recent as 1906 in Siberia. This was either a small asteroid or the remnants of a comet. Instead of impacting the ground (as in Arizona), this one exploded above the ground in what is called an air burst explosion. The devastation in Siberia was not unlike that of the Hiroshima atomic bomb of World War II, which was detonated above the surface of the Earth. The Siberian explosion leveled over twelve hundred square miles of forest, but did not leave an obvious crater.
Although the impact of an asteroid is a rare occurrence on this planet, meteorites are a different story. The Earth is hit by meteorites about once every ten hours. Of these impacts, very few meteorites are actually found as the majority are over water or uninhabited areas of the planet. A celestial object (that impacts Earth) less than fifty meters in size is considered a meteorite and objects fifty meters or larger are asteroids. A forty nine meter meteorite would cause massive damage in a populated area, with extensive loss of all life within a fifty mile radius and extensive damage for hundreds of miles beyond the impact site. Fortunately, most objects that impact Earth are smaller than a baseball (most are pea sized).
Meteorites come in three basic categories; aerolites, siderites and siderolites. Aerolites are comprised of stone and rocky substances, such as what the Earth was originally made of, these are the most commonly found meteorites on Earth and probably originate in the asteroid belt between Mars and Jupiter. Siderites consist of mostly metals or alloys of metals, IE iron, copper and nickel. Siderolites are comprised of both stone and metals and are the rarest and most valuable of all meteorites found. Some avid 'hunters', have amassed sizable fortunes hunting and finding meteorites throughout the world.
In modern times there has never been a report of any person being killed by a meteorite, although there have been several close calls, IE a meteorite coming through the roof of a house, and a vehicle hit by a baseball sized meteorite. The only known fatality was a very unlucky dog.
Other than a natural catastrophic event such as an erupting volcano, an earthquake, severe storm, or hit by a celestial object, mankind has control over his own destiny to an extent and is the Earth's guardian. If the race of Humanoids on this planet survive from themselves and any impending natural doom, they will have long since learned the secret of inter-stellar travel and the death of this solar system will be of no consequence to them. We will have colonized other host worlds and continue life as has other civilizations throughout the Universe.
Mars at one time had a similar type atmosphere as Earth has today, only with slight variances in its composition. The planet also had a dynamo creating protective lines of flux, but because Mars is a much smaller planet than Earth (less than half the diameter of Earth) and combined with its greater distance from the Sun, its core started to cool about one billion years ago. This loss of a protective barrier (slowly over two hundred fifty million years) caused radiation to penetrate its atmosphere and eventually vaporize the liquid water on the planet's surface, although it should be said, Mars still retains water beneath its surface in the form of ice.
Mars still has magnetic areas (strong spots) dotted around the planet, these magnetic areas are probably the remnants of strongly magnetized fields of rock and iron. These pockets of magnetic rocks are the only evidence geologist have that Mars had a magnetosphere at one time. The only way indigenous metallic rocks can be magnetized is by the presence of a strong magnetic field, much the same way iron can be magnetized on Earth with the introduction of a strong magnetic field.
Mars is sometimes referred to as the Red Planet, the red appearance comes from iron rust. The high iron content of the planet's makeup (like the Earths abundance of iron) oxidized over time leaving the red hue we see today. The 'rust' can only happen in the presence of water and oxygen, this fact is further proof of the existence of liquid water and of an ancient atmosphere containing oxygen similar to that of Earth.
Today the atmosphere of Mars is comprised primarily of carbon dioxide, 95%, with the remaining five percent consisting of; argon, nitrogen and trace amounts of oxygen. The usual appearance of the sky is a reddish hue, the result of surface dust in the atmosphere caused by severe storms on the surface of the planet. Dust devils dance across the surface of the planet carrying the loose powdery surface high into the thin atmosphere.
Occasionally the storms will subside and the sky will be a dark blue color, the result of a mostly carbon dioxide atmosphere without the dust particles. The density of the atmosphere is about one hundred times less than that of the Earth, making it very thin and not capable of retaining the warming radiation of the Sun.
The large presence of carbon dioxide in the atmosphere is probably the result of massive volcanoes of the past, the largest known volcano in the solar system is to be found on the surface of Mars. Olympus Mons is approximately seventeen miles high with a base diameter of over three hundred fifty miles. The size of this monster is the result of a 'hot spot volcano', caused by the lack of movement of tectonic plates, unlike most volcanoes on Earth.
Examples of a hot spot volcano on Earth would be Yellowstone park in Montana, or another in the Hawaiian Islands. Volcanoes on Earth do not reach the height or size of Martian volcanoes because, although a hot spot volcano on Earth may erupt for a similar period of time as the ones on Mars, the plates of the Earth move the crust of the planet, thus shifting the location of the volcano on the surface, resulting in a smaller buildup in any one spot. It has been estimated that the volcanoes on Mars have been inactive between fifty million and two hundred million years. The core and mantel of the planet have cooled to the extent that an active volcano is very unlikely today, if not impossible.
Water on the planet (required for all life forms as we know them) is in the form of polar ice, especially in the northern hemisphere. In the summer months (seasons on Mars are about twice as long as Earths) the North pole's ice cap is clearly visible. The South pole's ice cap is believed to be primarily dry ice (carbon dioxide ice) rather than frozen water. In the winter months (about minus two hundred fifteen degrees Fahrenheit) the North pole is also covered with dry ice as the carbon dioxide atmosphere snows on the pole.
Some scientist believe there may by liquid water under the surface of the equatorial regions. They believe the compact sandy formations of the planet would have been worn down over the ages by the winds (up to two hundred miles per hour) and constant storms on the planet's surface if they were not held together by some form of water. The surface temperature in the equatorial region, as much as sixty eight degrees Fahrenheit in the summer months during daytime hours, could warm the surface and underlying water ice enough to make it liquid.
The question has always been; 'Is there life on Mars?' In the late nineteenth century, H. G. Wells wrote the novel, "War of the Worlds" in which the Earth was invaded by Martians. In the early twentieth century, Orson Wells (no relation) broadcast the story over the radio, causing ensuing panic as the populous believed it to be a real invasion. Of course this was just the fictitious account of the H.G. Wells novel, but people on this planet are very easily misled, such as in religion which we will discuss in later chapters.
It is not a question of whether there is life on Mars, but rather what kind of life is on Mars today? Forms of life can exist in extreme environments and Mars is not that extreme of a world. You are not going to find fossilized remains of mammals on the planet, but there is still currently microscopic life forms on the planet!
Mars is the most explored planet (other than Earth) by mankind in our solar system. The first artificial satellites were sent in the early 1970's and since there has been a flood of satellites and landers on the surface. With the successful landings of the Mars rovers (Spirit and Opportunity), everyday man on Earth could watch as we explored another world for the first time with video sent back to Earth. Currently there are plans to return to the Moon by 2020 (now in doubt) and use the resulting base on the Moon as a launching post for manned missions to Mars (as of this writing, the Moon m
ission is still being debated and may actually be many years in the future).
The knowledge of mankind on this planet has come a long way in just the last one hundred years, when you contemplate that we were barely able to fly in our own atmosphere, let alone the possibility of traveling to and exploring another world before the Wright brothers inaugural flight at Kittyhawk.
Mars has two satellites (moons), Phobos meaning fear and Deimos meaning dread, both named after characters of Homer's Iliad. Both of these moons are irregular in shape and both are very small. These moons may be merely asteroids from the belt of asteroids between Mars and Jupiter that have been 'caught' in the gravitational pull of the planet. Phobos orbits closer to the planet than any other moon in the solar system (about three thousand miles above the surface). The orbit of Phobos is so close to the planet in fact, it is nearing the Roche limit (15) and its orbit will eventually erode to the point that it is torn apart by the gravitational pull of the planet (probably not for millions of years). It will be determined in future years (through exploration) that Phobos is not solid like almost all other