THE SURFACE OF MERCURY
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he images brought back from Mariner 10 portrayed the surface of Mercury very similar in appearance and make-up to that of the Moon. Its landscape was weathered and smoothed by the constant bombardment of meteors, meteorites, and asteroids. The introduction of these foreign objects has created broad, flat plain regions, steep cliffs, and deep craters. When the planet was young and volatile, constant lava flows carved channels into its youthful exterior.
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he planet's crust consists of a thin covering, about 500 to 600 kilometers, of minerals called silicates (in the form small particles). This causes the surface to reflect about six percent of all sun light it receives. Underneath the crust lies a dense core of iron, about 1800 - 1900 kilometers, that is relatively larger than the Earth's and probably comprising the majority of the planet. A small percentage of the core is in a liquid state, but unlike the Earth, Mercury has no plate tectonics. There are a few interesting topographical features that are located on the planet's surface.
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he Caloris Basin is one of the largest features on the planet, it is about 1300 kilometers in diameter. It is thought that the basin was created by a large impact early in the history of the universe. Debris from this collision was sent as far as 800 kilometers across the planet. The strange marks on the opposite side of the planet are thought to be caused by this impact.
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t might not be apparent from the pictures of the planet, but the majority of its terrain is made up of a broad, relatively smooth plains region. Scientists divided them into two main categories, intercrater plains and smooth plains. Intercrater plains consist of areas with craters less than 15 kilometers in diameter, while smooth plains are younger and with fewer craters yet. These areas may have been worn down by ancient volcanic activity, but more probably were caused by the ejecta from the larger crater causing impacts.
