The Dion ice satellite is floating against the backdrop of a giant parent planet in this new image, taken by NASA's Cassini spacecraft.
This photograph, which Cassini took on May 21, shows the satellite of Dion crossing the Saturn disk. “A careful study of such“ transits ”can help astronomers better understand the orbit of Dione and other satellites in the solar system,” said NASA officials.
In addition, NASA’s Kepler Space Telescope uses a similar tool to search for exoplanets, looking out for them in the tiny dips of star brightness during the transit of alien worlds. The study of light coming from such extrasolar systems can also reveal details about the composition of the atmospheres of these exoplanets.
Having 696 miles (1120 km) in diameter, Dion is the fourth largest of more than sixty Saturn's satellites. Only Titan, Ray and Japet are larger than her. One part of Dione is highly craterized, and the other side has mysterious ice cliffs and rifts, which are stretched for dozens and even hundreds of kilometers. Cassini also discovered the thin oxygen atmosphere surrounding the cold satellite. Cassini took this photograph from about 1, 4 million miles (2, 3 million km) from Saturn. Image resolution is 9 miles (14 km) per pixel.
But the spacecraft also made closer flights to Dione throughout its multi-year program. During the last flight, which occurred on August 17, Cassini passed just 295 miles (474 km) from the surface of the satellite, making amazing images.
However, the span of August 17 will be the last closest flight over this icy satellite. In September 2017, Cassini will be intentionally immersed in the thick atmosphere of Saturn in September 2017.
The Cassini mission, worth $ 3,2 billion, which was launched in 1997 and arrived on the Saturn system in 2004, is a joint program of NASA, the European Space Agency and the Italian Space Agency.