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Our understanding and our modern perception of our solar system, the Milky Way, has been drastically reshaped from the corresponding perception of only a few hundred years ago. Our Solar System, the Milky Way is probably about 4 - 5 billion years old. Only in the last 400 years or so have we realized that the earth is not the "center", and that in the Universe alone there is an immense 200 billion "Suns" in a galaxy like our own. Although the origin of the solar system is uncertain, most scientists believe that it began to develop about 4 1 / 2 billion years ago from a large cloud of gas and dust. The Sun is the largest celestial body in the Milky Way Solar System, with more than 1. 000 times the mass of everything else added together.
It's the Sun's huge gravity that keeps all of the nine planets, their moons, the asteroids, the comets, and the dust between the planets all orbiting the Sun. It would take more than 100 Earths placed side-by-side to go from one edge of the Sun to the other and can hold 1, 3 million Earths The Sun is a star, and shines because it generates light and heat by nuclear reactions in its core. Mercury even though 36 million miles away from the sun, is still closest to the sun out of all the other planets and is difficult to observe from the Earth because it rises and sets within two hours of the sun. Mercury's surface has several different types of terrain. Some regions on Mercury are heavily created, suggesting that they are very old surfaces that were probably formed about 4 billion years ago.
Between these regions are areas of gently rolling plains that may have been smoothed by volcanic lava flows or by accumulated deposits of fine accumulated a large number of impact craters. Elsewhere on the planet are smooth, flat plains with few craters. These plains are probably younger and volcanic in origin. The largest impact basin on Mercury, Colors, is about 800 miles across and is surrounded by mountains that rise to heights of about 1. 2 miles. Mercury the eighth largest planet is very dense and has a magnetic field that is about 1 percent as strong as Earth's, which suggest the existence of a core composed of iron and nickel and constituting about 40 percent of the planet's volume. The surface gravity is about one third as strong as Earth's.
A thin atmosphere of hydrogen, helium, potassium, and sulfur surrounds the planet. Radar images taken of Mercury in 1991 show what are considered to be large ice patches at the planet's North Pole. Mercury has no satellites, but rotates on its axis three times for every two revolutions around the sun and has a more elliptical orbit that do most other planets. Temperatures in terms of the Kelvin scale, an absolute temperature scale in which 0 K is the lowest possible temperature, corresponding to - 459. 67 degrees F.
Surface temperatures on Mercury range from about 675 K at "noon" to 100 K just before "dawn. " (temperatures of about 295 are comfortable for humans) It takes almost 59 Earth days for Mercury to complete one rotation about its axis, but the time between one sunrise and the next is 176 Earth days. The next from the sun is Venus. Venus is the most brilliant natural object in the nighttime sky, after the moon. Venus is the closest planet to the Earth and is also the most similar to Earth in size, mass, and density. These similarities suggests that the two planets may have had similar histories. Venus rotates once every 243 days in retrograde motion, or apparent backwards motion.
Venus is very difficult to observe because its surface is completely obscured by thick layers of dense clouds. The atmosphere of Venus is mainly composed of carbon dioxide, with droplets of sulfuric acid in the upper clouds. The upper atmosphere moves rapidly, completely circling the planes in four days, while the winds at the surface are gentle. The surface temperature is approximately 750 K, even hotter than Mercury's noon temperatures. The large amount of carbon dioxide in Venus' atmosphere accounts for the extremely high temperatures near the planet's surface and the greenhouse effect that traps and absorbs the sun's heat. Because of the clouds, only 15 % of the sun's light reach the planet's surface.
Days on Venus are dim and overcast. Some places on Venus the surface has been severely fractured and folded by stress caused by the convection of the Venusian mantle, the part of the planet just above the core. The highest mountain on Venus, Maxwell Montes, is about 7 1 / 2 miles high and might possibly be a volcano. After Venus is our planet, Earth. Earth is the 5 th largest planet and 149, 600, 000 km from the sun. Earth is divided into several layers that have distinct chemical and seismic properties.
The crust varies considerably in thickness, it is thinner under the oceans, thicker under the continents. The inner core and crust are solid; the outer core and mantle layers are plastic or semi-fluid. The various layers are separated by, which are evident in seismic data; the best known of these is the discontinuity between the crust and upper mantle. Most of the mass of the Earth is in the mantle, most of the rest is in the core. The core is probably composed mostly of iron though it is possible that some lighter elements may be present, too.
Temperatures at the center of the core may be as high as 7500 K. The lower mantle is probably mostly silicon, magnesium and oxygen with some iron, calcium and aluminum. Unlike the other planets, Earth's crust is divided into several separate solid plates, which float around independently on top of the hot mantle below. There are (at present) eight major plates and twenty more small plates. The Earth's surface is covered with 71 % water, which is also responsible for most of the erosion and weathering of the Earth's continents. Earth's temperature is relatively stable.
The atmosphere of the Earth is 77 % nitrogen, 21 % oxygen, with traces of argon, carbon dioxide and water. The greenhouse effect raises the average surface temperature about 35 degrees C above what it would be without the oceans would freeze and live we know it would be impossible. Earth only has one natural satellite, but thousands of small artificial satellites have also been place in orbit around the Earth. Mars, the fourth planet from the Sun, is also the seventh largest. Mares are 277, 940, 000 km from the Sun.
Named after the Greek god of War, Mars has been known since prehistoric times as an object of great interest to astronomers. Unlike Venus, Mars generally has no obscuring layer of clouds. In addition, it passes relatively close the Earth in its orbit. Mars is about half the size of the Earth and its atmosphere is composed mostly of carbon dioxide. The temperature at the planet's surface varies widely during the course of a Martian day, form about 190 K just before dawn to about 240 K in the afternoon. At the center of the planet is probably a small iron or iron sulfide core.
If Mars has a magnetic fi...
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Research essay sample on Billion Years Ago Carbon Dioxide
