Chapter 12
🌌 Beyond Earth
Curiosity | NCERT Grade 6 Science
📚 Table of Contents
📷 The beautiful night sky from Ladakh — thousands of visible stars
⭐ 12.1 Stars and Constellations
📖 What are Stars?
Stars are huge balls of hot, glowing gases that produce their own light and heat through nuclear reactions. They are extremely far away — even the closest star (other than the Sun) is over 4 light-years away! ⭐ What is a Constellation?
A constellation is a group of stars that appear to form a pattern when viewed from Earth. These patterns were named by ancient astronomers who saw shapes of animals, objects, or mythological characters. | Constellation | Pattern looks like | Visible When |
|---|---|---|
| ⭐ Orion | A hunter with a belt of 3 stars | December to April (India) |
| 🐻 Ursa Major (Big Dipper/Saptarishi) | A big ladle/dipper, 7 stars | Summer nights (North) |
| 🐻 Ursa Minor (Little Dipper) | A small ladle; contains Pole Star | Year-round (Northern hemisphere) |
| 🐂 Taurus | A bull | Winter nights |
| 🐕 Canis Major | A big dog; contains Sirius | Winter nights |
📷 Constellations — Orion, Taurus and Canis Major with star patterns
🌟 Indian Astronomy — Nakshatra
In Indian astronomy, the term Nakshatra refers to a star or group of stars. Examples: Ārdrā (star Betelgeuse in Orion), Kṛittikā (Pleiades in Taurus), Rohiṇī (Aldebaran in Taurus). The Saptarishi (Big Dipper) and Dhruva tārā (Pole Star/Polaris) are well-known in Indian culture!Pole Star (Polaris / Dhruva tārā) — appears almost stationary in the night sky, always in the North direction! Used for navigation since ancient times. It is part of the Little Dipper (Ursa Minor).
How to find the Pole Star:
1
Find the Big Dipper (7 stars in ladle shape)
2
Look at the 2 stars at the far end of the ladle's cup
3
Draw an imaginary line through these 2 stars toward the North
4
Go about 5 times the distance between these stars → you'll find the Pole Star!
🔭 12.2 Night Sky Watching
- Best viewed from dark areas away from city lights — light pollution reduces visibility
- Wait about 30 minutes after going out for eyes to adjust to darkness
- Use sky mapping apps (e.g., Sky Map, Stellarium — free for download)
- The Moon and clouds reduce star visibility
- Always go with an adult; do NOT go to dark areas alone at night
💡 Light Pollution
The presence of excessive artificial light at night is called light pollution. It reduces our ability to see stars. Some countries have set up dark sky reserves to protect areas from light pollution for astronomical research!☀️ 12.3 Our Solar System — The Sun
☀️ The Sun
The Sun is a star — the star closest to Earth. It is an extremely hot, spherical ball of gases that produces enormous heat and light through nuclear reactions. - Distance from Earth: about 150 million km (1 astronomical unit / 1 AU)
- Size: about 100 times bigger than Earth in diameter
- The Sun's energy drives life on Earth — photosynthesis, water cycle, winds
- In ancient India, the Sun is worshipped as Sūrya
1 Astronomical Unit (AU) ≈ 150 million km
(Distance between Earth and Sun)
(Distance between Earth and Sun)
🪐 12.4 Planets of the Solar System
📖 What is a Planet?
A planet is a large body that orbits (goes around) the Sun, has enough gravity to be roughly round, and has cleared the neighbourhood around its orbit. 
📷 Our Solar System — planets orbiting the Sun
| Planet | Key Feature | Distance from Sun |
|---|---|---|
| ☿ Mercury | Smallest planet; closest to Sun; extreme temperature | ~0.39 AU |
| ♀️ Venus | Hottest planet; brightest in sky; covered in clouds | ~0.72 AU |
| 🌍 Earth | Our home; only known planet with life; has Moon | ~1 AU |
| ♂️ Mars | Red planet; dust storms; 2 moons; thin atmosphere | ~1.52 AU |
| ♃ Jupiter | Largest planet; Great Red Spot (giant storm); 90+ moons | ~5.2 AU |
| ♄ Saturn | Beautiful rings; least dense planet; many moons | ~9.5 AU |
| ♅ Uranus | Rotates on its side; icy planet; blue-green colour | ~19.2 AU |
| ♆ Neptune | Farthest planet; strongest winds; deep blue colour | ~30 AU |
🪐 What about Pluto?
Pluto was once considered the 9th planet but in 2006 was reclassified as a "dwarf planet" by the International Astronomical Union (IAU) because it hasn't cleared its orbital neighbourhood.Memory trick for planet order:"My Very Educated Mother Just Served Us Nachos" → Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune 🪐
🌙 Moon & Satellites
- A moon (natural satellite) is a body that orbits a planet
- Earth has 1 moon; Jupiter has the most (90+); Mercury & Venus have none
- Artificial satellites are man-made objects placed in orbit (used for GPS, weather, communication)
🌌 12.5 The Milky Way Galaxy
📖 What is a Galaxy?
A galaxy is a vast collection of billions of stars, gas, and dust held together by gravity. - Our Solar System is part of the Milky Way galaxy
- The Milky Way contains about 200-400 billion stars
- It is a spiral galaxy — shaped like a spiral/pinwheel
- Our Sun is located in one of the spiral arms
- The Milky Way appears as a bright band of light across the night sky
- It is called Ākāśagaṅgā in Sanskrit/Hindi
📷 The Milky Way Galaxy — our home galaxy
✨ 12.6 The Universe
📖 The Universe
The Universe is everything that exists — all matter, energy, space, and time. It contains billions of galaxies, each with billions of stars! - The Universe is about 13.8 billion years old
- The Universe began with the Big Bang — a massive explosion of energy
- The Universe is still expanding — galaxies are moving away from each other
- There are an estimated 2 trillion (2×10¹²) galaxies in the observable universe
Planets → Solar System → Milky Way Galaxy → Universe
(smallest to largest scale)
(smallest to largest scale)
📝 Chapter Summary
- Stars = hot, glowing balls of gas producing own light; very far away
- Constellation = pattern of stars seen from Earth (Orion, Big Dipper, etc.)
- Pole Star (Dhruva tārā) = nearly stationary star pointing North; used for navigation
- Solar System = Sun + 8 planets + moons + asteroids + comets
- Planets in order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
- Earth = only known planet with life; 1 moon; 3rd from Sun
- Milky Way = our spiral galaxy with ~300 billion stars
- Universe = everything that exists; ~13.8 billion years old; still expanding
Advertisement
⬇ Download PDF
Comments & Doubts
Abhi tak koi comment nahi
Sabse pehle comment karne wale bano!
Apna comment likhein
Doubt ho ya suggestion — kuch bhi poochh sakte hain. Login zaroori nahi hai.