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11.9
The inner planets
 
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11.9.1 Mercury  
  Mercury is 4,878 km in diameter about 40 percent of that of the Earth- and of high density with a large core consisting mainly of iron, partly molten. The surface of Mercury is very hot, varying at midday according to the distance from the Sun from 285 degrees C to 415 degrees C. Because of the lack of blanketing atmosphere the night-time temperature is very low down to about -175 degrees C. There is very little atmosphere because such daytime temperatures excite any atmospheric particles to a level of energy that allows their escape from the very low gravity of the planet. Mercury has a magnetic field that, although much lower than that on Earth is still strong enough to deflect solar wind, streaming past it.  
  The American Mariner spacecraft passed close to Mercury in 1974 and 1975 and showed that the surface is covered with impact craters very similar to those on our Moon. The largest crater, named the Caloris Basin because it is one of the hottest areas (from the Latin calor "heat') of the planet, is about 1,300 km across. The Sun is directly over this crater when Mercury is at its nearest point to the Sun (perihelion). The floor of the Caloris basin is broken up into ridges. Mercury is not so heavily cratered as the Moon and has extensive plains free from cratering.  
11.9.2 Venus  
  12,100 km in diameter and 108 million km from the Sun. No moons, rotates once in 243-4 days, orbits the Sun, once in 224.7 days.  
  The second minor planet, in order outwards from the Sun, is Venus, sometimes known as the "morning' star or "evening star" because it is clearly visible from Earth around sunrise and sunset.  
  Because of its dense, silvery atmosphere, Venus is highly conspicuous as the brightest object in the night sky after the Moon. It is a solid globe 12,104 km diameter and most closely resembles Earth in size, mass and distance from the Sun.  
  Its orbit around the Sun is almost circular with a radius of about 108 million km, and one orbit takes 225 Earth days, a Venusian year. Unlike the other planets, Venus rotates in the opposite direction to that of the Sun's rotation- probably because of the gravitational pull on it of the Earth. This retrograde rotation is, however, very slow taking 243 Earth days. The Venusian day is thus longer than its year.  
  The atmosphere is dense and hot and consist largely of carbon dioxide with swirling vapor clouds of sulphuric acid, hydrochloric acid and hydrofluoric acid. This dense atmosphere prevents loss of heat and maintains the surface temperature of the planet at a constant 475 degrees C- hot enough to melt lead. It also exerts a pressure at the surface of the planet some 90 times that of the Earths atmospheric pressure.  
  The surface of Venus appears to be between 100 million and 1 billion years old and is covered with craters, folded mountain ranges and areas of lava flow and faults, indicating a history of turbulent volcanic activity and impact from large meteors. There are features resembling river beds- probably caused by flowing lava and flat circular areas without definite craters.  
11.9.3 Earth  
  The Earth is 12,756 km in diameter and orbits at an average of around 149 million km from the Sun. Our Earth is the third planet from the Sun. The planet is inclined on an axis approximately 23.5 degrees to the Sun and rotates on its axis on average every 23 hours 56 minutes. The planet itself orbits around the Sun on average around once every 365.24 Earth days.  
  Our planet has one moon, with the name Moon. It is approximately 3,475km in diameter (0.273 times the size of the Earth) and orbits at an average distance of around 384,199 km from the Earth (about 30.1 times the diameter of the Earth). The moon orbits our planet at the equatorial plane of the Sun and in the same anti-clockwise motion of the Sun to the Earth. The Moon orbits in relation to our planet once every 29.5 days ( a lunar month). The Moon itself rotates on in its axis once every 27.3 days. However, since the Moon's rotation of itself and rotation of the Earth approximate the same period, the moon tends to present the same hemisphere (or face) to use and therefore we never see the 'dark side.  
  Of particular interest is the age of the Earth and the Moon. Rocks returned by US astronauts have shown that both the Earth and the Moon are approximately the same age. Therefore, unlike the giant planets of Jupiter, Saturn, Uranus and Neptune which appear to have "captured" via gravity many of their moons, the Earth's moon was formed during the same birth time of the Earth. Its major surface difference can then be explained by the higher ratio of meteorite and asteroid hits and therefore dust and debris settling with the Moons gravity over hundreds of millions of years.  
  While the Earth is significantly smaller that the Sun, our planet is mostly an Iron (26 atomic number), Silicon (14 atomic number) and Oxygen (8 atomic number) planet versus Hydrogen (1 atomic number). In terms of surface, the Earth is predominantly covered by oceans of water molecules (around 70.8%). Only around 149 million square kilometres is land.  
  What is not fully comprehended is what substance makes up the core of our planet. Interestingly, speculation over centuries believed that the core of our planet was made of something precious like Gold.  
  Given our understanding of the formation of star systems via nebulae, the core and inner most regions of the Earth should by rights be made of the most basic of material from the explosion of the nebulae, while the regions closer to the surface are more complex in atomic number.  
  This is contrary to contemporary science that believes the atomic weight of material closer to the core should increase. As we know this does not make sense in terms of the logical creation of the planet.  
  We conclude therefore that the core of the Earth is made up of the most valuable substance in the Universe (which incidentally is not Gold) but super compressed hydrogen. It is this core that determines why the Earth orbits at the position it does relative to the Sun, not the layers of more complex atomic structures covering the core.  
  We explain this by "likeness attracts likeness". Our likeness is our super dense, super pressured inner core of hydrogen that incidentally is the reason why our planet remains relatively stable in structure (the pressure outwards of the hydrogen, compensates for the pressure inwards of the higher elements).  
  Rotation and orbit speed differentials  
  Contrary to popular understanding, the rotation and orbital speeds of the Earth are not constant. The Earth's orbit speed increases during two periods of the year December to March and from June to September. In contrast, there are two periods when the motion of the Earth around the Sun slows down from March to June and from September to December.  
  Weather and Seasons  
  The Earth is closest to the Sun at two periods called the Northern Spring Equinox (20-21st March) and the Southern Spring Equinox (20-21 September). This is called Perihelion and the distance from the Sun is around 147 million km.  
  There are two periods where the Earth is furthest away from the Sun the Northern Summer Solstice (20-21 June) and the Southern Summer Solstice (20-21 December). This is called Aphelion and the distance from the Sun is around 152 million km.  
  Contrary to popular science, it is the effect of exposure to particles from the Sun, combined with the relative position of the shockwave front that explains the different weather effects and temperatures on the planet (as explained earlier in this chapter).  
  Calendars and dates  
  Due to the historical usage of (a modified) yearly calendar first implemented by Roman Emperor Julius Caesar around 45BC, all Western calendars are continuously out-of-sync with the true cycle of the Earth.  
  In 3 years out of 4, almost all societies of humanity use a 365 day calendar. In leap years (the 4th year), the error is "corrected", by adding an extra day to account for four years of an extra .24 days. This makes leap years the only years that get close to providing an accurate measure of the Earth's orbit cycle around the Sun.  
  The most accurate calendar used by an society to measure the years appears to be the Mayan Civilization (up until 600AD). By calculating the year into 18 months of 20 days, plus a 5 period of "clean up", their calendar was accurate to within a few minutes, even after thirty to forty years, compared to our present day calendars that continue to slip and slide out of date by some multiple hours.  
11.9.4 Mars  
  6800 km in diameter and 228 million km from the Sun. Two moons, rotates once in 25 hours, orbits the Sun once in 687 days.  
  Known as the 'red planet', because of the prominence of iron oxide (rust) in its soil and dust, Mars is closer in its characteristics to the Earth than any other planet. Its diameter is about 6,800 km just over half that of Earth- but its mass is only about one tenth that of Earth. The Martian year is equal to 1.88 earth years, and the day is only 37 minutes longer than the Earth's day.  
  Both planets have a titled axis of rotation so that different amounts of sunlight fall on each hemisphere at different times of the year, causing seasonal weather changes. The difference between the Martian summer and winter is, however more extreme than on earth because its orbit round the Sun is more elliptical and the distance from the Sun varies from 206 million km to 249 million km.  
  This difference of 43 million km means that the southern hemisphere of Mars receives 40 percent more solar radiation when nearest to the Sun (perihelion) than when furthest away (aphelion), giving a warm summer and a cold winter.  
  The northern hemisphere has a cool summer and a mild winter. temperatures at the equator can range from 10 degrees C to -75 degrees C. The distance of Mars from Earth varies from 50 million km to 100 m km and the closest approach to Earth occurs every 15 or 17 years.  
  The Martian atmosphere is very thin- about one per cent of that of Earth- and consists mainly of carbon dioxide with some nitrogen and argon along with traces of oxygen and water vapor The atmospheric pressure is very low.  
  The surface details of Mars have always been difficult to make out because optical observation have to be made through two atmospheres, but thousands of pictures taken by Mariner and Viking spacecraft landed on Mars in 1976 and took many close up photographs of the rock-strewn surface of dusty reddish plains.  
  There are many inactive volcanoes, one 24 km high; large numbers of flat bottomed craters from meteorite impacts, especially in the southern hemisphere a huge rift valley near the equator running east for 3,000 km and many smaller valleys and canyons. That these were caused by water erosion is by no means implausible. At each pole is white cap of snow, ice and frozen carbon dioxide that changes size with the seasons, reaching as far as 45 degrees latitude in the wintertime. Frosty crater rims protrude upwards through the snow.  
  Most scientists believe that there is considerable water on Mars in the form of a permafrost. At various periods in the past, floods of water have occurred. No liquid water can, however exist today as, because of the low atmospheric pressure, it would immediately vaporize and circulate to the poles where it would freeze. The darker areas on mars sometimes appear even darker when the polar ice caps regress.  
  Dust storms are common on Mars and these sometimes cover almost the whole planet in a red haze. No conclusive evidence of any kind of biological activity or organic chemical compounds has ever been found on Mars.  
  Mars has two satellites (moons) Phobos and Deimon- discovered in 1877 by the American astronomer Asaph Hall (1829-1907) during the same approximation to Earth of Mars in which Giovanni Schiaperelli drew his famous map.  
11.9.5 The inner asteroid belt  
  The inner asteroid belt is located around 350 to 650 million km from the Sun. It contains some millions of meteorites, averaging between a few metres and up to 2 km in diameter. The asteroid belt is relatively stable, largely due to the interaction of the Sun's particle fields and Jupiter's particle fields effectively "parking" debris around this region.  
     
     
     
     
 
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