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"I want to know why the universe exist, why there is something greater than nothing."
Steven Hawking
Scientist, Space Lover
Why isn't this small galaxy simple? The above image and contemporary observations of small nearby galaxy Leo A were supposed to show it has a simple structure. Now Leo A is known to be a dwarf irregular galaxy - one of the most common types of galaxies in the universe and a type that is likely a building block of more massive galaxy like our Milky Way Galaxy. In general, larger galaxies have recently been shown to continually eat, and be primarily composed of, many of the smaller satellite galaxies that have surrounded them. Leo A's surprising complexity indicates that that it, and possibly many small galaxies, have formation histories nearly as complex as large galaxies. Leo A spans about 10,000 light years and lies about 2.5 million light years away toward the constellation of Leo.
The beautiful Trifid Nebula, also known as Messier 20, is easy to find with a small telescope in the nebula rich constellation Sagittarius. About 5,000 light-years away, the colorful study in cosmic contrasts shares this well-composed, nearly 1 degree wide field with open star cluster Messier 21 (bottom right). Trisected by dust lanes the Trifid itself is about 40 light-years across and a mere 300,000 years old. That makes it one of the youngest star forming regions in our sky, with newborn and embryonic stars embedded in its natal dust and gas clouds. Estimates of the distance to open star cluster M21 are similar to M20's, but though they share this gorgeous telescopic skyscape there is no apparent connection between the two. In fact, M21's stars are much older, about 8 million years old.
The International Space Station is the largest object ever constructed by humans in space. The station perimeter extends over roughly the area of a football field, although only a small fraction of this is composed of modules habitable by humans. The station is so large that it could not be launched all at once -- it continues to be built piecemeal. To function, the ISS needs huge trusses, some over 15 meters long and with masses over 10,000 kilograms, to keep it rigid and to route electricity and liquid coolants. Pictured above, the immense space station was photographed from the now-retired space shuttle Atlantis after a week-long stay in 2010. Across the image top hangs part of a bright blue Earth, in stark contrast to the darkness of interstellar space across the bottom.
Expanse