Milky Way
spiral galaxy in the Local Group containing the Solar System; its appearance across the night sky in areas with little to no light pollution / From Wikipedia, the free encyclopedia
The Milky Way is our home galaxy. It contains around 400 billion stars,[11][12][13][14][15] including our Sun.[16]
Milky Way | |
---|---|
Observation data | |
Distance | 26.4 ± 1.0 kly (8.09 ± 0.31 kpc) (from Sun)[1][2][3] |
Characteristics | |
Type | Sb, Sbc, or SB(rs)bc[4][5] (barred spiral galaxy) |
Mass | 0.8–1.5×1012 M☉[6][7][8][9] M☉ |
Number of stars | 100–400 billion [(1–4)×1011][10] |
See also: Galaxy, List of galaxies |
The Milky Way has a diameter of 26.8 ± 1.1 kiloparsecs (87,400 ± 3,600 light-years) as measured using the D25isophote,[17][18][19] and is a barred spiral galaxy. The idea that the Milky Way is made of stars goes back to the Ancient Greek philosopher Democritus.[16]
The Milky Way has three main parts: a disk, where the Solar System is, a bulge at the core, and an outer halo all around it.[20] Although the word "disk" suggests it is flat, the Milky Way is actually not quite flat. It is slightly warped and twisted.[21]
This galaxy belongs to the Local Group of three large galaxies and over 50 smaller galaxies. The Milky Way is one of the largest galaxies in the group, second to the Andromeda Galaxy.[11] Its closest neighbour is the Canis Major Dwarf Galaxy, which is about 25,000 light years away from the Earth. The Andromeda Galaxy is moving towards the Milky Way Galaxy and will collide with it in about 3.75 billion years.[22] The Andromeda Galaxy moves with a speed of about 1,800 kilometres per minute.[16]
Origin: "Two of the Milky Way's earliest building blocks" are known; Shakti and Shiva seem "to be (left-overs or) remnants of two galaxies that (were joined or) merged ... with an early version of the Milky Way"; That seems to have happened "between 12 and 13 billion years ago";.[23]