The Nucleus of the Galaxy

(Section Not Complete)

The band of light that we call the Milky Way is actually the plane of the disk of our galaxy. The approximately 200,000,000,000 stars that make up our galaxy are mostly grouped into a flattened disk which has a bulge at its centre. The Sun is in this disk about two thirds of the way from its centre to its edge. When we look at the night sky we see the Milky Way when we look along the plane of this disk whereas when we look in other directions, out of the plane, we see far fewer stars.

The adjacent image shows the Milky Way in the direction of Sagittarius. The core of the galaxy lies near the center of this image, but we cannot see it in visible light because the intervening dust clouds block the light coming from the center (img Source).

However, visible light is not the only wavelength at which modern astronomers can make observations. The image below is taken in the infrared (IR) region of the electromagnetic spectrum using the Diffuse InfraRed Background Experiment (DIRBE) of the Cosmic Background Explorer (COBE).

Unlike visible light, which is strongly absorbed by the intervening gas and dust, the infrared light is transmitted well enough to give us a clear view of the central region. Thus, we see the side of the bulge surrounding the galactic core from our position in the disk of the galaxy about 30,000 light years from the center (img Source).