The Formation of Mercury 

According to many scientists, our solar system formed about 4.5 billion years ago. A nebula (cloud of gas) condensed into early forms of the planets. As each planet increased in its gravitational force the remaining dust and matter finished forming the planetary bodies. This was followed by a period of intense bombardment by foreign objects such as asteroids, meteors and comets. Mercury's formation involved several steps.

1. The section of nebula that formed Mercury formed a dense metallic core with a thin silicate crust on the surface.
2. As asteroids bombarded the surface, internal lava flowed out and formed a new crust.
3. Over time, Mercury's core cooled down and shrunk. As a result, the outer crust cracked.
4. Another wave of lava ensues, covering the older crust.
5. Additional bombardments of smaller meteorites formed a dusty surface known as the regolith. On occasion, large asteroids would strike Mercury creating bright rayed craters.

Aside from occasional asteroids, Mercury will remain generally unchanged for centuries.