This is one of my favorite Cassini images.
A brief explanation from Wikipedia:
On July 19, 2013, in an event celebrated the world over, NASA's Cassini spacecraft slipped into Saturn's shadow and turned to image the planet, seven of its moons, its inner rings -- and, in the background, our home planet, Earth. This mosaic is special as it marks the third time our home planet was imaged from the outer solar system; the second time it was imaged by Cassini from Saturn's orbit; and the first time ever that inhabitants of Earth were made aware in advance that their photo would be taken from such a great distance.
In the lower right of the mosaic, in between the bright blue E ring and the faint but defined G ring, is the pale blue dot of our planet, Earth.
Here is the photo. You can enlarge it enough to play around with it and see the tiny dots of the planets. Though I admit I find it difficult to work out whether I've seen a planet or been confused by a star.
This helps to locate Earth on the other photos.