DARK AGES

A glassy carbon sphere that contains evidence of extraterrestrial impact.
The sphere measures about 0.3mm in width.
(Credit: SEM imaging by Jim Wittke)

Astronomers Unravel A Mystery Of The Dark Ages:
Undergraduates' Work Blames Comet For 6th-century 'Nuclear Winter'

Scientists at Cardiff University, UK, believe they have discovered the cause of crop failures and summer frosts some 1,500 years ago – a comet colliding with Earth.
Historical references from this period - known as the Dark Ages – are sparse, but what records there are, tell of crop failures and summer frosts.

Evidence from tree rings suggests the Earth underwent a series of very cold summers around 536-540 AD, indicating an effect rather like a nuclear winter.
The scientists in the School of Physics and Astronomy believe this was caused by a comet hitting the earth and exploding in the upper atmosphere.
The debris from this giant explosion was such that it enveloped the earth in soot and ash, blocking out the sunlight and causing the very cold weather.

Asteroid Impact Caused Ice Age Extinctions?

About 12,900 years ago, wooly mammoths, giant sloths, saber-toothed cats and other large animals inhabited North America - then suddenly disappeared. A team of scientists now propose that these extinctions were caused by a climate change triggered by a large impact event.