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A Question about Saturn's moons

euphony

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euphony

euphony

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Hi guys,

I see in some threads that a few people mention seeing the Cassini division and a couple of saturn's moons. I am yet to see the Cassini division despite pushing up the magnification as far as I possibly can but I expect to get there one day.

In terms of Saturns moons, I was wondering how people can tell if they are seeing them or not? and how they know which ones they are?

When I am viewing Saturn as close as I can, I am able to see some white dots around it at varying distances and locations, but these could quite easily be far off stars that I am seeing.

Any clues as to what to look for at all?

Many thanks

Chris

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Moonshane

Moonshane

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the best thing to do is do a very rough sketch of what you see (literally a child like basic drawing) and then check Stellarium (a free software download) and compare what you drew with what's on Stellarium for your time and location. this helps confirm the moons you saw.

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faulksy

faulksy

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my drawings are child like too.to see the rings you dont always need lots of power, wednesday night i managed 260x mag on saturn that gave good clarity and contrast but at 150x i could still see the cassini division but the planet was smaller

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euphony

euphony

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:)

I can see the rings with my lowest power, but just haven't been able to make out the cassini division yet. Not sure why. maybe I'm not giving myself enough time? The street light behind me may not be helping either.

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euphony

euphony

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when i first viewed saturn, the 3 or 4 moons immediately jumped out at me - they appeared at varying distances but all in a sort of line... is that what you see ? i guess only 3 or 4 will be apparent.

They didn't appear to be in a line as such, they were at slightly different angles. I think I need to spend longer gawping at them next time. There was only around 4 that I noticed though, so it sounds like they may have been what I was glimpsing.

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tjr

tjr

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I would do as Moonshane suggests, make a note of what you're seeing and then check afterwards. Otherwise you can convince yourself that you are seeing them when you're not. Sounds like you have spotted a few though. In my experience they don't always appear where you might expect them to, i.e. not in a straight line like Jupiter's.

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Bat502

Bat502

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the best thing to do is do a very rough sketch of what you see (literally a child like basic drawing) and then check Stellarium (a free software download) and compare what you drew with what's on Stellarium for your time and location. this helps confirm the moons you saw.

Don`t forget to take into consideration that what you draw is probably an upside down version of what you see in Stellarium.

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Fandango

Fandango

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I've used the Saturns Moons link and never yet managed to get them to match! I keep sketching tho. Saturn is my favourite; although I haven't yet seen the Cassini division.

Saturn Question: If Saturn is 2 billion miles away, how come it's so bright when we look at it? Does light continue endlessly in space or is there a limit?

Also despite that brightness the Cassini probe used radiation to power it, apparently because there wasn't enough light to use solar power. That suggests there is a limit yet it shines so brightly which is obviously a reflection of the Sun's light.

Isn't space great!

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tjr

tjr

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Fandango, here is my understanding... Saturn is so bright because it's not very far away (astronomically). Electromagnetic waves will travel indefinitely, but have a max speed (hence the observable universe). If we look further away - and so further back in time - the fabric of space has stretched visible light out into longer wavelengths - no longer visible, but still detectable by other means. I guess this would be the limit of 'light'.

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Andymarrison

Andymarrison

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Wow!! Suddenly it gets a bit deeper! Yes. Sorry about going off topic.

Sorry if I'm going a bit too far "off piste" but I don't seem to be able to private message in response to Fandango's question about light.

The stretching of the wavelength oiSight mentioned above is in fact because the universe is expanding - this means that space time is itself stretching, and light travelling from far away gets "stretched" with it, which changes its colour.

However, even if the universe were not to expand, far away objects would still look much dimmer than close ones. There would be no stretching of wavelength any more, but the energy in the light from a star (or the reflected starlight from a planet) gets spread out over a bigger area the further it has to travel - this is just like the ripples from a pebble thrown into a pond - all of the energy from the splash is at first concentrated in a wave very close to where the pebble hit the water, but as the wave travels outwards the energy gets spread over a larger circular ripple. A leaf on the pond close to the splash would feel a large percentage of the energy from the wave, but the same leaf further out would see a much smaller fraction of the larger ripple, and so would feel much less of the energy of the original splash. It's the same with us looking at the light waves from a star - the closer we are the bigger the fraction of the star's energy that enters our eye (or scope), and the brighter it seems.

In fact the energy per second hitting our eyes here on earth decreases with the square of the distance of the star - if there are two identical stars and one is twice as far away as the other, then the energy per second we see from the nearer one is four times larger (two squared) than what we receive from the farther one.

Light is very interesting stuff (and doesn't always behave like a wave)!

Hope that helps - sorry it's such a long post and apologies for going off topic again. :)

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