THE SOL SYSTEM OR THE SOLAR SYSTEM FOR KIDS
The Solar System is the family of the Sun. It consists of the Sun at the center, the eight planets, their satellites (moons), the asteroids, meteors, comets, and five dwarf planets. The word ‘solar‘ is derived from the Latin word ‘sol‘ meaning the Sun. Thus, we also call it, the sol system. All the members of the solar system move around the sun in different paths, known as orbits. This system is Earth’s local neighborhood in space and the Sun holds everything in it together by an invisible force called gravity.
EXPLORATION OF THE SOL SYSTEM OR THE SOLAR SYSTEM
Long ago, ancient people believed that the Earth was flat and if they traveled to the edges, they would fall. It was common belief during that time, that the Earth was center of everything and all heavenly bodies like the Sun, the Moon, the planets and all stars revolve around it. But later, explorers like Ferdinand Magellan and astronomers like Copernicus proved that the shape of the Earth is spherical. It was the Copernicus who proposed the model of the Universe in which the Sun is at the center of the Universe instead of the Earth. Gradually, we learned the Sun is really just an ordinary star and is only at the center of our local planetary system, the Solar System or the Sol System.
Early astronomers simply used naked eyes to explore the solar system. However, modern astronomers looked through big, powerful telescopes and found other celestial objects like asteroids, meteors, and comets.
HOW OUR SOLAR SYSTEM WAS FORMED?
The formation of our solar system or the sol system took place inside a nebula about 4.6 billion years ago. A nebula is a vast interstellar cloud of dust, hydrogen, and other gases. In this huge area of hydrogen gas, gravity pulls gas and dust together to form clumps. As the size of clump grows its gravity increases and it forces smaller size clumps to revolve around it. As central clump pulls itself tighter it begins to get hot. If its temperature reaches 10 million degrees Celsius, nuclear fusion begins and clumps changes to glowing star or the Sun. Whatever is left, forms planets and other celestial objects which revolve around the Sun. It will be interesting to know that the Sun comprises a total of 99.8% mass of the whole Solar System and the remaining 0.2% forms planets and other objects.
The word ‘planet‘ is derived from the Greek word ‘wanderer‘ as they revolve around the Sun. There are eight planets in our solar system. They move around the Sun in elliptical orbits. In order of their distance from the Sun, they are -Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The first four planets i.e. Mercury, Venus, Earth, and Mars are quite close to Earth and often known as inner planets. The last four planets i.e. Jupiter, Saturn, Uranus, and Neptune are far away from the sun and often known as outer planets. Another reason for their division as inner and outer planets is the presence of an asteroid belt between Mars and Jupiter. As planets comprise of solid material and gases, thus they do not have their own heat and light. They shine with the light reflected from the Sun.
Let us study some special features of the planets. For quick facts on the planets click here.
Mercury is the smallest planet of our solar system and is also the nearest to the Sun. The diameter of Mercury is 4879 kilometers and it is at a distance of approximately 57 million kilometers from the Sun. It has an uneven surface with huge craters and mainly made up of rocks and metals. Being closet to the Sun, therefore it has extreme temperature conditions. The temperature on Mercury varies from 450oC (during the day) to – 170oC (during the night). There is no possibility of life on Mercury. To know more about the Mercury click here.
Venus is the second planet from the Sun. It is the hottest (day temperature of 484oC) and the brightest planet in our solar system. It is hotter than mercury due to the presence of the thick atmosphere of greenhouse gases like – Carbon dioxide. Venus is also known as evening star because of its brightness and easy visibility in the night sky during late evenings. It is almost the same size as that of the Earth. The diameter of Venus is 12,104 kilometers and it is at a distance of approximately 108 million kilometers from the Sun. To know more about the Venus click here.
Earth is the third planet from the Sun. It is the only planet in our solar system that has life on it. The diameter of Earth is 12,742 kilometers and it is at a distance of approximately 149 million kilometers from the Sun. This distance is such that it receives a sufficient amount of heat and light from the Sun. The atmosphere of the Earth contains oxygen which is necessary for life to exists. The atmosphere of the earth helps in maintaining a moderated temperature range during day and night. The earth also has water on it. All these factors make life possible here. To know more about the Earth click here.
Mars is the fourth planet from the Sun and the second nearest planet to the Earth. The diameter of Mars is 6,779 kilometers and it is at a distance of approximately 228 million kilometers from the Sun. It is often called the red planet due to the red appearance of its surface. The average temperature on Mars varies from -63oC to 20oC. There are so far no traces of life on Mars. However, it is the only planet to have an atmosphere and daytime temperature remotely like the Earth’s. Some evidence suggested that microscopic life once lived at or below the surface of Mars and there may still be water underground. To know more about the Mars click here.
The Jupiter is the fifth planet with a distance of approximately 778 million kilometers from the Sun. It is the largest planet of our solar system. It is about 1400 larger than the Earth. Its diameter is 139,882 kilometers. It is at a great distance from the Sun. Thus, its temperature always remains in the negative range, i.e. – 124oC to -13oC. Jupiter like all other outer planets is mostly made up of hydrogen and helium gas. To know more about the Jupiter click here.
The Saturn is the sixth planet of the solar system. The diameter of Saturn is 116,774 kilometers and it is at a distance of approximately 1,426 million kilometers from the Sun. It is almost as big as Jupiter and also made largely of liquid and solid hydrogen and helium. It is surrounded by a shimmering halo of rings which consist of billions of tiny blocks of ice and dust, most no bigger than a tennis ball. To know more about the Saturn click here.
The Uranus is the seventh planet from the Sun. The diameter of Uranus is 50,724 kilometers and it is at a distance of approximately 2,870 million kilometers from the Sun. It is a gaseous planet with almost featureless appearance. The Uranus also has few rings around it but not as prominent as that of Saturn’s. It is so far from the Sun that temperature on the surface plunges to minus -201oC.To know more about the Uranus click here.
The Neptune is the farthest planet of our solar system with an approximate distance of 4,498 million kilometers from the Sun. The diameter of Neptune is 49,244 kilometers slightly less than the Uranus. It has a blue color and is a typical gas planet. Its main feature is its Great Dark Spot in its southern hemisphere. It mainly consists of ice rocks of hydrogen and helium. It is the fourth largest planet in our solar system. To know more about the Neptune click here.
Satellites are small bodies that revolve around the planets. They are of two types; natural and artificial. The moon is a satellite of the Earth and it is a natural satellite. An artificial satellite is a man-made object that orbits the earth or other planets. Like planets, satellites also do not have any heat or light of their own. They shine by reflecting the light from the Sun. The Earth is not the only planets which have natural satellite or the Moon. Mars has two, Jupiter has 63, Saturn has 34, Uranus has 27 and Neptune has 13 natural satellites. Ganymede is the largest natural satellite of Jupiter while Titan is the largest satellite of Saturn. To know more about satellites click here.
The Moon is the Earth’s only natural satellite. It is about 3,85,000 kilometers away from the Earth. Its diameter is about one-fourth of the Earth. The Moon is cold and dry, with a rocky surface. There is no air and water on the Moon. In the absence of atmosphere, the Moon has no protection against the strong rays of the Sun. This leads to extreme changes in temperature during the day (123oC ) and night(- 233oC). All these features make it impossible for life to exists on the Moon. The Moon gravity is one-sixth of the Earth. So, you would be able to lift even heavy objects very easily on the moon. If you can jump one meter on the Earth, you will be able to jump six meters on the Moon. To know more about the Moon click here.
Along with the planets and their moons, thousands of smaller bits of rock and ice circle around the Sun. They range from tiny particles to mini planets hundreds of miles across. These are asteroids or planetoids. They are leftover debris of the solar system – fragments too scattered to gather together to form a proper planet. They revolve around the sun in their own orbits. Most of these rocks lie in a wide band between the orbits of Mars and Jupiter, called the asteroid belt. There are about 40,000 such asteroids, the largest of which is Ceres. To know more about asteroids click here.
METEOROIDS, METEORS, AND METEORITES
Meteoroids are those rocks which somehow spin out of asteroid belt and starts revolving around the Sun in different orbits. Some of these meteoroids enter the Earth’s atmosphere with great speed and due to friction, get heated up and start glowing. We call these glowing and moving objects, meteors or shooting stars. Fortunately, most meteors are so small they burn as they hit the atmosphere and never reach the Earth surface. But, some are quite large and survive the fall and land on the Earth surface. They are then called meteorites. To know more about meteoroids click here.
Comets are celestial bodies made of snow, dust particles, and frozen gases. They revolve around the Sun in elongated orbits. Due to their elongated orbit, they come near to the Sun after a very long period. Normally, comets have an appearance of a dirty snowball but when they approach the Sun, the gases get heated up and start glowing. Dust, vapors, and gases are blown out in a form of huge tail millions of mile long. Because the tail is blown by the Sun, it always faces away from the Sun. As the comet passes the Sun and heads out into deep space again, it tail faces the direction it is moving. To know more about comets click here.
EDGE OF THE SOLAR SYSTEM OR THE SOL SYSTEM
Edge of the Solar System is not Neptune’s orbit. However, it extends beyond in form of dwarf planets, Kuiper belt, and Oort cloud. Apart from eight major planets, there are 5 dwarf planets – Pluto, Ceres, Haumea, Makemake, and Eris. Kuiper belt is the region of asteroids similar to a region between the Mars and the Jupiter and the Oort cloud is the spherical region covering the entire Solar system. It contains numerous comets. The size of the Solar System is measured in AU (Astronomical Unit). 1 AU is equal to the distance of the Earth from the Sun. So, our Solar System is about 100,000 AU in diameter.