The Solar System is a collection of celestial bodies bound together by the gravitational force of the Sun. It consists of the Sun, eight planets, their natural satellites, dwarf planets, asteroids, comets, meteoroids, and interplanetary dust. Questions related to the Solar System are frequently asked in NDA, CDS, AFCAT, CAPF, SSC, and other competitive examinations.
NDA & CDS 2 2026 Exam GK- Geography – Solar System
What is the Solar System?
The Solar System is a planetary system centered around the Sun. The Sun contains nearly 99.8% of the total mass of the Solar System and provides light and heat to all planets.
Main Components of the Solar System
- Sun
- Eight Planets
- Natural Satellites (Moons)
- Dwarf Planets
- Asteroids
- Comets
- Meteoroids
- Interplanetary Dust and Gas
The Sun
The Sun is a medium-sized star located at the center of the Solar System.
Important Facts
- Composed mainly of Hydrogen and Helium.
- Source of energy through nuclear fusion.
- Diameter: Approximately 1.39 million km.
- Surface Temperature: About 5,500°C.
- Core Temperature: Around 15 million°C.
- Light from the Sun takes approximately 8 minutes 20 seconds to reach Earth.
Planets of the Solar System
The planets revolve around the Sun in elliptical orbits.
Order of Planets from the Sun
- Mercury
- Venus
- Earth
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune
Mnemonic
My Very Efficient Mother Just Served Us Noodles
Inner Planets (Terrestrial Planets)
These planets are rocky and lie close to the Sun.
Mercury
- Closest planet to the Sun.
- Smallest planet in the Solar System.
- No natural satellite.
- Fastest revolution around the Sun (88 days).
Venus
- Known as Earth’s twin.
- Hottest planet due to a thick carbon dioxide atmosphere.
- Rotates from east to west.
- No natural satellite.
Earth
- Known as the Blue Planet.
- Only known planet supporting life.
- About 71% covered by water.
- One natural satellite – the Moon.
Mars
- Called the Red Planet.
- Presence of iron oxide gives reddish color.
- Has two moons: Phobos and Deimos.
- Home to Olympus Mons, the largest volcano in the Solar System.
Outer Planets (Jovian Planets)
These are giant gaseous planets.
Jupiter
- Largest planet in the Solar System.
- Known for the Great Red Spot.
- Has the maximum number of known moons among major planets.
Saturn
- Famous for its spectacular ring system.
- Second-largest planet.
- Least dense planet.
Uranus
- Rotates on its side.
- Appears blue-green due to methane gas.
- Coldest planetary atmosphere.
Neptune
- Farthest planet from the Sun.
- Known for extremely strong winds.
- Deep blue in appearance.
Dwarf Planets
Dwarf planets orbit the Sun but do not clear their orbital path.
Major Dwarf Planets
- Pluto
- Ceres
- Eris
- Haumea
- Makemake
Pluto
- Formerly the ninth planet.
- Reclassified as a dwarf planet by the International Astronomical Union (IAU) in 2006.
Asteroids
Asteroids are rocky objects revolving around the Sun.
Asteroid Belt
- Located between Mars and Jupiter.
- Contains millions of rocky bodies.
- Largest asteroid: Ceres.
Comets
Comets are celestial bodies made of ice, dust, and gases.
Features
- Develop a tail when approaching the Sun.
- Tail always points away from the Sun.
- Famous comet: Halley’s Comet.
Meteoroids, Meteors and Meteorites
Meteoroid
A small rocky object moving through space.
Meteor
A meteoroid that burns upon entering Earth’s atmosphere and appears as a “shooting star.”
Meteorite
A meteor that reaches Earth’s surface without completely burning up.
Important Terms
Revolution
Movement of a planet around the Sun.
Rotation
Spinning of a planet on its own axis.
Orbit
The path followed by a planet around the Sun.
Satellite
A celestial body that revolves around a planet.
Important Records of the Solar System
| Feature | Planet/Object |
|---|---|
| Closest to Sun | Mercury |
| Farthest Planet | Neptune |
| Largest Planet | Jupiter |
| Smallest Planet | Mercury |
| Hottest Planet | Venus |
| Fastest Planet | Mercury |
| Largest Moon | Ganymede |
| Planet with Rings | Saturn |
| Red Planet | Mars |
| Blue Planet | Earth |
| Earth’s Twin | Venus |
| Coldest Planet Atmosphere | Uranus |
Recent Space Exploration Highlights
Modern space agencies continue to explore the Solar System through advanced missions.
Important Space Agencies
- ISRO (India)
- NASA (USA)
- ESA (Europe)
- Roscosmos (Russia)
- CNSA (China)
India’s Achievements
- Chandrayaan Missions
- Aditya-L1 Solar Mission
- Mangalyaan (Mars Orbiter Mission)
- Gaganyaan Human Spaceflight Programme
NDA & CDS Exam Tips
- Memorize the order of planets.
- Learn important planetary nicknames.
- Remember the largest, smallest, hottest, and coldest planets.
- Revise dwarf planets and asteroid belt facts.
- Focus on recent Indian space missions and achievements.
Quick Revision
- Total Planets: 8
- Largest Planet: Jupiter
- Smallest Planet: Mercury
- Hottest Planet: Venus
- Red Planet: Mars
- Blue Planet: Earth
- Planet with Prominent Rings: Saturn
- Closest Planet to Sun: Mercury
- Farthest Planet: Neptune
- Largest Moon: Ganymede
- Dwarf Planet: Pluto
Conclusion
The Solar System forms an important part of Geography and General Science for NDA and CDS examinations. Questions are regularly asked about planets, satellites, dwarf planets, comets, and space missions. Thorough revision of planetary characteristics and key astronomical facts can significantly improve performance in the examination.
