Milky Way. Artists impression of the Milky Way viewed from outside our galaxy. The Sun can be seen as the yellow star just to the left of lower centre. The Milky Way contains approximately 100 billion stars; these form a central bulge surrounded by a disk of swirling arms. The central bulge is about 10,000 light years thick whilst the disk is some 100,000 light years across. The Sun is about 33,000 light years from the centre. The Milky Way is revolving and the Sun, travelling at 270 kilometres a second, takes about 200 million years to complete one orbit. The Milky Way was formed when a gas cloud condensed after the creation of the Universe, the Big Bang.