Milky Way

The galaxy that the solar system belongs to.

History of science The Milky Way was observed by people in ancient times; they so named the galaxy because of the milky appearance in the sky of the faint and irregular band of light. It was studied in 1610 by Galileo, who identified many stars, and by Herschel, who mapped out its shape.
It was Hubble who showed the existence of other galaxies, in 1924.

In 1951, using radio astronomy, it was shown that our galaxy is a spiral one, 100 000 light-years in diameter with a thickness of only 1000 to 3000 light-years. It is only observable in profile. The Sun is located in one of the spiral arms.