Images Dated 5th August 2011

Penrose stairs, artwork

Penrose stairs, computer artwork. This is an impossible figure created by the physicist Roger Penrose and used by M C Escher in his illustration Ascending and Descending. The staircase loops back to join itself whilst still appearing to have steps of the same size throughout, all going in one vertical direction. This is an example of an object that can be drawn but not created

© CLAUS LUNAU/SCIENCE PHOTO LIBRARY

Cell division, fluorescent micrograph

Cell division. Immunofluorescent light micrograph of a human epithelial cell (centre) during the interphase stage of mitosis. Mitosis is the cycle of replication and division by which new body cells are formed. Here, the chromosomes of the parent cell (blue) have begun to duplicate and pair up, and the microtubules (green) have formed. The microtubules will pull the chromosome pairs apart to opposite poles of the cell, in a process called cytokinesis. When the cell has split, two identical daughter cells are formed

© DR TORSTEN WITTMANN/SCIENCE PHOTO LIBRARY

Illustration of Alexander the Great on in battle on horseback with sword above head

adult, alexander the great, ancient civilizations, ancient greece, arms up, battle, confrontation, cut out, day, history, horse, incidental people, looking away, men, on the move, one animal, one person, outdoors, period costume, rearing, series, side view, studio shot, sword, watercolour painting, white background, horizontal, 25 May 21 01:05:52, 138705996

© TAG Creative