Much as its name implies, tiny Epimetheus (Greek for hindsight) was discovered in hindsight. Astronomers originally thought that Janus and Epithemeus were the same object. Only later did astronomers realize that there are in fact two bodies sharing the same orbit!
Janus (111 miles or 179 kilometers across) and Epimetheus (70 miles or 113 kilometers) have the same average distance from Saturn, but they take turns being a little closer or a little farther from Saturn, swapping positions approximately every 4 years. See PIA 08348 for more.
This view looks toward the sunlit side of the rings from about 29 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 1, 2015.
The view was acquired at a distance of approximately 1.8 million miles (2.9 million kilometers) from Epimetheus and at a Sun-Epimetheus-spacecraft, or phase, angle of 89 degrees. Image scale is 11 miles (17 kilometers) per pixel.
The Cassini Solstice Mission is a joint United States and European endeavor. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.