Our galaxy, the Milky way, is a spiral galaxy.The sun occupies a peripherical position.

The centre of our galaxy, which is not visible in the optical because it is hidden by dust, is a powerful emitter of radio waves.  The study of these emissions indicates the existence of a strong magnetic field and relativistic electrons.

Fig. 1: Radio image of the centre of our galaxy at various wavelengths. (Credit: Lang, Morris, Roberts, Yusef-Zadef, Goss, Zhao)

It is thought that at the centre of our galaxy there is a massive black hole, with a mass at least a million times greater than that of the sun.