Milky Way. Computer artwork of our spiral galaxy, the Milky Way, seen from the side. This image is based on measurements of the galaxy's stars taken in infrared, radio and other wavelengths. Many of these stars are obscured in visible wavelengths by gas and dust clouds. These clouds are seen as dark areas in the arms (blue) that lie in the galactic plane. Our Sun is hidden in one of these clouds, about halfway out from the nucleus (yellow glow at centre). The colours seen here are due to the old, yellow stars of the nucleus and the hot blue light of the new stars of the arms. The Milky Way, around 120,000 light years wide, contains some 100 billion stars.