🌞 OUR SOLAR SYSTEM
1. What is the Solar System?
The Solar System is a group of the Sun, eight planets, their satellites, and other celestial bodies.
The Sun is at the centre of our Solar System. The planets and other bodies move around the Sun because of the Sun's gravitational force.
Members of the Solar System
The Sun
Eight planets
Natural satellites
Asteroids
Comets
Meteors and meteorites
Other small celestial bodies
☀️ 2. The Sun
The Sun is a star and is the main source of light and heat for our Solar System.
Important points about the Sun:
The Sun is a star.
It is made mainly of hydrogen and helium gases.
It produces its own light and heat.
It is the largest object in our Solar System.
The Sun's gravitational force keeps the planets in their orbits.
Life on Earth depends greatly on the energy received from the Sun.
Remember: The Sun is a star, not a planet.
🪐 3. What is a Planet?
A planet is a celestial body that moves around a star in a definite path called an orbit.
A planet does not produce its own light. It reflects the light of a star.
There are eight planets in our Solar System.
Order of planets from the Sun:
Mercury → Venus → Earth → Mars → Jupiter → Saturn → Uranus → Neptune
Easy way to remember:
M V E M J S U N
🪐 4. The Eight Planets
① Mercury
Mercury is the nearest planet to the Sun.
It is the smallest planet in our Solar System.
It has no natural satellite.
It has a very thin atmosphere.
It takes the least time to complete one revolution around the Sun.
Its surface has many craters.
Remember:
Nearest to the Sun = Mercury
Smallest planet = Mercury
② Venus
Venus is the second planet from the Sun.
It is nearly the same size as Earth.
It is called the sister planet of Earth.
It is the hottest planet in the Solar System.
It has no natural satellite.
It has a thick atmosphere, mainly containing carbon dioxide.
Venus is very bright and can be seen from Earth.
Remember:
Hottest planet = Venus
Sister planet of Earth = Venus
③ Earth
Earth is the third planet from the Sun.
It is our home planet.
Earth is the only planet currently known to support life.
It has air, water and a suitable temperature for life.
Earth has one natural satellite—the Moon.
Earth is called the Blue Planet because a large part of its surface is covered by water.
Remember:
Our home planet = Earth
Blue Planet = Earth
④ Mars
Mars is the fourth planet from the Sun.
It is called the Red Planet.
Its reddish colour is mainly due to iron minerals in its soil.
Mars has two natural satellites: Phobos and Deimos.
It has mountains, valleys and large volcanoes.
Scientists study Mars to learn more about the possibility of life beyond Earth.
Remember:
Red Planet = Mars
⑤ Jupiter
Jupiter is the fifth planet from the Sun.
It is the largest planet in our Solar System.
It is a giant planet made mostly of gases.
Jupiter has many moons.
It has a huge storm called the Great Red Spot.
It rotates very quickly compared with many other planets.
Remember:
Largest planet = Jupiter
⑥ Saturn
Saturn is the sixth planet from the Sun.
It is famous for its beautiful rings.
Saturn is a giant planet made mostly of gases.
Its rings are made mainly of ice, rock and dust particles.
Saturn has many moons.
Remember:
Famous ringed planet = Saturn
⑦ Uranus
Uranus is the seventh planet from the Sun.
It is a very cold planet.
It appears blue-green because of gases in its atmosphere.
Uranus is tilted greatly on its axis.
It also has rings and natural satellites.
Remember:
Highly tilted planet = Uranus
⑧ Neptune
Neptune is the eighth and farthest planet from the Sun.
It appears blue.
It is a very cold planet.
Very strong winds occur on Neptune.
It has rings and natural satellites.
Remember:
Farthest planet from the Sun = Neptune
🌙 5. Natural Satellite
A natural satellite is a celestial body that revolves around a planet.
Example:
The Moon is the natural satellite of Earth.
Some planets have many moons, while some planets have no natural satellites.
🌙 6. The Moon
The Moon is Earth's natural satellite.
Important points:
The Moon does not produce its own light.
It shines because it reflects sunlight.
Its surface has many holes and depressions called craters.
The Moon has almost no atmosphere.
The Moon takes about 27.3 days to orbit Earth.
The changing shapes of the Moon that we see are called phases of the Moon.
☄️ 7. Comets
A comet is a small celestial body made mainly of ice, dust and rocky material.
When a comet comes close to the Sun, heat causes material from it to form a glowing coma and often a tail.
Important point:
The tail of a comet generally points away from the Sun.
☄️ 8. Asteroids
Asteroids are small rocky or metallic objects that move around the Sun.
Most asteroids are found in the region between Mars and Jupiter.
This region is called the Asteroid Belt.
Remember:
Asteroid Belt = Between Mars and Jupiter
🌠 9. Meteors and Meteorites
A small piece of rock or metal travelling through space is called a meteoroid.
When a meteoroid enters Earth's atmosphere and produces a bright streak of light, it is called a meteor.
If a part of it reaches the Earth's surface, it is called a meteorite.
Easy to remember:
Meteoroid → enters atmosphere → Meteor → reaches ground → Meteorite
🌌 10. Galaxy
A galaxy is a huge collection of stars, gas, dust and other celestial objects held together by gravity.
Our Solar System is a part of the Milky Way Galaxy.
Remember:
Our Solar System → Milky Way Galaxy
🪐 11. Inner and Outer Planets
Inner Planets
The first four planets are called the inner planets:
Mercury, Venus, Earth and Mars
They are also called terrestrial or rocky planets.
Features:
They are relatively small.
They have rocky surfaces.
They are closer to the Sun.
Outer Planets
The last four planets are called the outer planets:
Jupiter, Saturn, Uranus and Neptune
They are much larger than the inner planets.
Features:
They are far from the Sun.
They have thick atmospheres.
Jupiter and Saturn are gas giants.
Uranus and Neptune are ice giants.
⭐ 12. Difference Between a Star and a Planet
| Star | Planet |
|---|---|
| A star produces its own light. | A planet does not produce its own light. |
| A star is very hot. | A planet is much cooler than a star. |
| Stars are made mainly of very hot gases. | Planets can be rocky or made largely of gases and ices. |
| The Sun is a star. | Earth is a planet. |
📌 13. Important Facts to Remember
The centre of our Solar System is the Sun.
There are 8 planets in our Solar System.
The nearest planet to the Sun is Mercury.
The smallest planet is Mercury.
The hottest planet is Venus.
The third planet from the Sun is Earth.
Earth is called the Blue Planet.
The Red Planet is Mars.
The largest planet is Jupiter.
Saturn is famous for its rings.
Uranus is highly tilted on its axis.
Neptune is the farthest planet from the Sun.
The natural satellite of Earth is the Moon.
The Asteroid Belt lies between Mars and Jupiter.
Our Solar System is in the Milky Way Galaxy.
The Sun is a star.
A comet may develop a tail when it comes close to the Sun.
A meteorite is a piece of space rock that reaches Earth's surface.
📝 14. Important Questions and Answers
Q1. What is the Solar System?
Answer: The Solar System is a group of the Sun, eight planets, their satellites and other celestial bodies.
Q2. How many planets are there in the Solar System?
Answer: There are eight planets in the Solar System.
Q3. Which planet is nearest to the Sun?
Answer: Mercury is nearest to the Sun.
Q4. Which is the smallest planet?
Answer: Mercury is the smallest planet.
Q5. Which is the hottest planet?
Answer: Venus is the hottest planet.
Q6. Which planet is called the Red Planet?
Answer: Mars is called the Red Planet.
Q7. Which is the largest planet?
Answer: Jupiter is the largest planet.
Q8. Which planet is famous for its rings?
Answer: Saturn is famous for its rings.
Q9. What is the natural satellite of Earth?
Answer: The Moon is the natural satellite of Earth.
Q10. Which is the farthest planet from the Sun?
Answer: Neptune is the farthest planet from the Sun.
Q11. Where is the Asteroid Belt located?
Answer: The Asteroid Belt is located between Mars and Jupiter.
Q12. In which galaxy is our Solar System located?
Answer: Our Solar System is located in the Milky Way Galaxy.
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