presence of liquid water, a sustainable atmosphere, and moderate temperature. These three elements must also be in combination with a protective magnetic field that is able to sustain and retain the atmosphere that protects the planet from the star's solar wind (radiation). I might point out that not all galaxies have Earth-like planets, while others like our own Milky Way Galaxy have an abundance of habitable planets.
Other than being in the habitable zone, another major determining factor of a habitable planet is in the physical makeup of the galaxy its self. Some galaxies simply contain too much radiation for a habitable planet to exist, even if there are planets in the area we call the habitable zone of a star. Whether the radiation is from a pulsar (12) or several giant stars going supernovae in the galaxy, there is simply too much radiation to sustain life forms as we know them. If there were a pulsar directed at the Earth within fifty light years of the planet to emit this type of radiation, it would surely destroy our fragile atmosphere (our atmosphere only extends a mere sixty two miles up), ecosystem and most life forms except for a few bacteria and simple organisms as the DNA of most all life forms is altered or destroyed to the point of not being able to reproduce when exposed to excessive amounts of radiation. It is possible that a pulsar would only emit an electromagnetic pulse (EMP) towards the Earth, but that in its self would change our standard of living on this planet tremendously as all electronics would be rendered inoperative.
As stated before, there are several factors involved for a planet to be habitable, but the foremost is that a planet reside in the habitable zone. Planets in this temperate zone may have a seasonally adjusted (surface) temperature range between minus one hundred sixty degrees Fahrenheit, to two hundred degrees Fahrenheit (Earth has a temperature range between minus one hundred thirty and one hundred and thirty nine degrees Fahrenheit).
The aforementioned temperatures may seem extreme given our very moderate climate here on Earth (especially in areas most populated), but animal and plant life can adapt and flourish at the aforementioned temperatures, as evidenced by the extremes on our own planet. Scientist were amazed to find creatures living in what we think to be uninhabitable areas on this planet. For example sea life living in the extremely hot plumes released from volcanic vents at the bottom of the ocean. Some of these vents emit gases at a temperature of over two hundred degrees Fahrenheit, and this life is living in what we consider a poisonous environment unable to sustain life. Life has learned to adapt and survive in these extremes, albeit mostly simple life forms. Although we believe all life is based on a phosphorous base, other life forms can and do exist with a different chemical base.
If life can adapt to the extreme conditions on this planet, it is only logical to assume life can adapt to other world's extreme conditions also. Now I am not saying mankind can adapt to these extremes, but simply that lower forms of life can and do adapt to temperature and chemical makeup extremes. In our solar system only two planets reside in the habitable zone, the planets Earth and Mars (habitable maybe six hundred fifty million years ago).
The planet Earth is not unique in its ability to sustain higher life forms, but the planet is unique in the Universe. Just like no two finger prints are the same, no other planet in the Universe is exactly like the Earth. The planet Earth is truly a jewel, just one of many trillions of planets in the Universe, we should feel very fortunate and privileged to be able to call it home.
The planet Earth is well past its midlife as a habitable planet, a little over four billion six hundred million years old and will last between one and a half and two billion years as a habitable planet (barring a catastrophic event). That is when the Earth will have cooled enough internally to lose its protective magnetic field as the dynamo turns off. When the Earth's magnetosphere is gone, our atmosphere will be bombarded by the solar particles and will just simply evaporate into space. With the loss of the atmosphere, all surface water will also be lost very quickly, (over a period of about three hundred thousand years).
Scientist here on Earth believe the planet will last another four or five billion years (until the death of the Sun). That is true, but not the planet as we know it today, Earth will spend the last two or two and a half billion years as a 'dead planet', similar in makeup as Mars is today. Scientist are correct in their belief that the Earth will be encompassed and vaporized by the Sun when the Sun runs out of fuel and begins to lose its mass and radiation into space at the end of its life cycle.
Two billion years is only a best case scenario for a habitable Earth. As throughout all of the Universe, there are rogue masses traversing in and around the galaxies. It could be a comet, an asteroid, a free black hole (54), or even another galaxy on a collision course with the Milky Way. Actually the Andromeda Galaxy (which is much larger than the Milky Way) is headed towards the Milky Way Galaxy and the two will eventually merge in a cataclysm of tremendous proportions to evolve finally into a much larger single galaxy with new beginnings (not for a few billion years). Currently there are mini-galaxies merging with our Milky Way Galaxy, but with very little consequence as the distance between stars is tremendous.
Any of these scenarios could impact the Earth with catastrophic results for the inhabitants If the Earth does escape a celestial malady, the ability of the Earth to be a habitable planet will come to an end when the magneto's magnaflux of this planet is destroyed.
The Earth has a core comprised primarily of iron which is encircled by molten lava consisting of minerals and metals revolving around it. This (magneto) is what creates the field of magnetic flux (13) that encircles the planet. Currently the lines of flux come out of the South pole and reenter the Earth at the North pole. This bubble of magnetic energy, called the magnetosphere, deflects most of the solar radiation around the planet and far off into space.
This magnetic field restricts excess radiation that is deadly to almost all life on this planet, radiation not only from our own Sun but also the natural radiation created by the nascency (14) of the Universe, that radiation which traverses throughout all the Universe. The magnetic protective shield along with gravity is what holds our atmosphere together and gives us protection from excess radiation.
As stated, without a strong magnetic field our atmosphere would simply dissipate and be lost into space. The loss of our atmosphere would quickly deplete the liquid water on the planet and the surface would become a cold (without an atmosphere to hold the warm radiation on the planet) and desolate place devoid of life, except for certain forms of bacteria and some subterranean life forms.
Of recent times there has been a lot of talk about global warming and what we humans have done to perpetuate this situation. The burning of fossil fuels has put trillions of tons of carbon dioxide into the atmosphere, but in actuality, modern mankind has only contributed about twenty percent to the temperature change in the last two hundred years. The Earth is naturally going through a cycle of climate change, and even with mankind's reduction of carbon into the atmosphere the trend will continue, although at a slower rate.
Climate change means that the Earth's climate we are familiar with today will change worldwide over time. Some areas of the planet will be warmer than present while other areas will be cooler, at the same time the annual rainfall will change drastically in different areas on the planet (as in the Hourglass Effect). Worldwide, the average global temperature has been increasing over the last one thousand years, but this increase is mostly due to the natural evolution of the planet as the axis and our position in the Milky Way slowly changes.
Recently, some areas such as in the northern hemisphere, saw record low temperatures, while parts of the Asian continent have been in a drought for several years. The previous decade (2000-2009) was the warmest average worldwide temperature ever recorded. Climate change does not happen overnight and may take several hundreds of years before there are significant changes. The doubters of today's world (as to climate change) will long be gone before a new era has fully arrived.
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The release of man-made chemicals into the atmosphere has helped to deplete the ozone layer and allowed substantial amounts of radiation to penetrate our atmosphere, especially at the poles. The aurora borealis is actually solar radiation penetrating the weakened ozone layers at the poles, illuminating our atmosphere as the molecules are ionized by the excess radiation. The northern lights, as they are sometimes called, have been visible further south in recent years and will continue to be more evident in North America (all of the northern hemisphere) as more radiation seeps through.
The increased radiation, along with the natural climate change of the planet has started a warming of the polar oceans and atmosphere as evidenced by the loss of ice in both polar caps. Mankind can still facilitate a change that will slow the depletion of the ozone layer, but he cannot wait until it is beyond repair (recently the hole in the ozone layer at the poles has diminished in size). The worldwide dependence on fossil fuels must be negated in the next three or four decades if mankind is to continue to flourish on this planet without doing irreparable harm to the ecosphere.
The Human population of this planet do have a responsibility to ensure we have no negative effect on the natural progression of evolution on this planet. Mankind is encouraged to use the natural resources of this planet for the advancement of civilization, (I hesitate to use the word civilization, there is not much 'civil' about this population), but not to the detriment of the planet's Eco system. There is a fine line between progression and destruction. I find it utterly amazing there are people who deny mankind's adverse effects on the ecology of the planet. Pull your head out of the sand!
The energy needed for the advancement of this civilization can be obtained through 'clean' means provided by the Earth and its environment. Wind, solar, wave and even nuclear energy are appropriate forms of 'clean' energy. The use of carbon based fuels, such as petroleum and coal, only pollute our atmosphere to the detriment of all plant and animal life. By applying the technology of today we will ensure man's future on this planet. Mankind has been the only species on this planet that has had the ability to change the physical face of the planet, and mankind is the only inhabitant who can facilitate change and control his destiny.
Currently the Earth's poles are starting to reverse, this is evidenced by the lowering of the magnitude of the magnetic lines of flux around the Earth. The best example of this is in the south Atlantic ocean off the coast of Brazil. This anomaly has been referred to by scientist as, the 'South Atlantic Anomaly'. This 'anomaly' currently encompasses about three million square miles of the south Atlantic Ocean, with a much lower magnetic field allowing excessive amounts of radiation to enter the atmosphere. Southwest of this anomaly is a small area where the lines of flux have actually already reversed, going south instead of north!
Some scientist have misread what is going on in the south Atlantic Ocean, they have looked at the weakening of the Earth's magnetic lines of flux and concluded that we are losing the natural dynamo that produces our protective shield. The study of magnetite in clay pottery (dynamo-stratigraphy) has shown that in the last four hundred years the strength of the Earth's magnetic flux has dropped by about ten percent. Magnetite when heated, as in the firing of clay pots, not only align themselves with the current magnetic north pole (flow of lines of flux), but also absorb the strength of the lines of flux as the magnetite cool.
These scientist have mistakenly concluded the weakening of the lines of flux means the core is cooling quicker than originally thought. Some of these geologist had estimated the Earth's core could cool in as little as fifteen thousand years (not a reasonable estimate), but with the quicker weakening of the flux lines in the last four centuries, these same geologist now believe the core will cool in as little as fifteen hundred years and we will lose the protective sphere surrounding the planet (these scientist could not be more wrong!).
Almost all scientist acknowledge that eventually the Earth will lose the dynamo-motive force at some point in time as the core cools and subsequently we will lose our protective magnetic shield, the same as what happened on Mars about one billion years ago when its core started to solidify.
I repeat, what is happening now with the current weakening of the magnetic field (as evidenced in the south Atlantic and at both poles) is primarily being caused by the polar shift that is now in progress. The earliest the Earth's core will solidify is one and a half billion years from now!
The weakening of the magnetic lines of flux is allowing more ultra violet radiation to penetrate our atmosphere near the equator and the poles. The weakening of the magnetic lines of flux is a natural side effect of a pole reversal. The result of this weakening will be large increases of cancers (the predominate one being skin cancer) and genetic damage for the next two to four generations at the very least.
As the equilibrium of the shift reaches the cross over point (this can take as long as one thousand years or as little as one hundred years), the actual reversal of the magnetic lines of flux will occur in a matter of hours or days at most. The lines of flux around the Earth will see a large drop in magnitude as the polar shift reaches its climax and then will slowly once again strengthen to a point of pre-shift magnitude.
So now we not only have increased radiation at the poles because of the depletion of the ozone layer based on our thirst for fossil fuels, but the natural cycle of the planet's pole reversal gives a twofold hit. As stated, sometimes these polar shifts happen quickly, in a matter of a couple decades, while others last over a period of hundreds of years. As the polar shift concludes, the lines of flux will come out of the North pole and re-enter at the South pole. So instead of your compass pointing North, it will align with the flow of the lines of flux and point South. The magnetic flux will begin to strengthen almost immediately at the end of the cycle and provide ultimate protection for the inhabitants of this world. As stated, the actual time of concern for this population is the crossover point, which will last from a matter of a few hours, to as long as a few days.
The cycle of polar shifts are easily determined by studying the lava flows from volcanoes. The best place to conduct these test are in the Hawaiian Islands, the islands were formed from volcanoes deep beneath the sea and the eruptions continue today, creating a geological laboratory for geologist. By dating the different layers of volcanic rock, geologist can assert a very accurate record of the Earth's magnetic lines of flux as the volcanic rock contains magnetite similar to those found in fired clay pottery.
Over the last twenty million years, there have been about eighteen thousand polar shifts, that is an average of one polar shift every eleven thousand years or so. The last polar shift on this planet was about seven hundred eighty thousand years ago, so it is evident the planet is way overdue for a polar shift. It is true that as a planet ages and the core stabilizes, the polar shifts come less frequently as the dynamo stabilizes its self (such as that of a wobbling spinning top), and the current polar shift may be the last polar shift for millions of years to come, although there is the possibility the poles may shift back to today's present alignment very quickly.
Although this will be the first time mankind on this planet has gone through a polar shift, he will survive. There is no evidence of mass extinctions of the species living at the time of a polar shift, but with the depletion of the ozone layer at man's hands, along with the impending polar shift, it is hard to say just how devastating the shift will actually be to civilization.
Since the planet Earth has been in existence, ninety nine point nine percent (99.9%) of all species that have existed on this planet have gone extinct, either through design or by catastrophic measures.
Two hundred fifty million years ago, during the Permian Era, almost all life on this planet was extinguished. There are a couple of theories that have been debated in recent years as to the cause of this extinction, but as with most things of the past, it is only their best guess as to what actually happened.
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he first theory of the Permian extinction is that there were massive super volcanoes in Siberia that blanketed the Earth in a poisonous cloud of gas and dust. These massive volcanoes were of a magnitude of unimaginable proportion, this particular type of eruption is called a flood basalt eruption. The entirety of what is now Siberia was a sea of molten lava and spurting gasses. The sheer volume of gases put the Earth in a massive state of global warming with as much as a five degree rise in the Earth's overall average temperature over a relatively short period of time. But a five degree rise in temperature alone could not account for the more than ninety five percent of all living plants and animals to perish. In combination with the flood basalt eruptions another event of equal harshness must have occurred simultaneously.
With the rise in the Earth's atmospheric temperature from the flood basalt eruptions, the ocean's temperature also rose to a point that it could no longer hold oxygen. This warming of the oceans and loss of oxygen allowed noxious bacteria to grow uncontrollably and contributed to the ensuing global warming. In addition, this noxious bacteria in the oceans created vast amounts of hydrogen sulfide gas, which in turn quickly depleted the oceans of all but the simplest of life forms (some bacteria and algae). The hydrogen sulfide 'released' from the oceans into the atmosphere and contributed another five or more degrees to the already five degree temperature rise from the flood basalt eruption.
These two events drastically increased the average worldwide temperature to the point that most existing life forms could not adapt to the sudden change created by the massive greenhouse effect. The tremendous increase of temperature and resulting climate change, along with the hydrogen sulfide that flowed out of the oceans and across the land masses, was the end of almost all life of that period in time. All but a very few primitive plants and small creatures did not survive.
The second theory also started with the flood basalt volcanoes, but instead of the second devastating part being hydrogen sulfide as the culprit, some scientist believe it was a massive release of carbon twelve from the oceans. They believe that as the Earth's surface temperature warmed the oceans, the temperature rise caused vast amounts of frozen methane (buried below and on the