Pangaea and the arrival of the Oceans
The Milky Way is over 100,000 light years across and has a supermassive Black Hole at its central nucleus.
The gravity system which holds the Solar system together cannot hold the mighty Milky Way together especially when you consider that it is moving at the incredible speed of 900,000 mph towards the constellation of Virgo.
The Milky Way once again shaped like a disc, however, take a fishing float at the centre and it is in flight mode at 35° to this.
The solar system however is making its way around the Milky Way at 500,000 mph.
The core or nucleus of the galaxy is surrounded by a bulge of stars that grows denser closer to the centre. This forms an ellipsoid of about 15,000 by 6,000 light years, the longest dimension lying along the plane of the Milky Way.
Young stars etch out a spiral pattern and it is thought that they radiate from a bar.
The thickness of the Milky Way is about 2,000 light years. The Sun lies about 25,000 light years from the centre. The stars in the bulge have the highest orbital rates. They can travel hundreds of light years above and below the plane of the Milky Way.
Within the disc, stars stay mainly in the plane of the galaxy as they orbit the galactic centre.