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Venus is the brightest and the second planet from the Sun. With apparent magnitude of -4.6, Venus can cast shadows. Venus never seems to endeavor far from the Sun because it is an inferior planet from the Earth. It has a maximum elongation, the angle between the Sun and planet as observed from the Earth, of 47.80, and reaches extreme brightness immediately before sunrise or after sunset (Gargaud, 2011). Venus shares some similarities with the Earth in that they approximately have the same size, gravity, and bulk composition. The Moon is the Earth’s natural satellite and the fifth largest satellite of a planet in the solar system. It rotates and revolves around the Sun on its axis and orbit respectively. The Moon’s diameter is approximately a quarter the earth’s diameter (Khan, 2002). In light of this, the study discusses the composition and atmosphere of Venus and the Moon, and NASA emissions.
Composition of Venus
The high surface temperatures have made it difficult for scientists to study the composition of Venus. Scientists on earth use the seismometers to research on the Earth’s composition. The seismometers can measure the magnitude of seismic waves that propagate through the earth (Pater & Lissauer, 2010). The inability of humans and spacecraft to survive the high surface temperatures contribute to the scanty information about the internal structure of Venus. However, scientists use the similarities between Venus and the Earth and other terrestrial planets to calculate the density of Venus (Seeds & Backman, 2009). Scientists have also affirmed that the internal composition of Venus is similar to the internal structure of the Earth. The only distinctive difference between Venus and the Earth is that Venus lacks plate tectonics. This explains why the internal part of Venus loses less heat as compared to the Earth. This is also a potential reason why Venus lacks an internally generated magnetic field.
Along with similar features of the Earth, Venus probably has the following: a core composed of metals; a mantle composed of dense rock; and crust composed of less dense rock (Zeilik, 2002). The core mainly comprises of iron and nickel as the Earth’s core. However, these metals have somewhat lower density, which indicates that the core also contains other elements such as sulfur. Scientific calculations reveal that the outer boundary of the core lies at approximately 3000 km from the center of Venus. The mantle lies above the core and forms the bulk of Venus’s size.
The temperatures of the mantle are likely to be similar to the Earth’s mantle despite the high surface temperature. Solid rock makes up the bulk of the Venus’s mantle though the material can flow or creep as glacial ice does. This allows the sweeping convective motions to happen (Zeilik, 2002). The decay of natural radioactive elements generates heat within the interior of Venus as in the interior of the Earth. Convection facilitates the transport of the generated heat to the surface of Venus. According to scientists, basalt forms the largest portion of the crust. The crust has a thickness of approximately 20-50 km as suggested by gravity data (Seeds & Backman, 2009). The convection currents in the mantle cause stress on the surface materials and tectonic deformation as observed in radar images.
The Atmosphere of Venus
The Venus atmosphere is much hotter and denser than the Earth’s atmosphere. Venus’s atmosphere comprises of opaque clouds made up of sulfuric acid (Khan, 2002). The opaque clouds explain why the surface of Venus is invisible from the Earth. The primary atmospheric gases of Venus are nitrogen and carbon dioxide. The entire atmosphere of Venus rotates the planet in four earth days, which is extremely faster than its sidereal day of 243 days. Strong winds blowing at a speed of about 100 m/s maintain the rotation of the Venus's atmosphere. The wind speed declines as the elevation from the surface reduces. The poles of Venus have anticyclonic structures called polar vortices that have an S-shaped cloud pattern (Gargaud, 2011).
Venus does not have a magnetic field. Ionosphere splits the atmosphere from the solar wind and outer space (Gargaud, 2011). The ionosphere lacks the solar magnetic field; thus, gives Venus a separate magnetic environment known as Venus induced magnetosphere. Scientific studies state that Venus’s atmosphere was identical to the Earth’s atmosphere with liquid water on the surface (Khan, 2002). However, the runaway greenhouse gases might have evaporated the surface water and increased greenhouse gases.
The atmospheric temperature and pressure at approximately 50 km to 65 km above the ground are closely similar to that of the Earth (Khan, 2002). This makes the upper atmosphere of Venus similar the Earth’s surface as shown by radar images of the solar system. The same way helium is a lifting gas on earth, oxygen is a lifting gas in Venus.
The Composition of the Moon
Scientists believe that just like the Earth the Moon’s internal structure comprises of layers. The lunar core is the innermost layer, and it forms about 20% of the Moon’s diameter (Khan, 2002). The lunar core consists of metallic iron and relatively small portions of sulfur and nickel. According to astronomers, the Moon’s core is partially in a molten state. The mantle lies above the core and forms the bulk of the Moon. The outer boundary of the Moon’s mantle or lunar mantle lies at a distance of 50 km below the Moon’s surface. The mantle comprises of minerals such as olivine, orthopyroxene and clinopyroxene. Additionally, the mantle is richer in iron than the Earth’s mantle.
The crust forms the Moon’s outermost layer and its inner boundary lies at a depth of 50 km below the surface. The crust is the most researched part of the Moon by scientists (Khan, 2002). The crust comprises of primarily silicon, oxygen, iron, magnesium, aluminum and calcium. In addition, other elements such as uranium, thorium, titanium, hydrogen and potassium normally appear as traces.
The Atmosphere of the mMoon
The Moon’s atmosphere or lunar atmosphere is a tiny layer surrounding the mantle. According to some scientific studies, the entire mass of the lunar atmosphere is approximately 10,000 kg (Khan, 2002). The lunar atmosphere originates from outgassing and debris kicked up by micrometeorite effects on the Moon’s surface. Outgassing is a resultant effect of radioactive decay processes that occur deep beneath the moon’s mantle. The formation of the atmosphere through impact as seen in the Moon is called “sputtering.”
Telescopic images of the Moon have revealed sodium and potassium in clouds surrounding the moon. NASA’s exploration identified polonium-201 and radon-222 elements (Gargaud, 2011). The Apollo astronauts identified traces of argon, helium, methane, nitrogen, carbon monoxide and carbon dioxide and oxygen. The lunar atmosphere also contains levitated moon dust. The dust is continuously jumping up and down off the Moon’s surface. The leaping action is due to the Ssun’s ultraviolet and X-ray radiation, which charges the atoms in the Moon’s soil. With the gain of positive charge, the atoms repel each other and engage in the leaping motion.
Past missions of NASA include the Apollo, Apollo-Soyuz Test Project and Exploration among others. Apollo was the first mission to land man on the Earth’s moon. The objective of the mission was to land man on the Moon and return to Earth safely. The mission set significant milestones in the human spaceflight. Having achieved the objective, Neil Armstrong and Buzz Aldrin landed on the Moon on the 20th of July 1969 and managed to return to earth safely. The current NASA mission is the Advanced Composition Exploration (ACE) conceived on June 19 1983. The main goal of ACE is to measure and compare the composition of different samples of matter such as the solar wind, corona and other interplanetary particles (Khan, 2002). The changing conditions in the solar cycle provide chances to achieve ACE’s goal. One of NASA’s future missions is the International Space Station. The goal of this mission is to launch an inhabitable artificial satellite. The satellite will precede the Salyut, Almaz, Skylab and Mir stations becoming the ninth inhabitable space station.
In conclusion, three distinct layers, which are the core, mantle and crust make up the internal structure of both the Moon and Venus. The core is the innermost layer, followed by the mantle and crust respectively. Venus’s atmosphere comprises of opaque clouds made up of sulfuric acid. The lunar atmosphere originates from outgassing and debris kicked up by micrometeorite effects on the Moon’s surface.