Photo célèbre de la Terre photographiée à partir de la lune le 13 décembre 1972 par l'expédition Apollo 17.
Saturne photographiée par la sonde Cassini le 18 décembre 2012
Source : nasa
Explanation : Above this boreal landscape, the arc of the Milky Way and shimmering aurorae flow through the night. Like an echo, below them lies Iceland's spectacular Godafoss, the Waterfall of the Gods. Shining just below the Milky Way, bright Jupiter is included in the panoramic nightscape recorded on March 9. Faint and diffuse, the Andromeda Galaxy (M31) appears immersed in the auroral glow. The digital stitch of four frames is a first place winner in the 2013 International Earth and Sky Photo Contest on Dark Skies Importance organized by The World at Night
Explanation: What happens when two galaxies collide? Although it may take over a billion years, such titanic clashes are quite common. Since galaxies are mostly empty space, no internal stars are likely to themselves collide. Rather the gravitation of each galaxy will distort or destroy the other galaxy, and the galaxies may eventually merge to form a single larger galaxy. Expansive gas and dust clouds collide and trigger waves of star formation that complete even during the interaction process. Pictured above is a computer simulation of two large spiral galaxies colliding, interspersed with real still images taken by the Hubble Space Telescope. Our own Milky Way Galaxy has absorbed several smaller galaxies during its existence and is even projected to merge with the larger neighboring Andromeda galaxy in a few billion years.