Translated material
Sixtieth moon of the sixth planet
Scientists have found a new satellite of Saturn
Astronomers studying images taken by the Cassini interplanetary station have discovered a satellite of Saturn under the code number S/2007 S4. In everyday life they called him Frank, but this is not yet an official name, but rather a “nickname” for internal correspondence. There is nothing special about this celestial body: a very small rock of irregular shape, consisting of ice and frozen stones with a diameter of about two kilometers. For the scale of Saturn, this is just a baby; even on Earth in the Southern Ocean, icebergs of much larger sizes are often found. However, it was Frank who turned out to be the 60th known satellite of Saturn.The orbit of S/2007 S4 is located between two other Saturn moons - Metone and Pallene, which were discovered some time ago by the same group of astronomers. Frank was first found in a photograph on May 30 of this year, but to make sure that it was really a satellite, they had to pull up old photographs from Cassini, taken back in 2004. After this, it was possible to approximately calculate the orbit of S/2007 S4. This won’t hurt: after all, both Cassini and other interplanetary automatic stations will still fly and fly here, and it’s better to know in advance where you can stumble upon a rock. However, earthlings’ spacecraft fly so close to Saturn quite rarely.
Saturn, even without the newly discovered Frank, had one of the largest satellite armadas in the Solar System (Jupiter now has 63 moons, Uranus has 27, Neptune has only 13). The variety of debris of various shapes flying around the sixth planet is amazing. The largest of them, Titan with a diameter of 5150 km, is much larger than our Moon and, unlike it, even has its own dense atmosphere. The rest are smaller: for example, Saturn's second largest moon Iapetus (diameter 1436 km) is just a very large ice ball without any atmosphere and with classic craters - traces of cosmic collisions.
The first moons of Saturn were discovered back in the era of the first telescopes: for example, Titan was examined in 1655 by the famous Dutchman Christian Huygens. In the 70-80s of the same century, the Italian Giovanni Cassini discovered four more large satellites in the vicinity of the planet - Iapetus, Rhea, Tethys and Dione, and in 1789 William Herschel found Mimas and Enceladus. In the 19th century, the number of Saturn's moons reached nine: Hyperion was discovered in 1848 (has no relation to the planet from Dan Simmons' science fiction novels), and Phoebe in 1898. The last ones from Earth managed to spot Janus - this irregularly shaped rock, measuring no more than 200 km, was discovered already in 1966.
After this, the number of satellites of Saturn known to mankind began to be determined only by the power of the instruments installed at interplanetary stations and the attentiveness of scientists examining the resulting images. Apparently, in the vicinity of the giant planet, in addition to large satellites like Titan or Iapetus and fine dust collected in the famous rings, there are several hundred or thousand more fragments flying in size from several meters to several tens of kilometers. And the more detailed the images obtained by astronomers, the longer the list of the Saturn family becomes.
In 1980-1981, the American interplanetary spacecraft Voyager 1 and Voyager 2 flew past Saturn. With their help, it was possible to discover several more satellites, the dimensions of which are several tens of kilometers. Then scientists had to wait until the 2000s, when they began to discover groups of very small “pebbles” several kilometers in size. At this time, the planet, named after the ancient Roman god Saturn, had moons with names from Eskimo, Scandinavian and Celtic mythology, such as Kiviok, Skadi or Albiorix. And when the Cassini spacecraft reached the planet in 2004, the list of celestial bodies orbiting the hydrogen giant began to grow so quickly that astronomers no longer had time to come up with names for them. Now only four dozen of the 60 known satellites have received official proper names.
Most of the satellites discovered in recent years are small pieces of ice and irregularly shaped rocks. Their size, as a rule, does not exceed four to six kilometers. Even in large-scale photographs they appear as pale, barely visible dots. S/2007 S4 is just an example of such a microsatellite, and it is certainly not the last one discovered by astronomers in images from Cassini. This year alone it is already the fourth - in April and May, three more equally small celestial bodies were identified.
Nevertheless, Frank is still a special, anniversary moon. True, such anniversaries in the case of Saturn are happening more and more often. It took as many as 311 years to discover ten satellites, two dozen were reached in another 24 years, and the third ten were taken in less than a year. And only a little more than a year passed from the fifty-century mark to Frank - in the spring-summer of 2006, nine new Saturn moons were discovered in photographs.