Chapter 23 – Our Galaxy A galaxy is an immense collection of stars and interstellar matter, and ours is called the Milky Way Galaxy . Until the twentieth century, it was believed that the sun and planets stood at its center, because interstellar dust obscured scientists’ views, allowing them only to see the nearest objects. Bright objects known as globular clusters (star clusters) help us determine our location in the galaxy. By using the period-luminosity relation, astronomers were able to determine our distance from these and other clusters. Infrared Light is particularly useful for seeing farther into the plane of the Milky way; the longer the wavelength, the farther the radiation can travel through interstellar dust without being scattered or absorbed. The disk of our Galaxy is about 50 kpc in diamater and about .6 kpc thick. The center of the Galaxy is surrounded by a distribution of stars, called the central bulge . It is estimated that our Milky Way contains about 200 billion stars.
- Spring '09
- galactic center