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72 votes
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Why can't we see Saturn's phases from earth?

Phases are just different perceived illuminations of an object at different illumination and observing angles. If the observer is, with respect to the object, located in a similar direction as the ...
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55 votes

Why can't we see Saturn's phases from earth?

All the other answers here are complete, and more in-depth than anything I would write. However, if you prefer to look at things visually, here is a terrible not-to-scale 2 minute paint drawing. No ...
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45 votes
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How large can a ball of water be without fusion starting?

You really need a full-blown stellar evolution model to answer this precisely and I'm not sure anyone would ever have done this with an oxygen-dominated star. To zeroth order the answer will be the ...
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44 votes

Why is there a mountain inside the Herschel crater on Mimas?

In the extreme energy of a large impact, the rock behaves like a liquid (It isn't actually completely melted, though some is. The extreme forces cause the rock to flow). As the impactor hits the moon, ...
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31 votes
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How is it possible that Saturn's gravitational acceleration felt by Mimas is stronger than Mimas' own surface gravity?

An object on Mimas' surface would be much more attracted to Saturn than it is to Mimas. You are missing that Mimas as a whole accelerates gravitationally toward Saturn. What this means is that a ...
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30 votes

Help understanding this unsettling image of Titan, Epimetheus, and Saturn's rings?

This NASA page says this photo was taken on April 28 2006. Using Celestia, I managed to find the picture from Cassini that best lines up with the photo. It doesn't match up precisely, but that's to ...
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24 votes
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How did Arecibo detect methane lakes on Titan, and image Saturn's rings?

Titan "lakes": Published Open Access in Science: Radar Evidence for Liquid Surfaces on Titan Campbell, D. B., Black, G. J., Carter, L. M., and Ostro, S. J., Science 302, 5644, pp. 431-434, 17 Oct ...
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23 votes
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Which Saturn satellite passes closest to Saturn's rings and at what distance?

Pan, Daphnis, and various other moonlets, I would argue, are inside the rings. If you explicitly discount the Encke gap (which Pan orbits in) and the Keeler gap (which Daphnis orbits in) as being ...
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17 votes
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Are there other pictures of Titan surface from Huygens?

One second of googling reveals the whole archive: http://esamultimedia.esa.int/docs/titanraw/index.htm (note you can click onto the strips to inspect them!) The archive depicts the whole decent of ...
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16 votes

Planets looks like normal stars when I see them using telescope

I'm a VERY amateur observer myself and my telescope has the exact same aperture as yours. I can all but guarantee that you should definitely be able to see Saturn rings and Jupiter moons (and even ...
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14 votes
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"If earth had rings like Saturn": A few further thoughts on the consequences

This is a big one, so I'll split it into parts based on the questions you asked: 1) Earth has roughly a distance of 1 AU to the sun, Saturn between 9 and 10. Sun's gravity would therefore have a ...
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14 votes

Hypothetically, would we be able to see the moon from Saturn's North Pole?

First of all, at that distance seeing the Moon and seeing the Earth amounts to the same thing. At its closest, Saturn is around 3000 times as far from Earth as the Moon is, so viewed from Saturn, the ...
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13 votes
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Why is Enceladus's albedo greater than 1?

To answer this, one really has to understand how the geometric and bond albedos are defined. Let's start with the bond albedo since its simpler. Bond Albedo The Bond Albedo is just the fraction of ...
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13 votes
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Help understanding this unsettling image of Titan, Epimetheus, and Saturn's rings?

The JPL Solar System Simulator doesn't show Epimetheus but does show Titan behind the Encke gap at 2006-04-28 08:12 UTC. The simulated surface texture is probably composed of VIMS images in infrared ...
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13 votes
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What is this 877-year cycle in the orbits of Jupiter & Saturn, and this multimillion-year cycle in the lunar orbit?

A biography of Laplace mentions his derivation of an 877 year cycle in the motions of Saturn and Jupiter. The periods of the planets are about 30 and 12 years respectively so they will approximately ...
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13 votes

Planets looks like normal stars when I see them using telescope

With f=900 mm and a 25 and 10 mm eyepieces you would be viewing at 36x and 72x. 36x is a very reasonable magnification under any condition, and 72x can probably still be considered "useful ...
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12 votes
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Hypothetically, would we be able to see the moon from Saturn's North Pole?

Yes, if you observe Earth and the Moon at a favorable time. Near a Saturn summer solstice, e.g. between 2012 and 2022, Earth appears well above the horizon from Saturn's north pole. If the planet body ...
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12 votes

How did Arecibo detect methane lakes on Titan, and image Saturn's rings?

It did not detect methane lakes. It found that Titan was shiny (in radar terms): that is, the reflections were from a smooth surface rather than a rough one, and at the same time not very intense. ...
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11 votes
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How long do planetary rings last?

It appears (and I am no expert) that Saturn's ring evolution is governed mainly by "viscous spreading" - collisions between ring particles; and also by interactions with Saturn's moons (resonances); ...
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11 votes

Will Saturn's rings become a moon?

The currently leading answer is correct to say that moon formation inside the Roche limit is unlikely. However, the disk is evolving due to viscosity between the particles, and as a consequence it "...
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11 votes
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What are the periods of Saturn's rings?

Hours to days. The orbital period is proportional to the 3/2 power of the orbital radius, and the orbital period of the moon Methone (and thus of the particles in its associated ring arc) is very ...
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11 votes

Why can't we see Saturn's phases from earth?

The answer is simple geometry: we are 1 AU from the Sun, Saturn is 10x further from the Sun. Looked at Earth from Saturn, Earth is always in front, behind or immediately next to the sun; an observer ...
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11 votes
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Are the Jupiter-Saturn conjunctions and winter solstice related?

Not in any way, no. The December solstice is the moment when the Sun reaches its southernmost point in its daily path in the sky (the June solstice, when the Sun reaches its northernmost point). It ...
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10 votes
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How is a day measured on a gas giant?

That the rotation period of the bulk mass of a planet is estimated through something with the magnetic field is true. But let me maybe elaborate a bit in-depth on that. No planetary magnetic field ...
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10 votes
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Size of Saturn's ring material

The vast majority of the particles in Saturn's rings are small, on the order of $\sim10^{-1}$ m or lower. The columnar number density, according to data from Voyager 1 and Earth-based observations, ...
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10 votes

How to measure mass of planets' core from orbit

I certainly don't know the details of these kinds of calculations, but as my thought is a bit too long for a comment I'll write it up as an answer. If you measure the flattening of a planet due to ...
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9 votes

Trying to understand the way Saturn's ring look in this famous Cassini image

What's going on with the distortion of the rings on the upper half when they (presumably) cross in front of Saturn? The brownish areas you see on Saturn are ring light, analogous to seeing the Earth ...
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9 votes
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Why are Saturn bands much fainter than Jupiter's?

I'll give this one a shot. Correction is welcome. Upper atmosphere temperature. It's not just elements that give a planet color, but the temperature of elements. When we examine what a planet ...
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9 votes
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Is there, in fact, any close-up photography of Saturn's rings, showing individual pebbles/rocks?

The rings are about 3% solid in the densest parts, but this translates to a separation between 30cm particles of about 1metre. There are no images Because approaching the dense part of the rings would ...
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9 votes

Hypothetically, would we be able to see the moon from Saturn's North Pole?

For these kind of questions, you might want to use Stellarium, a free open source planetarium. You can specify the location of the observer on many celestial bodies, including Saturn. Any time ...
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