Solar System and Planets Overview
Delhi Police & SSC Exams Preparation
1. Introduction
The Solar System is our cosmic neighborhood, consisting of the Sun and all the celestial bodies that revolve around it — planets, moons, asteroids, comets, and meteoroids.
Key Facts:
- Central Star: Sun
- Planets: 8 planets in elliptical orbits
- Importance: 1–2 PYQs in Delhi Police exam
- Scope: Geography & General Science
Significance:
Fundamental topic for understanding our cosmic environment and planetary science
Exam Trick: "Sun is the King, Planets are the Subjects"
2. The Sun – The Center of the Solar System
Key Facts:
- Type: Medium-sized star
- Mass: 99.86% of Solar System's total mass
- Composition: Hydrogen (≈71%) & Helium (≈27%)
- Energy Source: Nuclear fusion of hydrogen into helium
- Temperature: Core ≈ 15 million °C, Surface ≈ 5,500 °C
Role:
Provides light and heat to all planets, governing the Solar System
Exam Trick: "Hydrogen + Helium = Solar Premium"
3. The Planets
Basic Information:
- Total Planets: 8 planets
- Orbit Type: Elliptical orbits around Sun
- Direction: Counterclockwise revolution
- Order: Mercury – Venus – Earth – Mars – Jupiter – Saturn – Uranus – Neptune
Classification:
Planets divided into Inner (Terrestrial) and Outer (Jovian) categories
Exam Trick: "My Very Efficient Mother Just Served Us Noodles"
4. Division of Planets
| Category | Planets | Characteristics |
|---|---|---|
| Inner (Terrestrial) Planets | Mercury, Venus, Earth, Mars | Small, rocky, dense, few or no moons |
| Outer (Jovian/Gas Giants) | Jupiter, Saturn, Uranus, Neptune | Large, gaseous, many moons, rings present |
Exam Trick: "Inner = Rocky, Outer = Gassy"
5. Key Facts about Each Planet
| Planet | Position from Sun | Special Features |
|---|---|---|
| Mercury | 1st | Smallest, closest to Sun, no atmosphere |
| Venus | 2nd | Brightest planet, hottest surface, "Earth's twin" |
| Earth | 3rd | Only planet with life, oxygen, and water |
| Mars | 4th | "Red Planet", has two moons – Phobos & Deimos |
| Jupiter | 5th | Largest planet, Great Red Spot, many moons |
| Saturn | 6th | Known for its rings, least dense planet |
| Uranus | 7th | Rotates on its side (98° tilt), bluish-green |
| Neptune | 8th | Farthest, coldest, strong winds, blue color |
Exam Trick: "Men Visit Every Market Just Selling Umbrella Now"
6. Dwarf Planets
| Dwarf Planet | Region | Remark |
|---|---|---|
| Pluto | Kuiper Belt | Reclassified in 2006 by IAU |
| Eris | Beyond Pluto | Second largest dwarf planet |
| Ceres | Asteroid Belt | Closest dwarf planet to Earth |
| Haumea & Makemake | Kuiper Belt | Odd-shaped, icy objects |
Exam Trick: "PCHEM – Pluto, Ceres, Haumea, Eris, Makemake"
7. Other Members of the Solar Family
Celestial Bodies:
- Satellites (Moons): Natural bodies revolving around planets
- Asteroids: Small rocky objects in Asteroid Belt (Mars & Jupiter)
- Meteoroids: Small rocks in space
- Meteors: Shooting stars (burn in atmosphere)
- Meteorites: Reach Earth's surface
- Comets: Ice, dust, gases (Halley's Comet - 76 years)
Key Locations:
Asteroid Belt between Mars and Jupiter
Kuiper Belt beyond Neptune
Exam Trick: "Asteroids = Rocks, Comets = Ice"
8. Orbits and Rotation
| Planet | Rotation Period | Revolution Period |
|---|---|---|
| Mercury | 59 days | 88 days |
| Venus | 243 days (retrograde) | 225 days |
| Earth | 24 hrs | 365 days |
| Mars | 24 hrs 37 min | 687 days |
| Jupiter | 10 hrs | 12 years |
| Saturn | 10.7 hrs | 29 years |
| Uranus | 17 hrs | 84 years |
| Neptune | 16 hrs | 165 years |
Exam Trick: "Closer = Faster Revolution"
9. Quick Comparison – Inner vs Outer Planets
| Feature | Inner Planets | Outer Planets |
|---|---|---|
| Composition | Rocky | Gaseous |
| Size | Small | Large |
| Moons | Few or none | Many |
| Rings | None | Present |
| Examples | Mercury, Venus, Earth, Mars | Jupiter, Saturn, Uranus, Neptune |
Exam Trick: "Inner = Near & Rocky, Outer = Far & Gassy"
PYQs (Delhi Police + SSC + State Exams)
Which planet is known as the "Red Planet"?
Options: (a) Venus (b) Mars (c) Jupiter (d) Mercury
Category: Planetary Features
Show Answer
Mars
Which is the brightest planet in the Solar System?
Options: (a) Jupiter (b) Venus (c) Saturn (d) Neptune
Category: Planetary Features
Show Answer
Venus
The planet which rotates from East to West is —
Options: (a) Earth (b) Mars (c) Venus (d) Mercury
Category: Planetary Rotation
Show Answer
Venus
Which planet is known as the "Earth's Twin"?
Options: (a) Venus (b) Mars (c) Jupiter (d) Saturn
Category: Planetary Comparisons
Show Answer
Venus
The largest planet in our Solar System is —
Options: (a) Earth (b) Jupiter (c) Saturn (d) Neptune
Category: Planetary Size
Show Answer
Jupiter
Which planet is known for its rings?
Options: (a) Uranus (b) Jupiter (c) Saturn (d) Neptune
Category: Planetary Features
Show Answer
Saturn
Which is the smallest planet in the Solar System?
Options: (a) Mars (b) Mercury (c) Venus (d) Pluto
Category: Planetary Size
Show Answer
Mercury
The only planet known to support life is —
Options: (a) Earth (b) Mars (c) Jupiter (d) Venus
Category: Planetary Features
Show Answer
Earth
The asteroid belt lies between —
Options: (a) Mars and Jupiter (b) Earth and Mars (c) Jupiter and Saturn (d) Venus and Earth
Category: Solar System Structure
Show Answer
Mars and Jupiter
Halley's Comet appears after every —
Options: (a) 50 years (b) 76 years (c) 100 years (d) 25 years
Category: Comets
Show Answer
76 years
Final Exam Tip
Focus on Venus – Hottest & Brightest (most asked in Delhi Police). Remember Jupiter – Largest, Mercury – Smallest, Saturn – Rings. Order of planets is asked almost every year! Remember Asteroid Belt between Mars and Jupiter. Halley's Comet – 76 years, must memorize.
Master Solar System for Delhi Police Exam!
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