Images Dated 11th December 2003

Optical image of the North America nebula

North America nebula. True-colour optical image of the North America nebula (NGC 7000). This large nebula is about 3000 light years away, and lies in the constellation Cygnus. It is composed mainly of hydrogen gas, which glows due to ionisation by radiation from a young, hot and massive star at the nebula's heart. Hot massive stars live for a relatively short time, so such nebulae are usually of recent origin. The North America nebula is believed to be around 10 million years old. To the right of this nebula is part of the Pelican nebula (IC 5067-5070). This image was produced by digitally combining photographs taken by the Palomar Schmidt Telescope in blue and red light

© CELESTIAL IMAGE CO./SCIENCE PHOTO LIBRARY

Fossil sea scorpion or Eurypterid

Fossil sea scorpion or eurypterid in a mudstone deposit. Sea scorpions are an extinct group of arthropods which lived from the Ordovician to the Permian periods (500 to 225 million years ago). They lived in salty, brackish, & freshwater seas. They were related to horsehoe crabs, but not to the land scorpions which they happen to resemble. Eurypterids had a flattened pair of legs for swimming, and four to five pairs of walking legs. They captured their prey with sharp, pincer-like appendages (chelicerae). Photograph of a eurypterid found in a deposit from the Devonian period (395-345 million years ago), a time when eurypterids were the dominant arthropods

© KAJ R. SVENSSON/SCIENCE PHOTO LIBRARY