Voyager 1 launches from Cape Canaveral, Florida aboard a Titan-Centaur rocket. It's the second of the twin Voyager probes to launch, but the first to reach the outer planets due to its faster trajectory.

Voyager 1 passes its twin, Voyager 2, which launched 16 days earlier but on a slower trajectory.

Closest approach to Jupiter at 349,000 km. Voyager 1 discovers a thin ring system around Jupiter and active volcanism on the moon Io — the first time volcanic activity was observed beyond Earth.

Voyager 1's cameras detect plumes from volcanoes on Io, one of the most dramatic planetary discoveries of the 20th century. Nine active volcanoes are observed erupting simultaneously.

Closest approach to Saturn. Voyager 1 studies Saturn's rings in unprecedented detail and makes a targeted flyby of Titan — Saturn's largest moon and the only moon in the solar system with a dense atmosphere. The Titan flyby bends Voyager 1's trajectory out of the ecliptic plane, ending its planetary mission.

Voyager 1 passes within 6,500 km of Titan, revealing a thick nitrogen atmosphere with organic chemistry. Scientists detect complex carbon compounds — the building blocks of life.

At Carl Sagan's request, Voyager 1 turns its camera back toward the inner solar system and photographs Earth from 6.4 billion km — the famous "Pale Blue Dot" image. It is Voyager 1's last photograph.

Voyager 1 overtakes Pioneer 10 to become the most distant human-made object in space, a title it still holds.

Voyager 1 crosses the termination shock — the point where the solar wind slows to subsonic speeds. It has reached the heliosheath, the outermost region of the Sun's influence.

Voyager 1 crosses the heliopause and officially enters interstellar space — becoming the first human-made object to leave the solar system. Plasma data confirms the crossing.

Scientists analyze the 2012 data and formally confirm Voyager 1 is in interstellar space. Measurements of plasma density match the density expected outside the heliosphere.

Engineers fire Voyager 1's trajectory correction maneuver thrusters for the first time since 1980 to help orient the spacecraft's antenna toward Earth. They work perfectly.

Voyager 1 will be one full light-day from Earth — meaning radio signals will take 24 hours to travel between us.

Voyager 1 will pass within 1.7 light-years of the star AC+79 3888 in the constellation Camelopardalis.