is clear from the title, the book covers three wide categories: meteorites, tektites and impactites. Broadly speaking, a meteorite is any piece of solid material that has arrived on Earth from space (and, of course, is not from the Earth in the first place, like space junk). Tektites are small, black, glassy objects found in great numbers in a roughly equatorial belt, which are thought to have been formed from molten debris by the impact of massive asteroids and/or comets. And impactites are rocks created or modified by the impact of a meteorite on the surface of the Earth. With that in mind, the book covers: what meteorites are; their origins and classification; tektites and impactites; what makes the big holes that you find in them; meteorites in human history; meteorites and meteorwrongs(!); obtaining, preparing and displaying meteorites; and where you can see them. That is, everything an amateur needs to begin to understand and enjoy the subject as a hobby. In fact, it is a useful and accessible guide to all those who appreciate that, unlike most of the (passive) subjects of astronomy (distant stars, black holes, spiral galaxies and so on), meteorites and their associates are quite literally tangible evidence of the moon, mars, and far distant objects and asteroids. For a self-published book, the style … Read More

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extra-terrestrial geology minerals space

Pallasites: The meteorite jewels in the crown

David Bryant (UK) Perhaps unsurprisingly (as a professional dealer in space rocks), I find all meteorites equally fascinating and, in their own way, aesthetically appealing. However, I have to admit, the meteorites known as the Pallasites, with their beautiful structure of olivine fragments suspended in a nickel-iron matrix, are probably the most visually exciting, particularly to the non-specialist. In addition to their undoubted beauty and rarity, Pallasites offer us an intriguing glimpse into the interior of a planet that make them among the most scientifically important of all meteorite types. The name Pallasite is derived from that of the German naturalist, Simon Peter Pallas. Pallas was one of those amazingly observant and gifted polymaths, who seem to have been a lot more abundant during the eighteenth century, as well as lending his name to a whole class of meteorite, an eagle, a warbler, two species of bat, a wild cat and dozens of other plants and animals. In 1772, Pallas obtained a 680kg lump of metal that had been found near Kransnojarsk in Siberia. When it was examined in St Petersburg, it was identified as a new type of stony meteorite. In keeping with tradition, it was named after the location where it was found, but, uniquely, the whole class of meteorites was named for Pallas. There is still some debate about the actual origin of Pallasites. Although some meteorologists contend that the stony-iron structure resulted from a collision between a nickel-iron asteroidal core and a chunk of mantle material … Read More

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