Final answer:
The best thing to measure using light years is the distance between stars.
Step-by-step explanation:
The best thing to use light years to measure is the distance between stars. A light year is the distance that light travels in one year, which is equivalent to approximately 9.46 trillion kilometers or 5.88 trillion miles. Since stars are extremely far apart from each other, measuring their distances using conventional distance units like kilometers or miles would be impractical. Light years provide a convenient and accurate way to express the vast distances between stars.
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