Ncert solutions

Ncert solutions

Grade 8

Stars and the Solar System | Exercise

Question 14

Q 14) 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?

Solution 14:

Many astronomical objects like stars or galaxies are very far away from the earth & giving their distances in the kilometres unit becomes very inconvenient.

Light-year is a large unit and equals the distance travelled by light in one year. Hence, the large distances are expressed in light-years.

1 light-year = 9.46 x 1012 km

If a star is located 8 light-years away from the earth, it means that the distance between the star and the earth is the distance light would travel in eight years.

So, the distance between the earth and star = 8 ✕ (9.46 ✕ 1012) = 7.6 ✕ 1013 km.

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subject-cta

Question 14

Q 14) 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?

Solution 14:

Many astronomical objects like stars or galaxies are very far away from the earth & giving their distances in the kilometres unit becomes very inconvenient.

Light-year is a large unit and equals the distance travelled by light in one year. Hence, the large distances are expressed in light-years.

1 light-year = 9.46 x 1012 km

If a star is located 8 light-years away from the earth, it means that the distance between the star and the earth is the distance light would travel in eight years.

So, the distance between the earth and star = 8 ✕ (9.46 ✕ 1012) = 7.6 ✕ 1013 km.

Still have questions? Our expert teachers can help you out

Book a free class now

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subject-cta
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