Deep Impact (1998)
The Earth is on average, 93 million miles from the Sun. Communication from the spacecraft at the comet, back to Earth, has a 20-second delay, at the speed of light. The Earth is a little more than 8 light-minutes from the Sun, which places the comet pretty close to the Earth at the point of interception, at 3 million miles. Thus, if the Sun suddenly went dark, or exploded, we wouldn't know for over 8 minutes.