Atlas is the tiny grey speck just above Saturn’s outermost ring

(Mirror Daily, United States) – NASA’s Cassini spacecraft returned with an image of three Saturn moons with one hidden within the gas giant’s rings. It may be hard to spot, but the third of the planet’s natural satellites is there, tucked between its rings.

The image was captured by Cassini during its fly-by of Saturn’s icy moon, Enceladus on December 19th of last year. At the time when the picture was taken, the orbiter was around 1.3 million miles away from Saturn’s moon. It managed to capture three of the planet’s moons, yet only two of them appear visible.

Featured in the image is, naturally, Enceladus, seen above the rings. It’s approximately 313 miles across (or 504 km) and has been deemed as one of the more interesting moons of Saturn. It has become famous across the world for potentially hiding a subsurface ocean. In fact, NASA is planning a lander within the next couple of years that will dig deep beyond its outer layer.

The big standout of the image, however, is Rhea. The giant moon stands at 949 miles across (or 1,527 km) and is featured below the ring. When the picture was taken, Cassini was approximately 1.8 million miles away from the huge moon. It displays the grandeur of Rhea, in spite of its dull-looking aspect.

However, that’s only two of the three. The third, Atlas is also captured in the picture. In spite of the fact that Cassini was further away from Rhea, Atlas appears to be much smaller in its minute size of just 19 miles across (or 30 km). It’s certainly there upon closer inspection. An easy way to find it is to look just above the thin line that shows Saturn’s outermost ring, the F ring. It’s a 2 pixels wide grey speck against the pitch black, somewhere to the left of Rhea and near the center of the image.

That little grey dot is Saturn’s moon.

In spite of its size, Atlas does arrive with an interesting feature. It displays a beautifully and geologically interesting equatorial ridge, like a giant seam across its mid-section. While it might not seem special, it’s certainly not a common characteristic. In fact, it’s a trait only apparent on Saturn’s moons, specifically just three out of the sixty-two confirmed.

Only Atlas, Pan, and Iapetus have become known to have the odd ridge.

Scientists believed it has formed due to the dust particles accumulated by exposure to Saturn’s rings, where it’s full of dust, rock, and ice. However, it’s only an estimation. The true formation of the ridges remains a mystery, as Iapetus has not been exposed to the particles in Saturn’s ring, and yet it displays the same feature. Perhaps it’s some other process altogether.

Image source: phys.org