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| 360-degree photographic panorama of the Milky Way showing our edge on view of the galaxy |
The Milky Way is made up of combined light of many of the 200 billion stars and nebulae in our Galaxy. The Galaxy consists of a central bulge surrounded by a thin disc and a spheroidal halo. The central bulge contains mainly older red and yellow stars. Matter in the disc is aggregated into spiral arms which contain young hot blue stars and nebulae. The oldest stars are situated in the sparsely populated halo. Our solar is in one of the spiral arms (the Orion arm), about halfway out from the centre, and from this position our view of the galactic centre is completely obscured by dust clouds.
Milky Way galaxy
Image of the Milky Way's galactic center in the night sky aboveParanal Observatory |
| Observation data |
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| Type | SBc (barred spiral galaxy) |
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| Diameter | 100,000 light years (30 kpc) |
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| Thickness | 1,000 light years |
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| Volume | 7.85 trillion cubic light years |
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| Number of stars | 200–400 billion (2–4×1011) |
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| Oldest known star | 13.2 billion years |
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| Mass | 7.0×1011 M☉ (1.4×1042 kg) |
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| Sun's distance to galactic center | 26,400±1,600 light years |
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| Sun's galactic rotation period | 250 million years (negative rotation) |
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| Spiral pattern rotation period | 50 million years |
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| Bar pattern rotation period | 15 to 18 million years |
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| Speed relative to CMBrest frame | 552 km/s |
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