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PLANETARY RING SYSTEM IN [#9 EMANATIONS] |
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In early 2371, in [#9 Emanations], the crew of USS Voyager make a landmark discovery in the spectacular ring system of a Class-D planet: a new transuranic element, atomic number 247 (there are 246 elements known to Federation science). Even more remarkably, element 247 appears to be a decay product of deceased humanoid bodies discovered in the larger planetoids that comprise the ring system. (However, it turns out that the element detected by Voyager's scanners is emanating from the deceased bodies of members of the Vhnori species. As the bodies' tissues decay, the cell membrane breaks down into a bio-polymer resin which is then excreted by the epidermal layer, and it is this which the crew thought was a new element with an unusually large atomic mass, containing over 550 nucleons.)
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| USS Voyager and the planetary ring system, [#9 Emanations] |
The ringed Saturn-like planet which Voyager's crew encounter in 2371 in [#9 Emanations] is described as a Class-D world, but that is a blooper as the term had previously been established in Star Trek to describe asteroids, and [DS9: Starship Down] further established Saturn to be a Class-J planet. Bormanis says that Class-J was established as being the designation for jovian planets which are also known as "gas giants". Therefore, it is suggested, in order to get round the blooper, that the Voyager crew actually refer to the asteroid-like objects in the planet's rings, or maybe they are just overly excited at the discovery of element 247.
Saturn, photographed by the Hubble Space Telescope |
All of the jovian planets in our solar system have rings. (Jovian planets are large, mostly gaseous planets.) The rings of Saturn are the brightest and best known planetary ring system. Saturn was a great puzzle to Galileo, the first
person to point a telescope at the planet in the year 1610. In Galileo's relatively crude instrument, Saturn's rings looked like
a pair of ears or bumps on either side of a larger disk. A few
years later Galileo noted that these "bumps" had disappeared. |
As telescopes improved, they provided sharper views of the
planets. In 1659, Christian Huygens announced that he was
able to resolve the "bumps" observed by Galileo into a flat disk
structure ringing the entire planet. The occasional disappearance of the rings was explained by the fact that every fifteen
years or so the rings are tilted "edge on" toward the Earth, making it impossible to see them even in large telescopes (the most
recent "ring plane crossing" occurred in August 1996). This in
turn suggests that the rings of Saturn are very thin relative to
their diameter; in fact, if you were to build a scale model of
Saturn, making the rings only as thick as a piece of typing paper
(about 0.1 milimetres), the diameter of the ring system would
be about forty metres.
The nineteenth-century physicist James Clerk Maxwell
argued that the rings of Saturn are not solid, but consist of
uncountable millions of smaller particles orbiting Saturn in
much the same way as our Moon orbits the Earth. Maxwell's
theory was confirmed in 1895 when spectroscopic analysis
revealed that the inner edge of the Saturn ring system revolved
faster than the outer edge, which would be impossible if the
rings were a single, solid object. The American Pioneer and
Voyager spacecraft have revealed the rings of Saturn to be composed of icy particles ranging in size from a fraction of a millimeter to twenty or thirty metres across.
Jupiter, photographed by the Hubble Space Telescope
Neptune, photographed by the Hubble Space Telescope
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Jupiter, Uranus, and Neptune also possess thin rings of icy and rocky material. These rings systems are not nearly as
extensive as the rings of Saturn and are practically invisible to
ground-based telescopes. The rings of Uranus were discovered
through a phenomenon called occultation. An occultation
occurs whenever one astronomical body passes in front of
another. Astronomers observing Uranus in 1976 noticed that a
bright star passing behind Uranus "flickered" before it was
blocked by the disk of the planet. The flickering pattern was
repeated exactly as the star emerged on the other side of
Uranus's disk, which ruled out the possibility that the flickering
was nothing more than twinkling caused by turbulence in
Earth's atmosphere. The astronomers concluded that Uranus is
encircled by several thin rings.
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Jovian planets: Jupiter, Saturn, Uranus and Neptune
Planetary rings are probably created when a small moon
collides with another moon, or ventures so close to its planet
that gravitational tidal forces shred it apart. The resulting fragments spread out into concentric orbits, breaking into ever
smaller fragments through repeated collisions, eventually
forming a set of rings. Ring systems are thought to be a somewhat transient phenomena, lasting perhaps several hundred
million years. Rings as magnificent as the rings of Saturn are probably rare. We are truly privileged to live in our solar system
at a time when this extraordinary planetary spectacle is readily
visible in backyard telescopes. If you've never seen Saturn in a
telescope, I urge you to visit a planetarium or local astronomy
club and take a look. You'll never forget it. Seeing the rings of Saturn in her brother's telescope when she was young was what made Rain Robinson become an astronomer, as told to Tom Paris in [#51 Future's End, Part Two].
See also the entry: Gas giant in [#97 Extreme Risk].
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