Question
List the planets of our solar system in order from the Sun. Classify them as inner (terrestrial) and outer (gas giant) planets. What is a constellation? Name two common constellations visible from India.
Solution — Step by Step
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Mnemonic: My Very Educated Mother Just Showed Us Neptune
(Pluto was reclassified as a dwarf planet in 2006.)
graph TD
A["Solar System Bodies"] --> B["Inner/Terrestrial Planets"]
A --> C["Outer/Gas Giant Planets"]
A --> D["Other Bodies"]
B --> E["Mercury, Venus, Earth, Mars"]
B --> F["Small, rocky, dense, few/no moons"]
C --> G["Jupiter, Saturn, Uranus, Neptune"]
C --> H["Large, gaseous, many moons, rings"]
D --> I["Asteroids: between Mars and Jupiter"]
D --> J["Comets: icy bodies with tails"]
D --> K["Dwarf planets: Pluto, Ceres, Eris"]The asteroid belt between Mars and Jupiter separates the two groups.
A constellation is a recognisable group of stars forming a pattern in the sky. There are 88 officially recognised constellations.
Two visible from India:
- Ursa Major (Saptarshi) — seven bright stars forming a “Great Bear” or “Big Dipper” shape; visible in the northern sky
- Orion (Mriga/Hunter) — recognisable by three stars in a row forming the “belt”; visible in winter months
The Pole Star (Dhruv Tara) can be located using Ursa Major — it indicates true north and barely moves in the sky because it is aligned with Earth’s axis.
Why This Works
Stars are massive, hot balls of gas that produce light through nuclear fusion. Planets do not produce their own light — they reflect sunlight. That is why planets appear steadier than stars (stars twinkle due to atmospheric refraction of their point-like light; planets are closer and appear as tiny discs, so the twinkling averages out).
Our Sun is an average-sized star. It appears large and bright only because it is close — about 150 million km away (1 AU). The next nearest star (Proxima Centauri) is 4.2 light-years away. Light from it takes over 4 years to reach us.
Alternative Method
For CBSE exams, know the special features of each planet: Mercury (smallest, closest to Sun), Venus (hottest due to greenhouse effect, rotates backward), Earth (only planet with liquid water and life as we know it), Mars (red planet, has Olympus Mons — tallest mountain in solar system), Jupiter (largest, Great Red Spot), Saturn (famous rings), Uranus (tilted axis — rolls along orbit), Neptune (farthest, strongest winds).
Common Mistake
Calling the Sun a planet or a constellation a galaxy. The Sun is a STAR, not a planet. A constellation is a pattern of stars as seen from Earth — the stars in a constellation may be at very different distances from us and not physically related. A galaxy is a massive collection of stars, gas, and dust bound by gravity (our Milky Way has over 100 billion stars). These are fundamentally different concepts.