how old a saturns rings

I believe that I heard once that the rings of saturn are only about 50
millions years old

( so if dino's had telescopes they would not see any rings )

I cant remember where I read that ( web probably )

anyways, this has been bugging me.

can anyone, confirm or blast this statement?

( if true, how did we figure this out? )

thanks
Carl

http://science.nasa.gov/headlines/y2002/12feb_rings.htm

ah, I found the 'answer' here


"carl" wrote in message
.. .
I believe that I heard once that the rings of saturn are only about 50
millions years old

( so if dino's had telescopes they would not see any rings )

I cant remember where I read that ( web probably )

anyways, this has been bugging me.

can anyone, confirm or blast this statement?

( if true, how did we figure this out? )

thanks
Carl

Hi Carl One could have a theory that Saturns rings are older than the
solar system. Bert

BenignVanilla wrote:

I guess some of the material could be extra-solar material having been
caught by Saturn's gravity, but surely...the rings are no older then the
solar system as they orbit an object in the solar system. They can't be
older then the thing they orbit.

In fact they're believed to be much younger than the planet; their
bright appearance suggests they haven't been around long enough to
get 'dirty'.

--Odysseus

In message , Odysseus
writes
BenignVanilla wrote:

I guess some of the material could be extra-solar material having been
caught by Saturn's gravity, but surely...the rings are no older then the
solar system as they orbit an object in the solar system. They can't be
older then the thing they orbit.

In fact they're believed to be much younger than the planet; their
bright appearance suggests they haven't been around long enough to
get 'dirty'.

After a while you begin to wonder how we are so "lucky".
We are around at just the right time to see Neptune's moon Triton, which
is due to become another ring system in 10 to 100 million years.
We are seeing Saturn's rings, and according to one theory they are only
3 million years old.
We are seeing total eclipses of the Moon, which probably gave a huge
boost to ancient astronomy and religion.
Does anyone still think that Phobos is going to crash into Mars in the
same sort of 100 million year frame, or has that idea been discounted?
So are exciting things always happening in the solar system, or is the
current era special?
--
"Roads in space for rockets to travel....four-dimensional roads, curving with
relativity"
Mail to jsilverlight AT merseia.fsnet.co.uk is welcome.
Or visit Jonathan's Space Site http://www.merseia.fsnet.co.uk

The best theory how Saturn rings got there is A comet past to close. It
went into orbit. The reason this theory makes for good thinking is the
material the rings are made of,and I don't see comets as a solid object.
I see them as a clump of rocks,ice,ammonia,and solid CO2.
However I don't think all comets are the same. Bert PS
the tail is made of CO2 gas,and ammonia

Bert posted:

The best theory how Saturn rings got there is A comet past to close.


That is a lousy theory for a number of reasons. First, the ring material is
in a nice circular orbit which is nearly impossible to achieve for the capture
of a fast moving body like a comet. Second, the total mass of the rings is
about 3.4 x 10^19 kilograms, which is many times the mass of even a large
comet and is compariable to the mass of Saturn's moon Mimas or several other
small Saturnian moons. The best theories are 1: that the rings formed from
material which condensed close to Saturn but so close that the planet's tidal
forces kept it from forming a single large body, or 2: that a small moon's
orbit decayed just enough to let it pass inside Saturn's Roche limit, causing
tidal forces to pull it apart. The characterisics of the material in the
rings is similar to that of Saturn's inner moons (ice and rock. In addition
several tiny moons orbit close to or just within the ring system (Pan orbits
inside the Encke Division of the A-ring), and this supports the idea that the
rings were formed from material which was already there.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 10th Annual NEBRASKA STAR PARTY *
* July 27-Aug. 1st, 2003, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
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David we don't know how long the rings have been there(yes?) and time
can make orbits more circular. This material can't be to large,or
heavy,and that would make a more circular ring over time. We don't know
how fast the comet was going??? It could have come in just the right
angle,and relative motion,and that would help my theory. Do the rings
rotate in the same direction relative to Saturn"s rotation. Since there
are more than one ring that helps my theory. The big edge I have is the
sizes and the material that makes up the rings structure
Bert

Bert posted:

time can make orbits more circular.

No, "time" does not necessarily make orbits more circular. Look at Mercury.
It has been there for probably 4 billion years or so, yet it has the second
most eccentric orbit of all the planets in the solar system. To make an orbit
circular requires an interaction with either some other body or the presence
of atmospheric drag. The rings of Saturn are far above the atmosphere of
Saturn, and all the other bodies near the rings are in nearly circular orbits
(and are quite small). The two theories I mentioned are the best ones
currently available.

This material can't be to large,or
heavy,and that would make a more circular ring over time.


No, again, the size of the material does not necessarily make an orbit more
circular. Some small asteroids are in wildy eccentric orbits and have been so
for millions, if not billions of years. The ring material is thought to be
mostly in the 1 centimeter to 5 meter size range with a few larger chunks
mixed in (like Pan, which is around 20 kilometers across).

We don't know how fast the comet was going???

Most comets pass the planets at speeds well in excess of the planet's escape
velocity, therefore they either miss the planet with only a small change in
their orbital shape, or they hit the planet. They don't usually go into orbit
(and certainly not a nearly circular one which is in perfect alignment with
the equator of Saturn). Again, the masses of comets are far less than the
total mass of the ring system of Saturn, so comets are unlikely sources of
ring material.

Do the rings
rotate in the same direction relative to Saturn"s rotation

Yes, they do. In fact, the plane of the rings is nearly same as the plane of
Saturn's equator, which makes it far more likely that they were formed from
the material cloud which eventually formed Saturn and its moons.

Since there
are more than one ring that helps my theory.

No, it does not. The apparent "gaps" in the rings are caused by perturbations
from nearby moons or from the presence of small moons orbiting within the
rings themselves. Examples include the Encke Division, which is due to the
presence of the tiny moon Pan, and the Cassini Division, which is due mostly
to the gravitational tugs and pulls of some of the more massive moons like
Titan which removes some material from these regions due to an orbital
"resonance" they have. However, even some of these gaps have material within
them (the Cassini Division is full of fine debris).

--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 10th Annual NEBRASKA STAR PARTY *
* July 27-Aug. 1st, 2003, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************