Why The Earth Axis Is 23.5°?
As everybody knows, there are four seasons on Earth: spring, summer, fall, and winter. Many people believe that the seasons change because the earth's orbit is elliptical and the distance between the earth and the sun keeps varying. It is not absolutely wrong, but the season changes over time are mostly caused by the rotation axis of the Earth to its orbit. The earth's rotation axis is not vertical to its orbit; it is tilted at 23.5 degrees to its orbit. Knowing the difference of each area’s biome and seasonal differences have been irrelevant to most people in the world, apart from those who travel frequently, across hemispheres. Therefore, this discussion will explore various sources on why the earth’s rotation axis is tilted at 23.5 degrees to its axis.
When the earth has exactly vertical axis to its orbit, all types of biomes will be the same, in the population and genetic make-ups. The seasonal differences on Earth are caused by the income of sunlight, which varies according to earth’s latitude. In addition, the north and the south hemispheres of the Earth show opposite seasons throughout the year. It is because the rotation axis of the planet Earth is tilted at 23.5 degrees to its orbit and it varies the sunlight intensity according to the angle at which it will be received. In this respect, various types of vegetation (biomes) arise: tundra, equatorial, desert and semi desert, temperate and so forth. Based on the biomes, the human population density varies. The human population density is higher in the 30 to 60 degrees latitude compared to that in 60 to 90 degrees and zero to 30 degrees latitude. It is because, the high latitude areas are mostly in tundra and pole climates. Thus, the population density in 30 to 60 degrees is higher because the latitude is convenient for living. However, if the axis of the Earth becomes vertical to its orbit, the income of the sunlight to Earth will be same for all areas and the biomes will be unified into one or two (Smith, 2011).
It is important to note that the 23.5-degree tilt is much important because, when the earth tilts greater, winters will tend to be colder and summers warmer. Moreover, if the tilt becomes smaller, there will be fewer differences in seasons, which may create unusual and harmful swings in the two major seasons of winter and summer. In most cases, it may look as if there are permanent seasons of summer and winter. Therefore, the 23.5-degree tilt allows gradual cyclical preparations for animals and plants to enter into major cycles (McLamb, 2011). The tilting, results in four seasons that enable the conditions and time that plants need to germinate, reproduce and finally die. While some plants may complete their life cycles within weeks, they require certain conditions that vary according to seasons; each season normally has its own conditions for specific plants. Likewise, for biennials, they normally need seasons for storing a lot of energy during the first year, and then use it in the next year to bloom, flower and produce seeds. Perennials require seasons to bloom, flower, produce seeds/ fruits and shed leaves. Therefore, it is important to note that if the specific seasons that espouse certain conditions cannot be guaranteed, plants will simply die because their cycles are genetically pre-programmed.
Moreover, in some animals, the tilt ensures gradual changes towards extreme seasons so that they can migrate from one place to another to survive. Therefore, the animals will have to use the two short seasons to move to places where they can find food, during a drastic season in one part of the planet. Apart from food, they also migrate to other parts of the planet in search of livable conditions such as warm climates for mating. In this regard, when extreme coldness during winter halts the supply of insects or other preys, animals will move to areas with warmer weather where food will be plentiful. Since it is explained that certain plants blossom during warm seasons, when it is warmer in the North Pole, monarchs will emerge to feed on milkweed and their nectar. Therefore, if the earth’s axis become vertically tilted to its orbit, drastic changes in weather conditions will make many animals to die due to abrupt harmful conditions.
Therefore, the 23.5-degree tilting gives the earth the four seasons and climates that are almost perfectly calibrated for a comfortable life. In this respect, apart from ensuring that the temperatures are extreme, between the two major seasons, it has also balanced the distribution of biomes on earth. The four seasons also ensures uninterrupted cycles in both animals and plants, which are vital for their survival.
McLamb, E. (2011). The tilting of the earth: shaping our seasons and climates. Ecology.
Retrieved on 22 April 2014 from http://www.ecology.com/2011/09/10/tilting-earth-shaping-seasons/
Smith, R. (2011).Would our Earth look the same with 0-degree tilt?.BBC. Retrieved on 22 April
2014 from http://www.bbc.co.uk/blogs/legacy/23degrees/2011/03/what_if_the_earth_had_no_tilt.html