The planet Earth is exposed to various external risks; perhaps the most important of them at the present time are magnetic storms that originate from the sun and meteorites of multiple sizes that collide with the Earth over time. This paper discusses these two phenomena and assesses their impact on the planet Earth.
Keywords: Solar System, Meteorites, Magnetic Storms, Earth Risks, Asteroid Belt.
The solar system contains eight planets with their moons and many objects that deserve attention such as comets, meteors and asteroids, where the sun constitutes approximately 99.85% of the mass of the group while the other planets represent the rest percentage as shown in figure 1. Due to the force of solar gravity, each planet retains an almost circular orbit and revolves around the sun in a counterclockwise direction and about different axis orientations.
Figure 1: The solar system .
2. The Solar Activity
The sun is the first source that threatens human life on the surface of the earth due to its great impact on economic, health activities, and human behavior. Such impacts come from sunspots activity. The importance of studying this topic lies in the consideration that many scientists believe that sunspots activity have a direct relationship to human life on Earth. There are many theories, interpretations, and statistics through which scientists try to find connections between sunspots activity, health activity, economic, agricultural, and human behavior. On the other hand, some scientists also believe that global warming is due to reasons of human activities, although the real causes of this phenomenon are not yet known. Preliminary studies on this phenomenon have shown that global climate change is not only a ground phenomenon but also due to solar system activity. The generation mechanisms of the sunspots are explained elsewhere .
In a recent case, Earth-orbiting satellites detected the strongest magnetic storm resulting from a solar flare and Coronal Mass Ejection (CME) event. Figure 2 illustrates the size of the CME shockwave edge with respect to the size of the sun at the point of the outburst. The eruption that produced this flare also sent a solar rippling through the sun’s atmosphere and ejected a CME toward Earth. By the time the CME reached the Earth, the shockwave leading edge had expanded to approximately 40 million miles across .
Figure 2: Solar flare and coronal mass ejection at the time of the eruption .
Additionally, eruptive and transient phenomena in the sun/corona and in the interplanetary medium can lead to the acceleration of energetic particles with greatly enhanced flux. Such processes can modify the radiation environment on Earth and need to be taken into account for planning and maintaining space missions. Solar activity can cause, through coupling of solar wind and the Earth’s magnetosphere, strong geomagnetic storms in the magnetosphere and ionosphere, which may disturb radio-wave propagation and navigation-system stability, or induce dangerous spurious currents in long pipes or power lines. Another important aspect is the link between solar-activity variations and the Earth’s climate . These changes have a great impact on the terrestrial environment and on many aspects of human lives. Therefore, studying and modeling solar activity can increase the level in demand to understanding of nature.
It is important to study solar variability on different timescales. The behavior of solar activity in the past (see figure3.) is of great importance for a variety of reasons:
Figure 3: Sunspot observations on different timescales 
(i) It allows an improved knowledge of the statistical behavior of the solar-dynamo process, which generates the cyclically varying solar-magnetic field. (ii) Making it possible to estimate the fractions of time the sun spends in states of very-low activity called grand minima. Such studies require a long time series of solar activity data. The longest direct series of solar activity is the 400-year-long sunspot-number series, which depicts the dramatic contrast between the (almost spotless) Maunder minimum and the modern period of very high activity. This allows one to study the temporal evolution of solar magnetic activity, and thus of the solar dynamo, on much longer timescales than are available from direct measurements . Although sunspots have been extensively studied for almost 400 years and their magnetic nature has been known since 1908, gaining the knowledge about their basic properties is still evolving .
During the Maunder Minimum periods of low solar sunspot activity, there was also an increase in the ratio of radio-carbon 14 (14C to 12C) in tree rings and there were documented changes in the aurora borealis. Each of these periods was known for bitterly cold and prolonged winters in the Northern Hemisphere. The Maunder Minimum occurred during most of the 17th Century and the first decade of the 18th Century . A later period of relatively low sunspot activity commenced in the last two decades of the 18th Century and lasted for the first three decades of the 19th Century. This period is known as the Dalton Minimum. The two grand minima were collectively called the (Little Ice-Age) .
Many studies have suggested the sunspot activity influences on Nature’s Risks, and explain how the decreased levels of sunspot activity will affect long-term weather risks as well as long-term earthquake and volcanic risks . The aim of these studies is to encourage the actuarial profession to develop skills in space weather forecasting and understand the risk management activities that arise from such abilities. Also to understand why, at certain times, when solar flares that hit Earth, they have the ability to temporarily significantly change climatic conditions, earthquake and volcanic risks. Understanding just these mechanisms should convince the profession to develop important real-time risk management tools and capabilities that can be applied in many areas of expertise as well as in new areas where actuaries where actuaries are unaware of. Understanding how natural forces (in particular the current prolonged low sunspot activity of the sun) affect a number of risks that should interest actuaries. These include human mortality, natural events such as major earthquakes and volcanic eruptions, direct weather related risks, in particular, from weather extremes .
Other category of risks that are important, include risks relating to food and energy security, the political risks arising from unaffordable increases in the price of these commodities, crop insurance and other forms of insurance that are affected by climatic extremes. Understanding the sun-climate connection requires a breadth of expertise in fields such as solar activity, plasma physics, energetic particle physics, atmospheric chemistry, fluid dynamics, and even terrestrial history. However, researchers are asked to have the full range of knowledge required to solve the sun-climate connection problem.
3. Asteroid Belt
The second threat to life on Earth's surface is the existence of the Asteroid Belt in the solar system. Asteroid Belt is different sized bodies believed to have been remained since the formation of the solar system 4.6 billion years ago. They are rocky bodies of irregular shapes, and most of them are small in size. The asteroid belt lies in an area between Mars and Jupiter and is called the main belt (see figure 4.).
Figure 4: The Asteroid Belt .
Planet Ceres is one of the largest bodies in this belt, as it represents about 25% of the mass of the belt, followed by asteroids Pallas, Hygiea, and Vesta, represent about half the mass of this belt. Asteroids Belt ranges in size from Ceres as its largest body to grains like dust particles. Most asteroids are irregularly shaped, but some are nearly spherical and often contain craters. The asteroids orbit in elliptical orbits around the sun, and they also revolve around themselves, in irregular rotations .
3.1 Source of Meteorites
While the asteroid belt is considered the most probable source of meteorite origin, some meteorites have chemical structures similar to samples collected from the surface of the moon, (where Allan Hills 81005 is the first meteorite from the origin of the moon) and others believe that it came from Mars due to collisions of other asteroids or from The path of volcanic eruptions on its surface. Records from the past time have shown that large meteorites cause tremendous damage to the planet Earth and to life on it. A collision of a large meteorite with the earth may lead to the generation of a crater with a diameter of 10-20 km, at about twice its diameter. Such meteorite impacts with the planet Earth lead to the generation of a force equivalent to the force of an explosion between one nuclear bomb to thousands of nuclear bombs (see figure 5).
Figure 5: The frequency of meteorites colliding with Earth
and its relationship to meteorite size 
The force generated by the collision varies according to the size and speed of the meteorite, for example: the force of the Siberian meteorite explosion in 1908 was 1,000 times stronger than the Hiroshima bomb. Figure 6, shows some of the meteorite collision sites with the Earth .
Figure 6: The density of meteorites fall on continents .
Figure 7, shows the Vredefort crater, with an estimated diameter of 300 kilometers, is the world's largest known impact structure. It was created when an asteroid measuring at least 10 kilometers landed on Earth an estimated 2 billion years ago.
Figure 7: The Vredefort crater 
However, solutions to prevent meteorites colliding with the Earth are suggested: (i) Destruction of a meteorite from one side outside the Earth's airspace by using nuclear missiles, which could deflect the meteor's path away from the Earth. (ii) The attempt to propel the jet, which is based on sending a vehicle to the meteorite to join with it and try to change its path. (iii) The meteorite was pushed by gravity by sending a very huge vehicle that moves in parallel with the meteor, and as a result of its speed, gravity produces a slight movement of the meteor, causing it to derail its path.
The subject of meteorites at the global level is of great scientific and environmental importance, and this importance lies in the field of space physics, through which the components of meteorites are studied, which reflect the components of the solar system when it was formed. The other importance is an environmental importance that is directly related to the future of human civilization due to the violent destructive phenomena they cause on Earth and this requires studying the mechanics of meteorites colliding with Earth and estimate the extent of the devastation they are causing on the surface of the earth [13-18].
Understanding the solar system cycle remains the main problem in solar physics. Although sunspots activity has been extensively studied for almost 400 years and their magnetic nature has been known since 1908, our knowledge about their basic properties is still evolving. Climate change on the planet is presently one of the most controversial debates among experts and scientists. Some scientists believe that global warming is due to reasons of human actions, although the real causes of this phenomenon are not yet known. However, lead-in studies on this phenomenon have shown that global climate change is also connected to sunspots activity.
The subject of space physics is one of the most important topics in the field of scientific research, which enjoys global attention and gives distinctive value to the leading universities in research capabilities and the number of scientific publications related to this field. Among the important topics in the field of space physics is the subject of meteorites. Meteorites are remnants resulting from the formation of the solar system, the study of meteorites, allows identifying the chemical compositions of the solar system when it was formed as well as estimating the extent of the devastation they are causing on the surface of the earth and to find Possible solutions to prevent their collision with the Earth.
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