Saturn's rings created by collision.When kids learn about the planets, Saturn and its spectacular rings always stand out. And one of the first things First Things is a monthly ecumenical journal concerned with the creation of a "religiously informed public philosophy for the ordering of society" (First Things website). that everyone wants to know is how Saturn got its rings. One theory is that an asteroid or comet hit one of Saturn's icy moons Icy moons are believed to be a common class of planetoids that have a surface mostly of ice, possibly with an ocean under the ice, and possibly including a rocky core of silicate or metallic rocks. The prototype of this class of object is Europa. about 100 million years ago. Upon impact, the moon broke into lots of pieces that spread out into rings. The latest evidence for this theory comes from pictures taken by the Cassini spacecraft, which is currently orbiting Saturn. On July 1, 2004, Cassini flew through the planet's rings on its way into orbit (see "Ringing Saturn"). Looking closely at images taken that day, Cornell University Cornell University, mainly at Ithaca, N.Y.; with land-grant, state, and private support; coeducational; chartered 1865, opened 1868. It was named for Ezra Cornell, who donated $500,000 and a tract of land. With the help of state senator Andrew D. researchers detected four gaps in the bright middle section of Saturn's outermost out·er·most adj. Most distant from the center or inside; outmost. outermost Adjective furthest from the centre or middle Adj. 1. main ring (called the A ring). The gaps are shaped like propellers, and they measure 5 kilometers (3.1 miles) wide. The scientists suspect that the gaps were created by fragments of the shattered shat·ter v. shat·tered, shat·ter·ing, shat·ters v.tr. 1. To cause to break or burst suddenly into pieces, as with a violent blow. 2. a. moon-tiny moonlets about 100 meters (330 feet) across. The moonlets are probably still out there, but they're too small for Cassini to see directly. Scientists had previously detected water-ice chunks in the A ring that measure less than 20 meters (66 feet) across. They had also seen two larger moonlets: Pan, which is 30 kilometers (19 miles) wide, and Daphne, which is 7 kilometers (4 miles) wide. Neither the icy chunks nor the large moonlets, however, can explain the size and shape of the gaps that show up in the Cassini snapshots. The existence of these gaps suggests the presence of fragments of an in-between size. Indeed, it makes sense that a shattered moon would produce moonlets of many sizes. At the same time, the new evidence fails to support another leading theory about Saturn's rings See Saturn. See also: Ring . This theory proposes that the rings formed out of the same gas, dust, and ice that produced the planets during the birth of our solar system solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the most massive part of the solar system, containing almost 99.9% of the system's total mass. . If that were true, however, moonlets would not have been able to get much bigger than about 10 meters (33 feet) across, thanks to Saturn's gravity and collisions between chunks. The Cornell researchers suspect that Saturn's A ring contains some 10 million moonlets that measure about 100 meters wide. http://www.sciencenewsforkids.org/articles/20060405/Note3.asp |
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