Light year is a measurement of Stellar distances

The correct answer to the question is option 'C', which states that a light year is a measurement of stellar distances. A light year is a unit of length used in astronomy to measure vast distances in space. Here is a detailed explanation of why option 'C' is the correct answer.

What is a light year?
- A light year is the distance that light travels in one year in a vacuum. It is a unit of astronomical distance, not a unit of time.
- Light travels at a speed of approximately 299,792 kilometers per second in a vacuum. In one year, it can cover a distance of about 9.46 trillion kilometers (or about 5.88 trillion miles).

Stellar distances:
- The vastness of the universe and the distances between celestial objects make it impractical to measure them in terms of kilometers or miles.
- Astronomers use the light year as a convenient unit to express these huge distances.
- Since light travels at a constant speed, the distance it covers in one year provides a reliable measurement for astronomical distances between stars, galaxies, and other celestial objects.

Example:
- For example, if a star is located 10 light years away from Earth, it means that the light we see from that star has taken 10 years to reach us.
- This also means that we are observing the star as it was 10 years ago because the light we receive today left the star 10 years ago.

Importance in astronomy:
- The concept of a light year is crucial in understanding the vastness of the universe and the distances between celestial objects.
- It allows astronomers to measure and compare distances between stars, galaxies, and other astronomical phenomena.
- It also helps in estimating the age of the universe and understanding the cosmic timeline.

Conclusion:
In conclusion, a light year is a unit of measurement used in astronomy to express stellar distances. It represents the distance that light travels in one year and is a fundamental concept in understanding the vastness of the universe.