Back on May 8th, 2003, the Mars Orbiter Camera on the Mars Global
Surveyor photographed both the Earth and
Jupiter in the same region of space. It was the first planetary
conjunction observed from another planet, with the Earth 86 million
miles away and Jupiter 600 million miles away. The resulting image
(shown above right), contains both planets, along with some of the
moons.
Here’s a higher-res version of the photograph:
The three moons of Jupiter seen in the photograph are Callisto, Ganymede, and Europa (from left to right).