Реферат: Saturn
Much like its neighbor Jupiter, the sixth planet from the sun has a rockycore and a gaseous surface. But Saturn is chiefly known for its intricateseries of rings that encircle it. The mile-thick rings are made of countlessorbiting ice particles, from less than an inch to several feet in size.
Up close, it's clear that Saturn has more rings than we can count.But though you can't see all of them from Earth, you can spot three of them witha good telescope,.
The two outermost rings are separated by a dark band called the CassiniDivision, named for the astronomer who discovered it in 1675. The Cassinidivision isn't empty, but it has less material in it. The middle ring is thebrightest, and just inside it is a fuzzy one that can be difficult to spot.
Saturn has 18 known satellites, made mostly of ice and rock. The largest,Titan, orbits Saturn every 16 days and is visible through a good-sized amateurtelescope. Titan, which is larger than the planet Mercury, has a thickatmosphere that obscures its surface. Though researchers aren't sure how manymoons Saturn has, the total is likely at least 20, and may be much higher.
Historical notes
When Galileo Galilei first studied Saturn in the early 1600s, he thoughtit was an object with three parts. Not knowing he was seeing a planet withrings, the stumped astronomer entered a small drawing — a symbol with onelarge circle and two smaller ones — in his notebook, as a noun in a sentencedescribing his discovery. Debate raged for more than 40 years about these«ears,» until Christiaan Huygens proposed that they were rings.Giovanni Domenico Cassini later discovered a gap between the rings, whichgained his name, and he also proposed that the rings were not solid objects,but rather made of small particles.
Список литературы
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