## Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?

The distance between the stars is so large that Kilometers becomes a very small unit.

Hence, the distance between stars and planets are expressed in light years .

One Light Year means Distance travelled by light in 1 Year.

Calculating 1 Light Year

Speed of Light = 3 × 10 8 m/s

Time = 1 Year

= 365 days

= 365 × 24 hours

= 31536000 seconds

Now,

1 Light Year = Speed × Time

= 3 × 10 8 × 31536000 m

= 94608000 × 10 8

= 94608000 × 10 8 × 1/000 km

= 94608 × 10 8 km

= 9.4608 × 10 4 × 10 8 km

= 9.4608 × 10 12 km

Now,

A star located 8 light years away means

Distance between star and earth = 8 light years

= 8 × 9.4608 × 10 12 km

= 8 × 9.4608 × 10 12 km

= 75.6874 × 10 12 km

= 7.56874 × 10 13 km

= 7.57 × 10 13 km

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1. Class 8
2. Chapter 17 Class 8 - Stars and the Solar System
3. NCERT Questions

NCERT Questions

Class 8
Chapter 17 Class 8 - Stars and the Solar System 