The Andromeda Galaxy is located approximately 2.5 million light-years away from Earth. If a massive…
The Andromeda Galaxy is located approximately 2.5 million light-years away from Earth. If a massive supernova stellar explosion happens in Andromeda right now, when will astronomers on Earth be able to see it?
Instantly today
In 2.5 years
In 2,500 years
In 2.5 million years
Solution
Light travels at 1 light-year per year, so light emitted from an object 2.5 million light-years away takes 2.5 million years to reach Earth.