This latest image from the Cassini spacecraft will make you do a double-take! It is an optical illusion, but the two moons appear like conjoined, identical twins! The two moons are fairly close in size, but Dione, the smaller of the two at the top in the image, is actually closer to the spacecraft, making the two look almost identical. And because of the similar albedo, or reflectivity, of the two moons and because of the location of a particularly large crater near the south polar region of Dione, the moon appears blended seamlessly with Rhea. Double your pleasure!
Dione is 1123 kilometers (698 miles) across and Rhea is 1528 kilometers (949 miles) across.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 27, 2010.