Final answer:
c. The correct interpretation of Vega being 26.5 light-years away from Earth is that the light we observe from Vega has been traveling for 26.5 years to reach us.
Step-by-step explanation:
c. When considering the student's question, the correct choice is d) the light we see left Vega 26.5 years ago. A light-year is a measure of distance, which indicates how far light travels in one year. Since Vega is 26.5 light-years away, this means that the light we currently see from Vega was emitted 26.5 years ago and has traveled through space to reach us. None of the other options are correct or relevant to the statement about Vega's distance in light-years.
It's important to note that light-years measure distance, not time. Therefore, we cannot conclude how old Vega is or how many astronomical units away it is based solely on its distance in light-years. For example, one light-year is approximately 9.461 x 1012 kilometers. Using similar logic, when looking at objects in space, we are effectively looking back in time, since the time it takes for light to travel to us equals the distance in light years.