The Voyager1 spacecraft is the farthest man-made object from Earth; as of January 4th, 2012, Voyager1 is about 17.856 billion km from the Sun.
Radio signals from Voyager 1 take 16.12 hours to reach the Earth.
Voyager 1's current relative velocity to the Sun is 61400 km/hr: 73600 years would pass before reaching the nearest star, Proxima Centauri, were the spacecraft travelling in that direction.