Galaxy – Important General Knowledge
A galaxy is a huge collection of stars, planets, gases, dust, and dark matter
held together by gravity. Galaxies are among the largest structures in the universe.
The Milky Way Galaxy is the galaxy in which our Solar System exists. Questions related
to galaxies are important for competitive examinations such as UPSC, SSC, Railway,
Banking, Defence, PSC, and various GK examinations.
Galaxy at a Glance
| Topic |
Information |
| Definition of Galaxy |
A massive system of stars, planets, gases, and dust |
| Galaxy of Earth |
Milky Way Galaxy |
| Estimated Number of Galaxies |
More than 2 Trillion |
| Shape of Milky Way |
Spiral Galaxy |
| Nearest Major Galaxy |
Andromeda Galaxy |
| Center of Milky Way |
Sagittarius A* |
| Contains |
Stars, Nebulae, Planets, Black Holes |
| Galaxy Cluster |
Group of galaxies held by gravity |
| Our Galaxy Group |
Local Group |
| Scientist Who Proposed Milky Way Structure |
Galileo Galilei contributed important observations |
Types of Galaxies
| Galaxy Type |
Important Features |
| Spiral Galaxy |
Has spiral arms; example – Milky Way |
| Elliptical Galaxy |
Oval-shaped with older stars |
| Irregular Galaxy |
No definite shape |
| Barred Spiral Galaxy |
Spiral galaxy with a central bar structure |
Important Galaxies in the Universe
| Galaxy |
Important Fact |
| Milky Way Galaxy |
Galaxy containing our Solar System |
| Andromeda Galaxy |
Nearest major galaxy to Milky Way |
| Triangulum Galaxy |
Part of Local Group |
| Whirlpool Galaxy |
Famous spiral galaxy |
| Sombrero Galaxy |
Known for bright nucleus and dust ring |
Structure of the Milky Way Galaxy
| Part |
Description |
| Galactic Core |
Dense central region of the galaxy |
| Spiral Arms |
Curved arms containing stars and nebulae |
| Galactic Halo |
Outer spherical region around galaxy |
| Disk |
Flat rotating region containing stars |
| Black Hole |
Located at the center of Milky Way |
Important Facts About the Milky Way Galaxy
| Topic |
Information |
| Galaxy Type |
Barred Spiral Galaxy |
| Diameter |
About 100,000 Light Years |
| Number of Stars |
More than 100 Billion |
| Age |
About 13.6 Billion Years |
| Solar System Position |
Orion Arm |
| Center Distance from Earth |
About 26,000 Light Years |
Important Terms Related to Galaxies
| Term |
Meaning |
| Light Year |
Distance travelled by light in one year |
| Nebula |
Cloud of gas and dust in space |
| Black Hole |
Region with extremely strong gravity |
| Constellation |
Group of stars forming patterns |
| Supernova |
Explosive death of a star |
Galaxy and Universe Comparison
| Topic |
Galaxy |
Universe |
| Definition |
Collection of stars and planets |
Everything that exists |
| Size |
Smaller than universe |
Largest known structure |
| Example |
Milky Way |
Observable Universe |
Important Scientists Related to Galaxies
| Scientist |
Contribution |
| Edwin Hubble |
Discovered galaxies beyond Milky Way |
| Galileo Galilei |
Observed Milky Way through telescope |
| Isaac Newton |
Explained gravity |
| Albert Einstein |
Contributed to modern astrophysics |
Important One-Liner GK Facts About Galaxy
| Question |
Answer |
| Galaxy in which Earth exists |
Milky Way Galaxy |
| Nearest major galaxy to Milky Way |
Andromeda Galaxy |
| Shape of Milky Way Galaxy |
Barred Spiral |
| Largest known structure |
Universe |
| Unit used to measure galaxy distances |
Light Year |
| Center of Milky Way contains |
Black Hole |
| Scientist who discovered expanding universe |
Edwin Hubble |
| Group of galaxies near Milky Way |
Local Group |
| Largest galaxy near Milky Way |
Andromeda Galaxy |
| Galaxy means |
Huge collection of stars and matter |