Images Dated 25th February 2003

MAP microwave background

Cosmic microwave background. Whole sky image of the cosmic microwave background made by the MAP (Microwave Anisotropy Probe) spacecraft. This map indicates that the age of the universe is around 13.7 billion years. The data also reveal that the universe is expanding at 71 kilometres per second per megaparsec (1 Mpc = 3262 light years). The colours reveal variations in the temperature of the universe in all directions. This correlates to the density of material at the time when the universe became transparent to radiation, about 380, 000 years after its creation. The denser regions (red, yellow) formed the seeds of galaxies and other structures. Data obtained in 2003

© NASA/SCIENCE PHOTO LIBRARY

Glaciation

Glaciation. Artwork showing ice sheets advancing and retreating during an Ice Age. The left side shows a glacial period when ice is advancing. The sheet flows down a steep slope and cracks, forming crevasses. The right side shows glaciers retreating during an interglacial period, and illustrates the distinctive landscape features they create, including: glacial lakes and rivers; erratics (isolated boulders, centre); eroded bedrock mounds (far right); an esker (winding ridge, runs down from glacier); terminal moraines (semicircular ridges of rubble left by retreating glacier); and a cirque (semicircular hollow, upper right). Melting ice has raised the sea level

© GARY HINCKS/SCIENCE PHOTO LIBRARY

CDK2 enzyme

CDK-2 enzyme. Molecular ribbon graphic of theCyclin-Dependent Kinase-2 (CDK2) enzyme whichpartly regulates the life cycle of human cells.CDK2 regulates the timing & coordination of eventswithin cells with a true nucleus (eukaryoticcells). The activation of CDK enzymes at specificcell cycle stages is believed to trigger the majorchanges of the cell cycle, notably when the cellbecomes committed to a new division cycle (the"Start" phase) & the beginning of cell division(mitosis). Their transient activation requiresbinding to cyclins, a family of proteins whoselevels vary throughout the cell cycle

© Lawrence Berkeley National Laboratory/Science Photo Library