2019 October 12
Explanation:
In an interplanetary first, on July 19, 2013
Earth was photographed on the same day from two other worlds
of the Solar System,
innermost planet Mercury and ringed gas giant Saturn.
Pictured on the left, Earth is the
pale blue dot
just below the rings of Saturn, as captured by the
robotic
Cassini spacecraft then orbiting the
outermost gas giant.
On that same day people across
planet Earth snapped many of their own
of their own pictures of Saturn.
On the right, the
Earth-Moon system is seen against the dark
background of space as captured by the
robotic MESSENGER
spacecraft, then in Mercury orbit.
MESSENGER took its image as part of a search for
small natural satellites of Mercury, moons that would be
expected to be quite dim.
In the
MESSENGER image, the Earth (left) and Moon (right) are overexposed
and
shine brightly with reflected sunlight.
Destined not to return to their home world, both
Cassini
and
Messenger
have since retired from their missions of Solar System exploration.