The blue dot on the centre-right of this photograph is us. This picture was taken by NASA’s Cassini probe on 19 July, while the spacecraft’s orbit took it into the shadow of Saturn — meaning that the Sun was eclipsed by the gas giant.
Seen from the outer Solar System, Earth’s orbit looks small and tightly wound around the Sun. To see the planet from Saturn, then, one would have to wait for the rare occasions when the Sun has just set or is about to rise and the Earth happens to hover just above the horizon.
This is similar to what happens with Mercury as seen from Earth: the planet is usually hidden in the Sun’s glare, so that to see it one has to catch it shortly after sunset or shortly before sunrise.
Cassini, which has orbited Saturn since 2004, was able to spot Earth only once before, in 2006. That image, however, was taken with ultraviolet and infrared sensors; this is the first time Cassini has taken a snapshot of our pale blue dot in its true colours.