Resemblance to the Moon 

The surface of Mercury is in many ways similar to the lunar terrain. It is heavily cratered with no plate tectonics, it has plains of dust-covered hills from the constant impact of meteorites, and it has huge multi-ring basins along with fault cliffs and many lava flows. If one would gaze out over the horizon of Mercury, he would notice that the Sun appeared to be two and a half times larger than on Earth and be able to make out two planets, the blue Earth and the creamy colored Venus.

The surface of Mercury also has huge escarpments hundreds of kilometers wide and some at least three kilometers high. One would also see great curved cliffs or lobate scarps formed from cracking of the surface due to the inner iron core of Mercury cooling.

Other features of the wrinkled crust include escarpments that extend through the rings of concentric mountains and other features on the landscape that were formed by the compression of the planet. It is calculated that the surface area of Mercury shrank about 1 km in the planet's radius. That's about a 0.1% decrease.

The craters of Mercury range in size from 100 to 1,300 kilometers and come in a great variety of shapes and distinctive features. The younger craters have thin, sharp rims while some of the larger craters have bright rays that indicate heavy impact. The older craters have been eroded down by collision with small meteorites.

Besides the many craters on Mercury, the majority of the surface is covered by smooth plains that resulted from ancient volcanic activity and the scattering of ejecta from asteroid impacts. Much of the plains are old as evidenced by the heavily cratered areas from the bombardment of foreign objects, while some plains are relatively younger. Scientists have classified plains into intercrater plains and smooth plains. Intercrater plains are ones more cratered. They are also less than 15 kilometers in diameter. Most likely, intercrater plains were formed by lava flows. The smooth plains are generally younger had have less craters. There is some evidence of recent volcanic activity on Mercury but more research will need to be conducted.

Although Mercury is similar in appearance to the Moon, it is much denser. It is only second to Earth in its density being 5.43 g/cm³. Mercury's iron core is larger than Earth's and makes up most of the planet. However, if it weren't for Earth's gravitational compression, Earth would be less dense than Mercury.