You have taken a picture of a galaxy 1 billion light years away. That picture shows
A)a galaxy that is 1 billion light years old.
B)a galaxy that is 1 billion years old.
C)a galaxy that is 13 billion years old.
D)a galaxy as it was 1 billion years ago.

Question

Quizplus · Accepted Answer

Since light travels at a finite speed, it takes time for the light from distant galaxies to reach us on Earth. Therefore, when we observe a galaxy that is 1 billion light years away, we are seeing it as it was 1 billion years ago. This means that the galaxy could be much older than 1 billion years, but we can only see it as it was 1 billion years ago.

You Have Taken a Picture of a Galaxy 1 Billion