The Solar System Chapter Notes | Science for Class 3 PDF Download

What is Solar System?

The solar system is a bunch of planets, moons, asteroids, and comets that are all held together by the gravity of our Sun. So basically, it's like a big family of Objects floating around in space, with the Sun in the middle keeping everything together.

• These objects include planets, asteroids (pieces of rocks), natural satellites, meteoroids, comets, dwarf planets, dust and gases. 
• Our solar system is a part of the Milky Way Galaxy. There are many such galaxies in the universe.

Sun

• The sun lies in the center of the Solar system. It is massive ball of burning gas called a star. 
• It is around 100 times bigger than our earth. Sun looks bigger because it closer to the earth than the any other stars. 
• Sun is very hot because of continuous huge explosion of gases happening in the sun. 
• It gives heat and light to planets in the system. Light from the sun reaches earth in approximately 8 minutes. The sun looks yellow from earth. 
• Without the sun, life is not possible on earth. Sun’s light is very strong so, we should avoid looking at the sun directly as it could damage our eyes. 
• Sun is very important for our existence on earth. In the absence of sun our earth would be just a ball of ice coated rock.

Significance of sun in our life

• It gives light
• It provides energy to the plant to prepare food.
  
• It is an important part of water cycle.
  
• It gives us vitamin D.
  
• It kills germs and dries our clothes.
  
• It is the ultimate source of energy.
  
• It warms the atmosphere.

Mercury

The closest planet to the sun is Mercury. It has rocky surface with large holes called craters. These craters were made by fast moving rocks hitting into the planets from the space. 

• When we look at mercury from earth, these craters looks like dark spot. Mercury has no atmosphere. 
• Life is not possible on mercury because it is either too hot or too cold. Mercury has no moon.

Venus

Venus is the second planet from the sun. It is almost as big as earth. It has thicker atmosphere compared to earth.

• The sun ray’s passes through the thick clouds and warms the planet’s surface but the cloud stop the heat from escaping which makes the planet very hot. 
• Venus is the hottest planet in the solar system and so life is not possible there. Venus also rotates in the opposite direction as almost all the other planets. 
• Instead of the Sun rising in the east and setting in the west, the Sun on Venus would appear to rise in the west and set in the east. Venus has no moons.

Earth

The earth is at the right distance from the sun and has right mixture of air, heat and water which makes life possible on earth.

• It is the only planet where life is known to exist. Earth is 7926 miles in size. About 70% of the earth is covered with water and 30% with land. Earth has one moon.
• Moon is natural satellite. Scientists have sent many man made satellite which revolve around the earth. 
• These satellites help to capture important information about earth such as weather forecast etc. and helps in transmission of radio and television programs. 
• Existence of life on earth makes it unique planet in the solar system.

Mars

• Mars is cold and fourth planet from the sun. It has two moons.
• It is a rocky planet. 
• Its surface is covered with red dust and hence called red planet.

Jupiter

Jupiter is the biggest planet in the solar system. It is the fifth planet from the sun. It is made mostly of gases and does not have solid surface.

• There is huge storm that has been raging for thousands of years and hence it is referred as stormy planet. 
• Different cloud formation and storms in the atmosphere make Jupiter a colorful planet. It has a big red spot where storm raging for at least 300 years. 
• This red spot is also called “The Eye of Jupiter”. Jupiter is also a cold planet. It has more than 60 moons moving around it.

Saturn

Saturn is the second largest planet in the solar system. It is sixth planet from the sun. It is made mostly of gases.

• It has millions of pieces of rock and ice moving around it. These look like solid rings. Jupiter, Uranus and Neptune also have rings. 
• From far away, these look like solid rings. It has 62 moons.

Uranus

Uranus is the seventh planet from the sun. Uranus is a gas giant. Uranus spins differently. It spins on its side.

•  It is an extremely cold planet and hence been called the “ice giant”. It has faint rings around it which made of millions of specks of dust. It has 27 moons.

Neptune

• Neptune is the eighth planet from the sun. 
• It is very cold planet like Uranus. 
• There is dark blue swirl of storm raging on the planet which makes it look blue in color. 
• It has 14 moons.

Dwarf Planet

Pluto used to be considered the ninth planet in our solar system, but now scientists call it a "dwarf planet."

• It's smaller than the other planets, and it's really far away from the Sun. It's way out past Neptune. 
• Some people still think of Pluto as the ninth planet because it was considered one for a long time, but scientists changed their minds about it.