Death Star Lookalike

View from Afar

Saturn’s moon Mimas (left) compared to the fictional 1977 Star Wars ‘Death Star’, (right) which used its large depression as a ‘superlaser focus lens’ to exact planet-scale revenge. Image Credit: NASA/JPL

Lonely Mimas swings around Saturn, seeming to gaze down at the planet’s splendid rings. The outermost, narrow F ring is visible here and exhibits some clumpy structure near the bottom of the frame. The shadow of Saturn’s southern hemisphere stretches almost entirely across the rings. Mimas is 398 kilometers (247 miles) wide.

The image was taken with the Cassini spacecraft narrow angle camera on August 15, 2004, at a distance of 8.8 million kilometers (5.5 million miles) from Saturn, through a filter sensitive to visible red light. The image scale is 53 kilometers (33 miles) per pixel. Contrast was slightly enhanced to aid visibility.

The enormous crater at the top of the right image, named Herschel, is about 130 kilometers (80 miles) wide and 10 kilometers (6 miles) deep. Deeper than the Grand Canyon, Herschel stretches across nearly a third of the tiny moon’s diameter. The central mountain shown at the center of Hershel is the height of Mount Everest on Earth.

Fine surface texture of Saturn’s satellite, Mimas, in different lighting conditions from the Voyager I camera in November 1980.

This impact probably came close to disintegrating the moon. Traces of fracture marks can be seen on the opposite side of Mimas, suggesting that the destruction nearly split the satellite into two pieces. Although the icy moon bears a striking resemblance to the fictional 1977 ‘Death Star’ from the Star Wars film by George Lucas, this low-density satellite probably had a more likely past not as a weapon or space station, but instead as a victim of one catastrophic day in its ancient history. That day Mimas came closer to dying rather than committing any planet-scale homicide.

Saturn currently has 33 known moons. Since Cassini’s launch, 13 new moons have been discovered by ground-based telescopes and two have been found by Cassini itself after the spacecraft enterred Saturn’s orbit.

Mimas has a low density, meaning it probably consists mostly of ice. Because Mimas has such a low temperature of about -200° C (-328°F), the impact features may date back to the time of the moon’s creation. Mimas is named from a mythological Titan who was slain by Hercules. The moon was discovered in 1789 by William Herschel, for whom the huge crater is named after today.

Mimas Dawn, acrylic painting of what an astronaut might see standing on Mimas looking back towards Saturn.
Credit:William K. Hartmann, FIAAA

One prominent gap in the rings of Saturn–in particular the one known as the Cassini division– is caused by Mimas, and a resonance condition set up between Saturn’s dust halo and the orbital period of the tiny moon.

The seven-year outbound journey and four year orbital mission of Cassini-Huygens is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.




The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Office of Space Science, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.