Evolution Gallery

Orion nebula

Orion nebula. Coloured composite infrared and visible light image of the Orion nebula M42. This emission nebula, a cloud of gas and dust in which starbirth takes place, is found in the constellation Orion, some 1500 light years from Earth. Glowing clouds of ionised hydrogen and sulphur gases are green, and cool clouds of polycyclic aromatic hydrocarbons are orange and red. The gases are ionised by radiation from the four young Trapezium stars at the core (centre left). The small orange dots are embryonic stars, growing as they accumulate dust and gas. M42's neighbour, the M43 nebula, can also be seen (pale blue, top left). Infrared data from the Spitzer Space Telescope, visible light data from the Hubble Space Telescope

© NASA/JPL-CALTECH/STSCI/SCIENCE PHOTO LIBRARY

Diagram showing the spectral class and luminosity of stars

Diagram showing the spectral class and luminosity of stars. The diagram was named The Hertzsprung-Russell Diagram, or the H-R diagram for short. At the beginning of the 20th century two astronomers found that if stars were plotted on a diagram with their luminosity (brightness) on one axis, and their spectral class on the other, that stars formed three distinct groups. The largest group, the Main Sequence Stars, is where 90% of the stars are found. These stars are fusing hydrogen into helium in their cores. This group propagates diagonally from the upper left corner, down to the right corner. The group below the main sequence is the White Dwarfs, which is a group of small, earth-sized stellar remnants. The third group, which is found above the main sequence is that of the giants.
Stars appear on a specific place on the main sequence depending on their mass and age. The mass determines when it will leave the main sequence.The H-R diagram is a significant tool for astronomers, when it comes to understanding stellar evolution

© Fahad Sulehria/Stocktrek Images

1863 Huxley from Ape to Man evolution

Ordered series of primate skeletons. The Frontis engraving by Waterhouse Hawkins from the first edition of Huxley's 1863 "Evidences as to Man's Place in Nature". In this book Huxley presented his evidence that man was descended from the apes. It was published in reaction to Darwin's "On the Origin of Species" 1859. Though this image is often interpreted as indicating a line of descent, it is more intended to show ordered variation in limb bones and posture as well as the clear skeletal similarities in the group. The image has been quoted as an inspiration for Rudolph Zalinger's famous Time-Life 1965 image "The Road to Homo Sapiens" (page 40-45, Nature Library Early Man). That iconic image has become known as "The March of Progress". The artist for this work, Benjamin Waterhouse Hawkins, was famous for his pioneering dinosaur reconstructions but lectured against Darwinian evolution

© This image is Paul D. Stewart 2009. Do not reproduce without permission of the photographer at Stewartpauld@aol.com