Parsec
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The parsec is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres. The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 AU subtends an angle of one arcsecond. The nearest star, Proxima Centauri, is about 1.3 parsecs from the Sun: from that distance, the gap between the Earth and the Sun spans slightly less than 1/3600 of one degree of view. Most stars visible to the naked eye are within a few hundred parsecs of the Sun, with the most distant at a few thousand parsecs, and the Andromeda Galaxy at over 700,000 parsecs.
Milky Way
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The Milky Way is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.
The Galactic Center as seen from Earth's night sky (featuring the telescope's laser guide star). Listed below is Galactic Center's information.
The Milky Way as seen from a dark site with little light pollution
Photograph of the "Great Andromeda Nebula" from 1899, later identified as the Andromeda Galaxy
Bright X-ray flares from Sagittarius A* (inset) in the center of the Milky Way, as detected by the Chandra X-ray Observatory.