# Voyager's distance from Earth

If it took Voyager’s radio signal 4 hours to cross the solar system and reach Earth, roughly how far away in AU was Voyager from Earth when it sent that signal?

• I'm voting to close this question as off-topic because it looks like a homework question, and I don't think it belongs here. – Phiteros Sep 2 '16 at 0:39
• @Phiteros: That's a reasonable downvote reason, but "homework" is a close reason on no site that I am aware of, not even SO. – Nathan Tuggy Sep 2 '16 at 0:40
• @NathanTuggy Normally that wouldn't concern me, but I just feel like this question is rather low quality and does not really contribute anything. – Phiteros Sep 2 '16 at 1:08
• @Phiteros Yes, that's what downvotes are for! You close questions that cannot be usefully answered; you downvote questions that aren't worth answering. I considered downvoting until I checked Bing for 4 light hours in au and found nothing useful. – Nathan Tuggy Sep 2 '16 at 1:29
• Plug the same text into Google and the first result is a calculator that can do this conversion... – Hobbes Sep 2 '16 at 8:38

About 29 au away. Speed * time = distance (since speed has units of distance/time). For this problem, the units are as follows: $$C \text{ meters}/\text{second} * 4 \text{ hours} * (60*60) \text{ seconds}/\text{hour} \approx 4*10^{12} \text{ meters} \approx 29 \text{ au}$$ I didn't know the conversion off the top of my head so I used trusty Wolfram Alpha.