Saturn and Moon Conjunction

[DobDobDob (Ron)]

Hi, I ventured out last night and at about 1.00 am the clouds separated long enough for me to get a good sight of Saturn which was close to the moon. I also saw a satellite around Saturn and today I tried to look up tables using a formula I got out of a book to say which moon it actually was around Saturn, but the math is way beyond me.

I will be asking someone to show me how to calculate these tables when I join the local astronomy club later this month. I was just wondering if anyone else had observed it last night at about the same time (I am west of Sydney, near Blacktown, Parramatta).

If so you might be able to tell me which moon it was and perhaps I can work backwards with these tables.

To me, Saturn appeared slightly elongated at the sides, as you would expect, it appeared that I was looking underneath and off to the side, this made the bottom (from my perspective) visible, but the top was in shadow. I viewed this with 20x80 binoculars and think it looked fantastic. On a better night, I am sure it will be even better.

[erick (Eric)]

Tailwag, it's not clear to me whether you are making out the rings or not. I've been trying to with my 20x80s (yours are better) and my 30x100s and reckon I'm close - I certainly know there are rings there, but I'm trying to clearly see the gap between rings and planet and the shadow on planet/rings. Just need a good night of good seeing in the next weeks.

However, it helps if you know what you are looking for

See this thread for a view of what Saturn should look like as it crosses the meridian

http://www.iceinspace.com.au/forum/s...aturn+meridian

Ignore all my talk of north and south poles - I just didn't know what I was talking about and now I do (Huh! Pull the other one!)

Re moons - forget all the maths - use sky view cafe or something else - it'll give you an illustration of the moon locations at the time you are looking. I've found it great for the four Galilean moons of Jupiter and for Titan, the only moon of Saturn I've spotted so far. Just remember you may have to flip north and south and maybe east and west.

[DobDobDob (Ron)]

Hi erick,

I saw Saturn last night in the same orientation as that photo and your description i.e. the left side higher then the right side. Whilst I was looking intently at the planet I asked myself the exact same question, are those rings or am I viewing a distorted image?

I looked intently at where there should have been a clear indication i.e. the exact point where the oval shape would continue dissecting the elongated 'extra' section.

After awhile I determined the following, despite the clouds I mentioned earlier, when the clouds were not in the way it was quiet clear, so I looked at the planet as a whole or should I say I looked at the image from a point of view of establishing if I was in focus and if the image was crisp and clear. I saw some difference in brightness near the centre of the image where the rings would have been in front of the planet.

Because I believe I was in focus because the curvature of the image was sharp and that I could see differences in brightness within the same image, I concluded that I was in focus and that I had a relatively good view of it.

I then moved over to the side of the planet where the rings would be and studied this area, using averted eyesight as well as direct, after a few minutes my eyes really focused on the exact spot and I believe I saw the rings because there was clearly and 'extra' bit there that was no just a squashed imaged overall.

I can't be sure if I saw the faintest sign of dark between the extra bit and the main body of the image. I doubt that the seeing was good enough for that and I am still too inexperienced to be sure, in a way I doubt myself on several issues as I am a relative beginner.

I can tell you what my gut feeling is however using the bins I have, given a very dark sky with an even better mount (tripod) that I am going to upgrade after just two uses, I believe that with a good half an hour of uninterrupted viewing that the distinction between the rings and the planet will become obvious - I certainly hope so. I hope you can work out what I mean above, I haven't got the right jargon yet, but will get that down pat as we go along.

[acropolite (Phil)]

Eric, at 30x you should be able to differentiate the rings from the planet under clear conditions, I can just make them out with a refractor at 25x.

[DobDobDob (Ron)]

Originally Posted by erick

Re moons - forget all the maths - use sky view cafe or something else - it'll give you an illustration of the moon locations at the time you are looking. I've found it great for the four Galilean moons of Jupiter and for Titan, the only moon of Saturn I've spotted so far. Just remember you may have to flip north and south and maybe east and west.

Just went to this and according to it, there was no moon in the direction I was looking I turned the laptop upside down and Hyperion would have been where I was looking.....but according to me, I was facing North and had the East on my right, at the right time and date and nothing, a real bummer. I suspect that I just don't have the cafe directions right, it almost certainly had to be Hyperion because that was the only one away from the others and off center.

[erick (Eric)]

Originally Posted by acropolite

Eric, at 30x you should be able to differentiate the rings from the planet under clear conditions, I can just make them out with a refractor at 25x.

Yes, I think I'm just waiting for the best conditions and some concentrated viewing at Saturn's maximum elevation. (And for my 30x100s to come back next week - needed repair - the central mounting bar went funny!)

On 11th Feb, when Saturn reaches opposition, it should all become crystal clear - I hope!

[erick (Eric)]

Originally Posted by tailwag

Just went to this and according to it, there was no moon in the direction I was looking I turned the laptop upside down and Hyperion would have been where I was looking.....but according to me, I was facing North and had the East on my right, at the right time and date and nothing, a real bummer. I suspect that I just don't have the cafe directions right, it almost certainly had to be Hyperion because that was the only one away from the others and off center.

Tailwag, start with Jupiter and its moons - however that means getting up at 4am!! Firstly, you'll see better what the disk of a planet looks like at 20x (but I think you've already described Jupiter, as I recall), so what looks different when you look at Saturn has to be the rings (in a simplistic way of thinking). If you cannot make out the rings, it certainly looks like a football compared to everything else!

Secondly, the four moons of Jupiter are easily spotted and then you can orient the image of sky view cafe the right way for our viewing location.

I've only seen Titan when looking at Saturn so far. Not sure whether the other moons of Saturn are particularly visible at 20x???

Now, if I have my brain around it properly, think of us hanging upside down off Earth looking at Saturn. The "top" of Saturn that we see closest to the zenith when Saturn crosses the meridian is therefore its south pole (or close to it depending on relative Earth/Saturn tilts). That is why when you turned the laptop upside down, you got the right view (maybe). So I'm sure now that you definitely have to flip the N/S view.

Next chance I get on Jupiter, I'll work it out again - if Jupiter's moons help and are in a nice recognizable pattern at the time I view.

[DobDobDob (Ron)]

Originally Posted by erick

On 11th Feb, when Saturn reaches opposition, it should all become crystal clear - I hope!

Hi erick, that's only a week away and the all important clouds need to take a holiday, if it is clear, I'll be out there and get my observations and then compare, I might even try to sketch what I see and then attach it - just for a bit of fun, if you do the same we can see if there is any comparison.

In your other posting you said that Saturn was like a football shape, in comparison to Jupiter I totally agree, after having seen them both within a short time (a few days), I can state that to my eye they look completely different in shape and orientation.

Interestingly their sizes were fairly similar, and I really wouldn't like to guess their apparent magnification through binoculars because that seems hard to me. When I look naked eye at different objects, I can appreciate the different magnitudes of the larger stars like Sirius & Canopas, also the familiar Orion constellation stands out and I get a good sense of the magnitude of the different stars in the pattern, then their is the giant moon and of course the Sun.

However when viewed through the binoculars, naturally everything is magnified, so my mental view mag wise is distorted. What is very faint to my naked eye is much larger in the bins. So the question is, if asked to give a relative mag of a star I viewed via binoculars, would I use a mag scale that is somewhat different than as opposed to a mag scale that is naked eye, because they are very different.

What I am trying to say is that when I naked eye viewed either Jupiter or Saturn, they were about a medium size star. let's say I give Sirius a mag of -1 then Saturn would at best been a 1, probably a 2.

This all makes me ask the question of mag (Star Magnitude), does it different from person to person? If say we all use the same star chart that has an accompanying mag scale on it, do we all see the individual star sizes and have the ability to scale then up or down accordingly?

Is this an acquired thing that comes with more experience or is it like learning math tables and simply associating a pre-learned mag size for the most common, larger stars?

I guess I am trying to be 'too-scientific' and explain every single aspect, but I want to know if the size you think an object is, is the same size that I think it is

[erick (Eric)]

tailwag

Just for you, I was going to get out early and check the positions of the moons of Jupiter against the Sky View Cafe illustration - but when I looked out the window at 5am - cloud cover complete!

So I went back to bed for an hour!

But all is not lost - I've taken some back bearings. I saw Titan with Saturn at 11:30pm 10 Jan 2007. Saturn was not far above the horizon (rising) and Titan was seen at about 11:30 o'clock relative to Saturn.

Just rechecking Sky View cafe, I get the right view on the screen if I uncheck the "North on top" box and the "East at left" box. So I'm sure those are the correct settings to give you the views of Jupiter's and Saturn's moons, as we see them.

Happy moon searching, Eric

[DobDobDob (Ron)]

Originally Posted by erick

tailwag

Just for you,

Just rechecking Sky View cafe, I get the right view on the screen if I uncheck the "North on top" box and the "East at left" box. So I'm sure those are the correct settings to give you the views of Jupiter's and Saturn's moons, as we see them.

Thanks for rechecking on Sky View Cafe

I went and took the check marks off North on Top and East on Left, and found three possible candidates, working from nearest the planet outwards were Tethys (III), Rhea (V) and Titan (VI). Remember the Earth's moon was very full at that time and not far away from Saturn, so were the two outer moons washed out because of the lunar brightness, is the inner moon too small to see? I only saw one moon on the night, which of the three could it have been - and why?

Here is another problem, I was in reality facing North and had the East on my right, so why should I uncheck these boxes on the Sky View Cafe program? Is it that it is as a telescope sees it, in reverse?

I would assume that you 'WOULD' check the boxes to coincide with what your true position is, but as you know with the checks on, it does not correspond with what I saw at 1.00am on 4/2/07 from a Western suburb of Sydney. When I take the checks off, it seemingly is correct. Can you explain this?

[erick (Eric)]

OK, it's the "blind" leading the "maybe blind" here! But, the north check box I think I can explain. Remember what I said about us hanging off the bottom of the earth. The uppermost part of Saturn we see in the sky (closest to the zenith) is its south pole.

I think that Sky View Cafe is referring to the north and south poles of Saturn and Jupiter - that's why we have to flip the image to south pole of Saturn at the top of screen or printed page. Probably the same argument applies to the east/west issue - I haven't thought it through. I'm just relying on observation - change the Sky View Cafe illustration until it is what I see through binoculars. Again, the moons of Jupiter are the best to get this right - the four are easily seen and usually in a nice recognisable N/S/E/W layout.

Someone please let me know if I'm still wrong on this and I'll go quiet.

Of course, buy yourself a scope and you'll be upside down/inside out/mirror-imaged!! - I guess I'll work it out when I finally have to!

[erick (Eric)]

Originally Posted by tailwag

...I went and took the check marks off North on Top and East on Left, and found three possible candidates, working from nearest the planet outwards were Tethys (III), Rhea (V) and Titan (VI).... I only saw one moon on the night, which of the three could it have been - and why?

Diameters:

Tethys - 1066km
Rhea - 1529km
Titan - 5151km

Assuming they were all visible and not behind rings or planet, which one would have been most likely? I reckon the biggest - Titan.

[DobDobDob (Ron)]

Originally Posted by erick

OK, it's the "blind" leading the "maybe blind" here! But, the north check box I think I can explain. Remember what I said about us hanging off the bottom of the earth. The uppermost part of Saturn we see in the sky (closest to the zenith) is its south pole.

I think that Sky View Cafe is referring to the north and south poles of Saturn and Jupiter - that's why we have to flip the image to south pole of Saturn at the top of screen or printed page. Probably the same argument applies to the east/west issue - I haven't thought it through. I'm just relying on observation - change the Sky View Cafe illustration until it is what I see through binoculars. Again, the moons of Jupiter are the best to get this right - the four are easily seen and usually in a nice recognisable N/S/E/W layout.

Someone please let me know if I'm still wrong on this and I'll go quiet.

Of course, buy yourself a scope and you'll be upside down/inside out/mirror-imaged!! - I guess I'll work it out when I finally have to!

I see your point, the orientation is of the object not us humans looking at the object, this works for me

[DobDobDob (Ron)]

Originally Posted by erick

Diameters:

Tethys - 1066km
Rhea - 1529km
Titan - 5151km

Assuming they were all visible and not behind rings or planet, which one would have been most likely? I reckon the biggest - Titan.

I concur, I suspect you are correct. I wonder if some of the other binocular boys can confirm whether or not they have ever clearly seen (and this was very clear and very easy to see with 20x80), any of the other two Saturn moons named, or as we suspect they would just be too small for the equipment mentioned.

[erick (Eric)]

Hey tailwag,

See the article by Damian Peach on Jupiter in 2007. Note the illustrations on the first page (also note that the centre and bottom illustrations have been swapped! When you read the caption, this becomes clear.) The main point I wanted to make is his mention that "in all instances north is up".

http://damianpeach.com/images/articl...07/Jupiter.pdf

Eric

[DobDobDob (Ron)]

Originally Posted by erick

Hey tailwag,

See the article by Damian Peach on Jupiter in 2007. Note the illustrations on the first page (also note that the centre and bottom illustrations have been swapped! When you read the caption, this becomes clear.) The main point I wanted to make is his mention that "in all instances north is up".

http://damianpeach.com/images/articl...07/Jupiter.pdf

Eric

Bummer, I just wrote an huge reply to you erick and then went off to check spelling and lost the lot

Okay, so a quick rewrite, I viewed the 3 B&W images facing North and the larger colour image facing South, and using the middle of the 3 B&W images I located the GRS on both, which as you can expect were reversed (top left as opposed to bottom right).

This is fine because the author told me so but what about when I am alone and trying to figure out the cardinal direction of an object?

Here is my underling question, in astronomy generally, notwithstanding the inverse situation of a telescope, do we [A] Refer to the object when we speak of its orientation, [b] ever refer to our own orientation on Earth, [C] is there a standard to be observed.

If as I suspect that most people and software refer to the cardinal direction of the object they are viewing and not themselves, then HOW is the determination made as to what the orientation of that object is, is it [A] taken from the Celestial Equator, [b] Celestial (Southern or Northern) Pole and is it taken using me (the observer) as a third triangulation point?

All I really want to know is - what is the exact formula for working out - when I view a celestial object - whether I am seeing the North of the object, or the South or for that matter, it's East or West as it relates to me.

The second part of the question, assuming the first part is answered and I can understand it, is - does everyone use this, so that when we view an image on this forum or in a book, and assuming we know what it was taken with (assuming a telescope), we can all know what direction the top of the image is.

Sorry to be so long winded, it was better written the first time

[erick (Eric)]

I cannot answer your questions, sorry. Let's hope one of the knowledgeable folks out there jumps in here and explains it all to us in words of one syllable!

However, I was told that when you look at an image published on this forum or in a book, it will be oriented in a way that was most pleasing to the eye - in other words, anyway the author or publisher likes. In short, in space there is no up!

[huckabuck]

hello tailwag,

my guess is Titan @ 8.40 mag. most likely the only of Saturns satelights visible with 20X. the next brightest satelight is Rhea @ 9.80. thats prolly a stretch.

[huckabuck]

also tailwag

it has been my understanding that the east side is the side in the direction an object "appears" to be moving with the naked eye(disregarding telescope and diagonal reversal and flip). as an object appears to slide to the west the leading edge would be the eastern side. ???????

[DobDobDob (Ron)]

Originally Posted by huckabuck

hello tailwag,

my guess is Titan @ 8.40 mag. most likely the only of Saturns satelights visible with 20X. the next brightest satelight is Rhea @ 9.80. thats prolly a stretch.

Yes with Erick's help and using Sky View Cafe, we both figure it to have been Titan, so your input helps put this issue to bed, I am now more than reasonably convinced that I saw Titan that night and as soon as my new heavy duty tripod arrives tomorrow and the clouds go away, I am going to take another very long look at it, armed with my new knowledge as well of course with Sky View Cafe http://www.skyviewcafe.com/skyview.php