Beyond Earth | Class 6 Science Notes

12.3 Our Solar System

The Sun is a star and the closest star to Earth. It is an extremely hot, spherical ball of gases that produces a huge amount of energy through nuclear fusion reactions in its core. This energy is emitted as heat and light, making the Sun glow brightly and serving as the main source of energy for Earth. The Sun is about 100 times bigger than Earth in diameter but appears small because it is very far away, approximately 150 million kilometers from Earth. This distance is called one astronomical unit (au), a useful unit for expressing distances within the Solar System. The Sun's heat keeps Earth at a temperature suitable for life and drives climate, seasons, weather, and the water cycle. Earth, along with other objects such as planets and moons, forms the Solar System. A planet is a large, nearly spherical object that revolves around the Sun. Earth takes about one year to complete one revolution around the Sun. Additionally, Earth rotates about its axis once every 24 hours, creating day and night. Other planets also revolve around the Sun and rotate about their axes. The eight planets, in order of increasing distance from the Sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The inner four planets (Mercury, Venus, Earth, Mars) are smaller with rocky surfaces, while the outer four (Jupiter, Saturn, Uranus, Neptune) are larger gas and ice giants with ring systems. Venus is often called the Morning Star or Evening Star due to its bright appearance at dawn or dusk. Mars is known as the Red Planet because of its reddish soil. Earth is called the Blue Planet because of its water-covered surface. Pluto, once considered the ninth planet, is now classified as a dwarf planet by the International Astronomical Union (IAU) due to its small size and other criteria.

📊 Diagram: Fig. 12.6: The rising Sun; However, the Sun is much closer to us than the other stars hence it appears much bigger than the stars. As the stars (other than the Sun) are much farther away, they appear like points, even though so; There are many more objects in the sky. Our Earth, along with some of these objects, and the Sun together form our Solar System (Fig. 12.7). Most of these objects move around the Sun. The movement of ; More to know!; Fig. 12.7: An artist's representation of the Solar System

🔗 Connection: This section introduces the Sun and planets, leading to details about natural satellites and other smaller objects in the Solar System.

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