The Earth In The Solar System Class 6 Notes

Key Points: Must Remember

• Celestial bodies are all objects visible in the sky, including stars, planets, moon, asteroids, and meteoroids.
• Stars are huge, hot, glowing celestial bodies made of gases, with their own heat and light. The Sun is a star.
• Planets are celestial bodies that orbit a star. They do not have their own heat and light but reflect the light of the star.
• The Solar System consists of the Sun (a star), eight planets, their satellites, asteroids, and meteoroids.
• The Sun is at the center of the Solar System, providing heat and light to all planets.
• Earth is the third planet from the Sun and the only planet known to support life, often called the 'blue planet' due to water.
• The Moon is Earth's only natural satellite.
• Asteroids are small, rocky celestial bodies, found mainly in the asteroid belt between Mars and Jupiter.
• Meteoroids are small pieces of rocks that revolve around the Sun. When they enter Earth's atmosphere, they often burn up, creating 'shooting stars'.
• A Galaxy is a huge system of billions of stars, dust, and gases. Our Solar System is part of the Milky Way Galaxy.

Key Definitions

Celestial Bodies

Objects present in the vast universe, such as stars, planets, moon, asteroids, and meteoroids.

Stars

Large, hot, luminous bodies made of gases that emit their own heat and light. Example: The Sun.

Planets

Celestial bodies that orbit a star in a fixed path (orbit) and do not have their own heat or light. They reflect the light of their star.

Satellite

A celestial body that revolves around a planet. It can be natural (like the Moon) or artificial.

Orbit

The fixed elliptical path along which a planet revolves around the Sun or a satellite revolves around a planet.

Solar System

The family of the Sun, its eight planets, their satellites, and other smaller celestial bodies like asteroids and meteoroids.

Constellation

A group of stars that form a recognisable pattern in the night sky. Example: Ursa Major (Big Bear) or Saptarishi.

Galaxy

A massive system of billions of stars, dust, and gases held together by gravity. Our galaxy is the Milky Way.

Asteroids

Numerous tiny bodies that revolve around the Sun, found mainly between the orbits of Mars and Jupiter.

Meteoroids

Small pieces of rock that move around the Sun. When they fall to Earth, they are called meteors.

Our Solar System: A Cosmic Family

Our Solar System is a wondrous collection of celestial bodies, all bound by the gravitational pull of our central star, the Sun. The Sun, being a star, is a huge sphere of extremely hot gases that provides the ultimate source of heat and light for the entire Solar System. Without the Sun's energy, life on Earth would be impossible.

Around the Sun, eight planets revolve in fixed, elongated paths called orbits. In order from the Sun, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Each planet has its own unique characteristics. For example, Mercury is the closest planet to the Sun, while Neptune is the farthest. Jupiter is the largest planet, and Earth is the only one known to support life, thanks to its ideal distance from the Sun, presence of water, and suitable atmosphere.

Besides planets, the Solar System is home to satellites (natural, like Earth's Moon, or artificial, like human-made spacecraft), asteroids, and meteoroids. The asteroid belt, a region filled with countless small, rocky objects, is located primarily between the orbits of Mars and Jupiter. These are thought to be remnants of a planet that failed to form. Meteoroids are smaller pieces of rock. When they enter Earth's atmosphere, friction causes them to heat up and burn, creating a streak of light often called a 'shooting star'. If they don't burn up completely and hit the Earth's surface, they are called meteorites.

Beyond our Solar System lies a vast universe, home to billions of galaxies. Our Solar System is part of the Milky Way Galaxy, a spiral-shaped galaxy containing billions of stars. It's a reminder of how small our world is in the grand scheme of the cosmos.

Inner vs. Outer Planets

Exam Tip: Remembering Planet Order

A common question in exams is to list the planets in order from the Sun. Use this mnemonic (memory aid) to easily recall their sequence:

My Very Efficient Mother Just Served Us Noodles.

• Mercury
• Venus
• Earth
• Mars
• Jupiter
• Saturn
• Uranus
• Neptune

Also, pay close attention to the definitions of key terms like 'star,' 'planet,' 'satellite,' 'asteroid,' and 'meteoroid' as direct definition questions are frequent.

Practice Questions with Solutions

• Q: What is the primary difference between a star and a planet? A: A star has its own heat and light, while a planet does not; it reflects the light of a star.
• Q: Name the eight planets of our Solar System in order from the Sun. A: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
• Q: Why is Earth called the 'blue planet'? A: Earth is called the 'blue planet' because two-thirds of its surface is covered by water, which gives it a blue appearance from space.
• Q: Where is the asteroid belt located? A: The asteroid belt is located between the orbits of Mars and Jupiter.

Frequently Asked Questions