January Gallery

Electron structure of helium atom

Electron density of a helium atom. This image represents the quantum cloud of electrons surrounding a helium atom. The colours represent the local electric charge density, essentially the probability that one might find one of the atom's four electrons at a given point. The colours run from blue (highest) to red (lowest). The chaotic appearance of the image is due to the presence of a nearby charged particle; when in equilibrium the atom would appear more symmetrical. This is a more appropriate image than the older ideas of fixed orbitals for electrons, sometimes referred to as the Bohr Model, and is due to the principles of modern quantum theory

© ARSCIMED/SCIENCE PHOTO LIBRARY

Col. SEM of head of zebra jumping spider, Salticus

Head of jumping spider. Coloured Scanning Electron Micrograph (SEM) of the head of a Zebra jumping spider, Salticus scenicus. Five of its eight eyes (green) are seen, one large pair at the front, and smaller eyes on the side. Beneath the eyes are mouthparts; walking legs are also seen. The Zebra jumping spider gets its name from white stripes which occur on its black abdomen. Jumping spiders have acute vision which assists in their jumping habit. They stalk their prey, then jump on them at the last moment. Salticus scenicus is the most common member of the family of jumping spiders, widespread throughout the Northern Hemisphere. Magnification: x85 at 6x7cm size. x225 at 8x6ins

© POWER AND SYRED/SCIENCE PHOTO LIBRARY

Artwork of various galaxies showing red shift

Red shift. Illustration of galaxies distributed in Space, with the furthest galaxies red due to "red shift". This effect was discovered by amateur as- tronomer William Huggins in 1868, who noticed that the light from some stars was further towards the red end of the spectrum. Huggins realised this was due to the Doppler effect: just as the noise of a moving vehicle changes as it passes, so light from a star changes in wavelength as the star moves towards or away from us. Stars moving away more quickly are more red. In 1929 another astronomer, Edwin Hubble, used red shift to show that the fastest-receding galaxies are also the most dist- ant, indicating that the Universe is expanding

© CHRIS BUTLER/SCIENCE PHOTO LIBRARY