Explanation:
What is humanity's most distant spacecraft?
Launched in 1977,
Voyager 1 now
holds that distinction
at 17.5 billion kilometers from the Sun.
That corresponds to 16
light-hours or 117
Astronomical Units (AU).
This
graphic shows the position of Voyager 1 relative to the outer
solar system (top and side views) along with other distant
spacecraft contenders.
Next most distant,
Pioneer 10 is about 15.4 billion kilometers from the
Sun, though on the opposite side of the solar system from Voyager 1.
Voyager 2 and Pioneer 11, both also well beyond the orbit of Pluto, are
14.2 billion and 12.4 billion kilometers from the Sun respectively.
Still outbound for Pluto, the
New Horizons spacecraft is presently
3 billion kilometers from the Sun and will encounter the
Pluto system in July of 2015.
All these spacecraft have used sling-shot style
gravity
assist maneuvers to increase
their speeds through the
outer solar system.
Voyager 1 is moving the fastest though, escaping the solar system
at about 17 kilometers per second.
Still
operational, both Voyagers are headed towards
the outer boundary of the solar system,
in search of the heliopause and the
beginning of interstellar space.
