Jasmine Grover Content Strategy Manager
Content Strategy Manager
Solar system consists of the sun along with stars, satellites, and other planets that revolve around the sun in their orbit. The stars of the Milky way galaxy orbit around the sun along with over 210 planetary satellites and a number of asteroids. Other icy bodies and comets which are formed of dust particles and highly tenuous gases are also an important part of our solar system. Earlier, our solar system had 9 planets when in 1930 Pluto was announced as a planet. However, the astronauts later in 1992, announced that Pluto is in fact an icy body, not a planet that is located far away from our sun. Therefore, the number of planets in our solar system came down to 8. In this article, we will learn more about the solar system, moons, asteroids, planets, comets, and understand their movement in the solar system.
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Key Takeaways: Solar System, Planets, Sun, Asteroids, Comets, Meteors, Dwarf Planets, Satellites
What is the Solar System?
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Solar system is a huge system of about 15 trillion km in size i.e. about 100 astronomical units (AU). It is held together by the immense gravitational pull of the sun which is responsible for maintaining the orbit of the planets and asteroids around it. The icy bodies that are present in the solar system are referred to as interplanetary mediums. Sun is the largest object of our solar system which is responsible for providing energy to the Earth through the nuclear reactions that take place at its core. It makes up about 99% of the mass of the entire solar system. It is formed of hydrogen gas and also has a small amount of helium gas present. The Sun is also a star that has a surface temperature of about 6000° C.
Solar System
Read More: Motion of Celestial Bodies in Space
Orbits
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All the planets and dwarf planets present in the solar system along with the icy bodies present in the Kuiper Belt revolve around the sun in an elliptical orbit. The shape of the orbit is determined by the eccentricity. For example, an exact circular orbit has an eccentricity of zero while an elongated orbit will have its eccentricity somewhere near 1.
- The Orbits of planets such as Neptune and Venus are almost circular around the sun.
Therefore, their eccentricities are 0.009 and 0.007 respectively.
- Despite being the closest planet to the sun, Mercury has a high eccentricity of about 0.21.
- The dwarf planet Pluto has an eccentricity value of 0.25.
Orbits
Inclination
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Inclination is also an important property for an object orbiting around the sun. Each object is inclined in a particular way. For instance, the orbit of Earth is in an ecliptic plane.
- The smallest planet in the solar system, i.e. Mercury has the greatest inclination with a value of about 7°.
- The icy body, Pluto, has a steep inclination of 172°.
Some of the comets present in the Oort Cloud have a greater inclination, even more than 90°. Therefore, they look like they are rotating in an opposite direction.
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Composition of solar system
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Our solar system is composed of the sun which is surrounded by 8 large objects that are nearly spherical in shape, also known as planets. They move around the sun in elliptical paths which are referred to as the orbits. Our Earth is also one such planet that lies at an appropriate distance from the sun to make the existence of life possible such that it is neither too hot nor too cold. The solar system also has small irregularly shaped objects that are formed of carbon, metal, and rock, known as asteroids. Most of the Asteroids lie in the region of the asteroid belt between the orbits of Mars and Jupiter.
Composition of solar system
Our solar system is made up of the Sun and all the things that are bound to it through gravity. It consists of:
- Sun
- Planets such as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune
- Asteroids
- Dozens of moons
- Comets
- Meteoroids
- Dwarf Planets like Pluto
Read Also: Value of g on Moon
Sun
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Our sun is a star that is about 4.5 billion years old. It is a hot ball that is made up of hydrogen and helium and is present at the center of the solar system. Sun is at a distance of about 93 million miles from Earth. Without the energy and light from Earth, life would not exist on our planet. It is the largest object in our solar system. The volume of the sun is about 1.3 million times the volume of the Earth. The gravity of the sun holds together our solar system. The activity at the core of the sun influences the solar system and the nature of space.
Sun
Also read: Which is the nearest planet to the sun?
Planets
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About 4.6 billion years ago, when the discs of gas and dust orbiting around the sun collapsed, they clumped together due to the presence of gravity and eventually formed planets. Planets in our solar system are mainly of two types:
- Rocky planets are mostly composed of metal and solid rock. They include Mercury, Venus, Earth, and Mars. These are the only planets in our solar system that have oxidized compounds like carbon dioxide. Amongst them all, Earth is the only planet that possesses a strong magnetic field.
This field helps Earth to protect itself from interplanetary mediums. The magnetic field of Earth also works by attracting some electrically charged particles present in the interplanetary medium towards its own self. This is also known as the magnetosphere.
- Gas giants are mostly formed of gases such as Hydrogen, methane, helium, etc. Gas giants are bigger in comparison to rocky planets. These include Jupiter, Saturn, Uranus, and Neptune. These planets don't have a solid surface and have low densities.
Planets
Asteroids
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Asteroids are the big chunks of metal and rock that move in an orbit around the sun between the paths of Mars and Jupiter where the asteroid belt lies. These lumps of rocks are smaller than planets and therefore are also known as minor planets. They are not visible to us by the naked eye. However, they can be observed through small telescopes or binoculars.
Asteroids
Satellites
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The objects that are a part of the solar system which revolve around the planets are known as satellites. Moon is the natural satellite of our Earth. Some satellites such as Ganymede which orbits around Jupiter can have an atmosphere and are even bigger than Mercury.
Moons of the planets have various sizes, shapes, and types. Few moons even have atmospheres or oceans hidden beneath the surface of the moon. Most of these moons have probably been formed from the discs of dust and gas that were circulating around the planets in our solar system. Some of the moons are also captured objects that were formed somewhere else and then fell into orbit around the larger planets.
Satellites
Our solar system also has artificial satellites. These are man-made satellites that revolve around the Earth, even closer than the moon. The first artificial satellite of India was known as Aryabhata. Other Indian satellites launched in space include IRS, INSAT, and EDUSAT.
Read More: Life Cycle of Stars
Comets
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Small objects with an irregular shape that are made up of ice are known as comets. Usually, comets originate from the outermost solar system, a region beyond Neptune which is known as the Kuiper Belt. When these icy objects reach closer to the sun, the ice in them vaporizes and forms a beautiful tail behind the comets which is known as the coma. Some of the comets appear regularly in our solar system at regular intervals. One of the most famous comets, Halley's Comet appears once every 76 years.
Comets
Read More: Advanced Sunrise and Delayed Sunset
Meteoroids
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Meteoroids refer to the objects present in space that vary in size from small grains to small asteroids. They can also be understood as rocks of space. When these meteoroids enter the atmosphere of the Earth or of another planet, they burn up. These high-speed fireballs are also known as shooting stars. They are called meteors. When a meteoroid manages to survive a trip through the atmosphere of the planet and ultimately hits the ground, it is known as a meteorite.
Meteoroids
Dwarf planets
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There are some objects in our solar system that are smaller than the planets but larger than the asteroids. They move in an orbit around the sun at many places. They are known as dwarf planets and the nearest dwarf planet to our Earth is known as Ceres and it lies in the asteroid belt. The most popular dwarf planet is Pluto which was earlier regarded as a planet. It lies in the inner region of the Kuiper Belt beyond Neptune. Pluto and its 5 satellites were visited by a spacecraft in 2014. The spacecraft named New Horizons captured images of this icy dwarf planet for the first time in history and in high resolution.
Dwarf Planets
Things to Remember
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- Our solar system is composed of a star known as the sun, 8 planets, and various other small bodies such as asteroids, comets, and dwarf planets.
- The solar system orbits at 515,000 miles per hour around the center of the Milky Way Galaxy.
- Our solar system is in a spiral arm of the Milky Way Galaxy.
- Our solar system has no atmosphere. However, it has many worlds such as Earth which has an atmosphere.
- The planets in our solar system along with some asteroids have about 200 moons around them in their orbits.
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Sample Questions
Ques. What is a Kuiper Belt? (5 marks)
Ans. Kuiper Belt is a donut-shaped region that is composed of icy bodies that are located beyond the orbit of the planet Neptune. About millions of icy objects in this distant region of the solar system are collectively referred to as trans-Neptunian objects (TNOs) or Kuiper Belt Objects, known as KBOs.
The Kuiper Belt is like the asteroid belt which is a region where the leftover items of the solar system have been present since earlier times. Short-period comets that usually take less than two hundred years to complete their motion around the Sun are known to originate from the Kuiper Belt. There are many dwarf planets present in the Kuiper Belt that also have their moons around them.
Ques. What are comets? (3 marks)
Ans. Comets are the icy or frozen leftovers from the time of formation of our solar system. They are formed of rock, ice, and dust. Comets vary in size from a few miles to about tens of miles. As these comets approach the sun, they get heated up and eventually spew out dust and gases forming a tail, also known as a coma. Their tails or glowing heads can even be larger than planets. There are billions of comets present in the distant Oort Cloud and the Kuiper Belt.
Ques. Explain what a solar system is. (3 marks)
Ans. The solar system is formed of eight planets, moons, and various other heavenly bodies. Our solar system is a part of the galaxy known as the Milky Way Galaxy. At the center of our solar system is a star known as the sun. All the planets and other celestial bodies revolve around the sun in an elliptical orbit. Earth is the only planet in our solar system that is capable of sustaining life. Energy is supplied to Earth through the sun.
Ques. What are the favorable conditions that facilitate life on Earth? (5 marks)
Ans. The ideal conditions for sustaining life on Earth are as given below:
- Earth is present at an ideal distance from the sun. Hence, the atmosphere of the Earth is neither too hot nor too cold. This ideal temperature on Earth makes possible the presence of life.
- Earth is enveloped by a blanket of air that is made up of life-supporting gases such as nitrogen, oxygen, carbon dioxide, etc.
- The ozone layer that is present in the atmosphere is responsible for protecting living things from the ultraviolet and harmful radiations of the sun.
- The presence of an adequate amount of water in rivers, lakes, seas, oceans, etc also is ideal for the evolution of life on Earth.
- Suitable weather conditions and seasons also play an important role in supporting the existence of life on Earth.
Ques. How many planets are there in our solar system in order? (5 marks)
Ans. There are 8 planets in our solar system which are as follows:
- Mercury: It is the smallest planet in our solar system and is also the one that is located closest to the sun. In size, it is just a bit larger than the moon of the Earth. It is the fastest planet that completes its revolution around the sun in 88 days.
- Venus: Venus spins with a slower speed opposite to the direction of most of the planets. It has a thick atmosphere that is responsible for trapping heat that creates a greenhouse effect. This makes Venus the hottest planet in our solar system.
- Earth: Our home planet Earth is the only known planet till now which is inhabited by living beings. It is the only planet that has liquid water present on its surface.
- Mars: Mars is a cold and dusty planet in our solar system that has a thin atmosphere. Strong evidence suggests that about billions of years ago, mass was warmer and better and had a thicker atmosphere.
- Jupiter: Jupiter is almost double in mass than all the other planets of our solar system combined.
- Saturn: Adorned with a complex and dazzling system of icy or frozen rings, Saturn is one of a kind planet in our solar system. Even though the rest of the gas giants do have rings, none of them are as spectacular as the rings of Saturn.
- Uranus: The seventh planet from the sun is Uranus which rotates at about 90° angle from its orbital plane. Due to this reason, Uranus seems to spin on its side.
- Neptune: The most distant and the last planet of our solar system that orbits the sun is cold and dark. It has supersonic winds and was identified through mathematical calculations.
Ques. What are moons? What are the various types of the moon in our solar system? (3 marks)
Ans. Moons are also referred to as the natural satellites of the planets and asteroids that orbit them. Earth has one moon while our solar system is composed of more than 200 moons. All the major planets with the exception of Venus and Mercury have moons. Some dwarf planets such as Pluto and many asteroids also possess small moons. The maximum amount of moons is possessed by the giant planets Jupiter and Saturn.
Moons have various sizes, types, and shapes. Few moons also have atmospheres and even oceans that are hidden beneath their outer surfaces. Most of the moons of the planets are formed from the discs of dust and gas that circulated around the planets in the solar system in earlier times while other moons are just some "captured objects" that were formed somewhere else and then they fell into the orbits of planets.
The various types of moons in our solar system are:
- Earth's Moon: Earth has only one natural satellite that acts as a stabilizing force which makes life more pleasant on Earth.
- Mars' Moon: This red planet has two moons. One of them named Phobos is gradually being torn apart from the forces of Mars.
- Jupiter Moons: Moons such as icy Europa that have a hidden ocean move around this giant planet.
- Saturn Moons: Some of the moons of Saturn shaped its spectacular rings. One of them is even equal to a planet in size.
- Uranus Moons: These distant ice giants are known as the literary moons as they are named after the characters of Shakespeare's plays
- Neptune Moons: A moon of Neptune known as Icy Triton can be a captured object that was earlier present in the Kuiper Belt.
- Pluto Moons: One of the moons of pluto called Charon is so big in size that it even makes this dwarf planet wobble.
Ques. What is a meteor shower? Give some examples of prominent meteor showers. (5 marks)
Ans. A lot of materials from the meteors fall into the atmosphere of Earth every day. Almost all of this material gets vaporized and leaves behind a bright tail that is popularly known as a "shooting star". On any given night, one can observe several meteors per hour. Sometimes, the number of these meteors increases, and hence meteor showers are observed.
Meteor showers can be experienced annually or even at regular intervals when our Earth passes through the trail of the debris and the dust that is left behind by a comet. Usually, meteor showers get their name from the constellation or the star that appears close to these meteors in the sky.
One of the popular examples of meteor showers is the Perseid meteor which peaks every year in the month of August. Each Perseid meteor is a small piece of the Swift Tuttle comet that swings by the sun in about 135 years or so.
Some of the notable meteor showers are:
- Quadrantids in the month of January. These are considered as one of the best annual meteor showers.
- Lyrids in April is one of the ancient meteor showers that have been observed for about 2700 years.
- Eta Aquarids in May is known for their exceptional speed.
- Delta Aquarids in July become active around mid-July and last till late August. These are faint in appearance and therefore can't be identified easily.
- Perseids in August are regarded as the best meteor showers that occur all around the year.
- Orionids in October is considered the most beautiful meteor showers.
- Leonids in November are a major meteor shower though the rates at which meteor moves is low i.e. just about 15 meteors pass per hour.
- Geminids in December is a reliable meteor shower that peaks around mid-December.
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