Size:
The stellar disk of the Milky Way galaxy is approximately 100,000 light-years (9.5×1017 km) in diameter, and is believed to be, on average, about 1,000 light years (9.5×1015 km) thick. It is estimated to contain at least 200 billion stars and possibly up to 400 billion stars, the exact figure depending on the number of very low-mass stars, which is highly uncertain. Extending beyond the stellar disk is a much thicker disk of gas. Recent observations indicate that the gaseous disk of the Milky Way has a thickness of around 12,000 light years (1.1×1017 km)—twice the previously accepted value. As a guide to the relative physical scale of the Milky Way, if it were reduced to 130 km in diameter, the Solar System would be a mere 2 mm in width. The Galactic Halo extends outward, but is limited in size by the orbits of the two Milky Way satellites, the Large and the Small Magellanic Clouds.
The stellar disk of the Milky Way galaxy is approximately 100,000 light-years (9.5×1017 km) in diameter, and is believed to be, on average, about 1,000 light years (9.5×1015 km) thick. It is estimated to contain at least 200 billion stars and possibly up to 400 billion stars, the exact figure depending on the number of very low-mass stars, which is highly uncertain. Extending beyond the stellar disk is a much thicker disk of gas. Recent observations indicate that the gaseous disk of the Milky Way has a thickness of around 12,000 light years (1.1×1017 km)—twice the previously accepted value. As a guide to the relative physical scale of the Milky Way, if it were reduced to 130 km in diameter, the Solar System would be a mere 2 mm in width. The Galactic Halo extends outward, but is limited in size by the orbits of the two Milky Way satellites, the Large and the Small Magellanic Clouds.
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