Chapter 12 — Beyond Earth

Chapter 12 of the Class 6 Science NCERT textbook (Curiosity), "Beyond Earth", introduces students to stars, constellations, the Solar System, the Moon, asteroids, comets, the Milky Way Galaxy, and the Universe.

• Stars and constellations — Constellations are defined regions of sky, often with recognisable star patterns, and the IAU officially lists 88 of them. Before the compass, star patterns guided navigation — the Pole Star stays nearly fixed in the north to show direction.
• The Sun and the planets — The Sun is a star of hot gases about 100 times wider than Earth, 150 million km away. Eight planets orbit it — the inner four small and rocky, the outer four giant gas-and-ice worlds with rings — including our own Blue Planet, Earth.
• The Moon, asteroids and comets — The Moon, Earth's satellite about 3,84,000 km away, revolves in about 27 days and bears craters from impacts; Chandrayaan-3 soft-landed near its south pole. Asteroids cluster in a belt between Mars and Jupiter, and comets of dust, gas, rock and ice grow tails near the Sun.
• Galaxies and the Universe — Our Solar System sits within the Milky Way Galaxy (Akasha Ganga), which holds millions to billions of stars. Countless other galaxies fill the vast Universe, where scientists search exoplanets for signs of life.

1. 01Constellations are defined sky regions often containing recognisable star patterns; the IAU officially listed 88 constellations.
2. 02Star patterns were used for navigation before the magnetic compass; the Pole Star (Polaris/Dhruva tara) appears nearly stationary in the North and helps find direction.
3. 03Sirius in Canis Major is the brightest star in the night sky; Orion (the hunter) is best viewed in India from December to April.
4. 04The Sun is a star — a hot spherical ball of gases about 100 times bigger than Earth in diameter, located 150 million km (1 au) from Earth.
5. 05The eight planets in order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Inner four are small with rocky surfaces; outer four are giant gas-and-ice planets with ring structures.
6. 06Venus is called the Morning/Evening Star; Mars is the Red Planet; Earth is the Blue Planet (appears blue from space due to water cover).
7. 07The Moon is Earth's natural satellite, about 3,84,000 km away and about 1/4 the size of Earth in diameter, completing one revolution in about 27 days.
8. 08Chandrayaan-3 (July 2023) made India the first country to soft-land near the Moon's south pole on 23 August 2023, now celebrated as National Space Day.
9. 09Asteroids are small rocky irregular objects; the asteroid belt lies between Mars and Jupiter. Comets are made of dust, gases, rocks and ice and develop a tail when approaching the Sun.
10. 10Our Solar System is part of the Milky Way Galaxy (Akasha Ganga), which has millions to billions of stars. There are many galaxies in the Universe beyond our own.