These days, communication happens at the speed of light — literally as fast as possible. But space is so big, even speed-of-light messages seem slow.
Talking with space station crew in low Earth orbit takes about a second.
SEE MORE: New Horizons Flyby Will Shed Light On Pluto's Mysteries
When Apollo astronauts landed on the moon, round-trip communications were delayed by 2.7 seconds.
Getting a response from Mars probes can take as long as 48 minutes.
Juno, in orbit around Jupiter? One hour, 36 minutes round-trip.
When New Horizons flew by Pluto, the delay was close to nine hours.
And talking to Voyager I — the most distant human-made object in the universe — now takes more than 37 hours.