Starlight observation allows the study of which of the following?

• A. Starlight allows observation of past events based on light travel time.
• B. Starlight reveals future events as they occur.
• C. Starlight is unrelated to astronomy.
• D. Starlight only comes from the Sun.

Answer: (B)

Light travels at a finite speed, so when we observe starlight, we’re looking back in time. The light we see from a distant star or galaxy left it years, or even millions of years, ago. That means starlight lets us study events that happened in the past, not the present or the future. For example, the Sun’s light takes about eight minutes to reach Earth, and light from faraway stars shows us what they were like long ago. That’s why starlight is a powerful way to understand cosmic history. The idea that we can see future events as they occur isn’t possible because we would need light from events that haven’t happened yet to reach us. Also, starlight isn’t only from the Sun—many stars and other luminous objects contribute light, all central to astronomy.