Mercury's Surface

Mercury's surface is similar in appearance to the appearance of the Moon, showing plains and heavy cratering, indicating that it has been inactive for billions of years. Knowledge of Mercury's geology has been based only on the 1975 Mariner flyby and terrestrial observations, it is the least understood of the terrestrial planets. As data from messenger orbiter is processed, this knowledge will increase. For example, an unusual crater with radiating troughs has been discovered that scientists called "the spider" It later received the name Apollodorus. Names for features on Mercury come from a variety of sources. Names coming from people are limited to the deceased. Craters are named for artists, musicians, painters, and authors who have made outstanding or fundamental contributions to their field. Ridges, or dorsa, are named for scientists who have contributed to the study of Mercury.

Venus has an extremely dense atmosphere, which consists mainly of carbon dioxide and a small amount of nitrogen. The atmospheric mass is 93 times that of Earth's atmosphere, whereas the pressure at the planet's surface is about 92 times that at Earth's surface—a pressure equivalent to that at a depth of nearly 1 kilometre under Earth's oceans. The density at the surface is 65 kg/m3, 6.5% that of water or …show more content…
These plates are rigid segments that move in relation to one another at one of three types of plate boundaries: convergent boundaries, at which two plates come together, divergent boundaries, at which two plates are pulled apart, and transform boundaries, in which two plates slide past one another laterally. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation can occur along these plate boundaries. The tectonic plates ride on top of the asthenosphere, the solid but less-viscous part of the upper mantle that can flow and move along with the