About 4.5 billion years ago, our solar system formed from a dense cloud of gas and dust. Our solar system is located in the Milky Way galaxy, which comprises the Sun, the Moon, Stars, Planets, and other celestial bodies. These Celestial bodies include comets, asteroids, and meteors.
The Moon
There are hundreds of known moons and several more to be discovered in our solar system. Our Earth has only one Moon which revolves around it. The surface of our Moon is dusty and barren. It has many craters and steep, high mountains. The atmosphere of the Moon is thin and is called an exosphere. We cannot breathe on the Moon. The Moon is the natural satellite of the Earth. The Moon takes 27.3 days to complete one revolution around the Sun.
Mercury and Venus are the only planets that do not have a Moon. Saturn has 82 moons, and Jupiter has 79 moons.
The Stars
One of the things that you might see in the night sky is a large number of stars. Stars emit light of their own. Interestingly, the Sun is also a star. The stars appear smaller than the Sun because they are millions of times farther away than the Sun. Do you know that Stars can be seen in the sky even during the day? They are not visible because of the bright sunlight. Stars are made up of gases and have heat and light.
You must have seen the stars appear to move from east to west in the sky. It is because of the rotation of the Earth from the west to the east direction.
Constellations
A constellation is a group of stars that form a particular pattern in the sky. They are named after certain objects or animals that are similar to them. One of the constellations that could be visible during summer nights is Ursa Major. It is also known as the Big Dipper, the Great Bear, or the Saptarshi. Ursa Major consists of seven prominent stars. Orion is also another well-known constellation, which can be seen during winter evenings. It has seven or eight stars. It is also called the Hunter. The three stars in the middle represent the belt of the Hunter. Orion is used to locate Sirius, which is the brightest star in the sky. If we draw a straight line passing through the three middle stars and look to the east, we can locate Sirius. Another prominent constellation is Cassiopeia. It is visible in the northern sky during the early nights of winter. Its shape is like a distorted letter W or M.
The Solar System
As we discussed earlier, the solar system has the Sun at the centre, with other celestial bodies revolving around it. One of eight planets that revolve around the Sun is the Earth. The eight planets in order of distance from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto, which was earlier considered a planet, is now considered a dwarf planet. All eight planets revolve around the Sun in a fixed path called an orbit. The first four planets, Mercury, Venus, Earth, and Mars, are inner planets. Since they are made of rocks, they are also called Terrestrial Planets. The planets far from the Sun are Jupiter, Saturn, Uranus, and Neptune, the outer planets.
The Sun
The Sun is the largest object in our solar system. An enormous amount of heat and light is emitted continuously from the Sun that becomes the main source of heat and light for all the planets. The gravity of the Sun holds our solar system together. Earth is 147.5 million kilometres away from the Sun.
Mercury
Mercury is the nearest planet to the Sun and the smallest planet in our solar system. Even though it is the closest planet to the
Sun, Mercury is not the hottest planet in our solar system. Mercury has no moon. Since it is closest to the Sun, it only takes 88 days to revolve around the Sun.
Venus
The nearest neighbour to Earth is Venus. It is the brightest planet in the night sky. Venus appears in the eastern sky before sunrise or appears in the western sky just before sunset. It is therefore called a morning or evening star. There is no moon on Venus. It rotates from east to west, unlike the Earth, which rotates from west to east. It is similar to Earth in terms of its size and density, so it is called the Earth’s twin. It is the hottest planet in our solar system. Venus takes 225 days to revolve around the Sun.
Earth
The only planet in the solar system where life is known to exist is Earth. Our planet is the third planet from the Sun. It is the fifth-largest planet in our solar system. The correct distance from the Sun, the existence of water, and a suitable atmosphere makes it habitable. 70% of its surface is covered with water. There is only one Moon on Earth. It takes 27.3 days to revolve around the Earth.
Mars
Mars is also known as the “Red Planet,” as it appears slightly reddish. It has a cold, desert world with a thin atmosphere, and has two moons. It takes 687 days to revolve around the Sun.
Jupiter
The largest planet in our solar system is Jupiter, which has a faint ring around it. It rotates rapidly around its axis. It has a large number of moons. Jupiter takes 12 years to complete one orbit around the Sun.
Saturn
Saturn is yellowish. It is the second-largest planet in our solar system. The beautiful rings around it make it unique. As mentioned above, it has the most number of moons, i.e., 82. Saturn takes 29 years to orbit the Sun.
Uranus
Uranus is the seventh planet from the Sun, which has 27 moons. It has rings around it, just like Jupiter and Saturn. It takes 84 years to revolve around the Sun. It rotates from east to west like Venus.
Neptune
Neptune is the eighth planet from the Sun, which has rings around it. Neptune has 14 known moons. It takes 165 years to orbit the Sun.
Asteroids
These are small rocky objects that revolve around the Sun. There are a large number of asteroids in our solar system. Most of these asteroids are situated in a region between the orbits of Mars and Jupiter.
Comets
Comets are composed of dust, rocks, and ice. They revolve in an elliptical orbit around the Sun. One of the famous comets is Halley’s Comet, which appears every 76 years.
Meteors and meteorites
A meteor is a small rocky object that enters the Earth’s atmosphere on occasion. They enter at a very high speed. Due to the friction in the atmosphere, they heat up and evaporate quickly.
Meteorites, like meteors, are rocky objects that enter the Earth’s atmosphere and crash to the ground.