- Stars are located light years apart from each other
- Light years ly are an astronomy unit used for measuring length / distance generally used for values between 1 and 27000000000
- Therefore, light year is used to measure the distance between stars

So, light year is used to measure the distance between stars
Q: What unit do scientists use to measure the distance between stars?
Context:
- Stars are located light years apart from each other 
- Light years ly are an astronomy unit used for measuring length / distance generally used for values between 1 and 27000000000