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Space (or outer space) describes the vast empty regions between and around planets and stars. The study of these, and other, astronomical objects is called astronomy, one of the oldest sciences. It is often said that space exploration began with the launch of Sputnik 1, the first man-made object to orbit the Earth. Then, in an almost unbelievable feat of human achievement, in 1969 Neil Armstrong and Buzz Aldrin travelled to the Moon and set foot on the surface during the Apollo 11 mission. Recently, it has become clear that the possibility of space colonization may no longer be exclusively reserved for science-fiction stories, and many controversial issues surrounding space have come to light, including commercial spaceflight, space laws and space weapons.


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Titan, as photographed by the Cassini spacecraft in 2009

Titan is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found. Discovered on 25 March 1655 by the Dutch astronomer Christiaan Huygens, Titan is the sixth ellipsoidal moon from Saturn. Frequently described as a planet-like moon, it is the second-largest natural satellite in the Solar System, after Jupiter's moon Ganymede, and it is larger by volume than the smallest planet, Mercury. Titan itself is primarily composed of water ice and rocky material. Its dense, opaque atmosphere meant that little was known of the surface features or conditions until the Cassini–Huygens mission in 2004. Although mountains and several possible cryovolcanoes have been discovered, its surface is relatively smooth and few impact craters have been found. Owing to the existence of stable bodies of surface liquids and its thick nitrogen-based atmosphere, Titan has been cited as a possible host for microbial extraterrestrial life or, at least, as a prebiotic environment rich in complex organic chemistry.

Selected picture

Orion Nebula
Credit: Hubble Space Telescope

A composite photo of the Orion Nebula, the closest region of star formation to Earth. It is composed of 520 separate images and NASA calls it "one of the most detailed astronomical images ever produced". The nebula is located below Orion's Belt and is visible to the naked eye at night. It is one of the most scrutinized and photographed objects in the night sky, and is among the most intensely-studied celestial features.

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