Nasa's Cassini probe reveals clouds created by impact of speeding meteroids crashing into Saturn's rings Nasa spacecraft observed impact of small meteoroids on Saturn's rings Small meteoroids break into streams of rubble that crash into rings Cassini probe images reveal how objects create clouds upon impact Saturnian equinox in summer 2009 provided ideal observation conditions Shallow angle of sun on rings acting as an 'anti-cloaking device' Clouds of debris appeared bright against the darkened rings of Saturn Images beamed back from Nasa's Cassini spacecraft have revealed meteors smashing into Saturn's rings for the first time. They make Saturn's rings the only location besides the Earth, the moon and Jupiter where scientists have been able to observe impacts as they occur. Measuring from one centimetre to several metres across, the objects break into streams of rubble as they 'pummel' the planet before kicking up clouds of debris, Nasa scientists said. Saturn's rings: The arrows indicate the clouds kicked up by the impact of the meteors. Measuring from one centimetre to several metres across, the objects break into streams of rubble as they 'pummel' the planet before kicking up clouds of debris, Nasa scientists said Scientists believe the meteoroids break up into streams of rubble upon hitting Saturn's rings, creating smaller, slower pieces that enter into orbit around the planet. The impact of these secondary meteoroid bits kicks up the clouds, which are quickly pulled into bright, diagonal streaks. Studying the impact rate of meteoroids from outside the Saturnian system helps its scientists to understand how different planet systems in our solar system formed, Nasa said. The solar system is full of small, speeding objects which frequently pummel planetary bodies. It took scientists years to distinguish the tracks left by nine meteoroids in 2005, 2009 and 2012. Results from Cassini have already shown Saturn's rings act as effective detectors of many kinds of surrounding phenomena, including the interior structure of the planet and the orbits of its moons. For example, a subtle but extensive corrugation that ripples 12,000 miles across the innermost rings tells of a very large meteoroid impact in 1983. Impact: Saturn's rings are bombarded with small, speeding meteroids that break upon impact and enter into orbit around the planet Shearing: This illustration shows how the cloud of debris is initially circular, but then shears as a result of the particles in the cloud having differing orbital speeds around Saturn Speeding: The meteoroids Cassini detected crashing into Saturn's rings are comparable in size to this one pictured hurtling over Russia in February 'These new results imply the current-day impact rates for small particles at Saturn are about the same as those at Earth - two very different neighborhoods in our solar system - and this is exciting to see,' said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. 'It took Saturn's rings acting like a giant meteoroid detector - 100 times the surface area of the Earth - and Cassini's long-term tour of the Saturn system to address this question.' Conditions were especially good for viewing the debris left by meteoroid impacts during the Saturnian equinox in the summer of 2009, when the very shallow sun angle on the rings caused the clouds of debris to look bright against the darkened rings in pictures from Cassini's imaging science subsystem. Saturn lies 890 million miles from the Sun on average. It has a diameter of 74,897 miles. It's an extremely cold planet, with an average temperature of -140C (-220F). Saturn is made of liquid and solid hydrogen and helium and is so light it would float on water. It's most famous for its rings, which were first discovered in the 17th-century. They extend 46,000 miles out and have a total diameter of almost 170,000 miles. It has 60 moons - more than any other planet in the solar system, bar Jupiter. One of them, Titan, is the second largest in the solar system and actually has an atmosphere - composed mainly of nitrogen. Saturn is extremely stormy, with winds gusting at 1,000mph at the equator. 'We knew these little impacts were constantly occurring, but we didn't know how big or how frequent they might be, and we didn't necessarily expect them to take the form of spectacular shearing clouds,' said Matt Tiscareno, lead author of the paper and a Cassini participating scientist at Cornell University in Ithaca, New York. The sunlight shining edge-on to the rings at the Saturnian equinox acted like an anti-cloaking device, so these usually invisible features became plain to see. Mr Tiscareno and his colleagues now suspect meteoroids of this size break up on a first encounter with the rings, creating secondary meteoroids that then enter into orbit around Saturn. The impact into the rings of these bits kicks up the clouds. The tiny particles forming these clouds have a range of orbital speeds around Saturn, and the clouds they form soon are pulled into bright, extended streaks. 'Saturn's rings are unusually bright and clean, leading some to suggest that the rings are actually much younger than Saturn,' said Jeff Cuzzi, a co-author of the paper and a Cassini interdisciplinary scientist specializing in planetary rings and dust at NASA's Ames Research Center in Moffett Field, California. To assess this dramatic claim, we must know more about the rate at which outside material is bombarding the rings. This latest analysis helps fill in that story with detection of impactors of a size that we weren't previously able to detect directly.' Long tour: An artist's impression of the Cassini probe, which is exploring the Saturn system, nearing the planet's rings The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, Pasadena, California, a division of the California Institute of Technology, Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate in Washington. JPL designed, developed and assembled the Cassini orbiter and its two onboard cameras. The imaging team consists of scientists from the United States, England, France and Germany. The imaging operations center is based at the Space Science Institute in Boulder, Colorado. Details of the observations appear in a paper in the latest edition of Science.