Jupiter Last Night

[JohnKA]

Out with my son last night in the garden, looking at Jupiter, amazing !

Had to 'find' it first with a 32mm Plossl and then tried my other eyepieces.

With the 32mm it was crystal sharp but using the 6mm, 10mm and 15mm it was very difficult to get a good focus, which was a tad dissappointing.

What would cause this ?

[arad85]

Pushing the mag too high for the conditions or collimation off. What 'scope have you got?

[ashenlight]

Hello John great that you found Jupiter last night, I think I know what may be causing your problem as I have experienced what you describe before.

How well you can see objects through telescopes depends on the 'seeing.' This refers to how steady the atmosphere is - their can be 'turbulence' which can upset your image as different levels of air move in different directions causing everything to seem blurry and out of focus. Occasionally, the currents of air all move in the same direction - this is perfect seeing and if you experience this, you'll get fleeting seconds of the most clear views of Jupiter and other objects you are looking at at the time. Seeing differs from location to location, so whilst someone in one place will report good seeing, the person in another location just won't have much luck at all. Tbh, alot of it is down to luck!

As you step up the magnification on an object, as you did moving from a 32mm EP right down to a 6mm EP, you are effectively magnifying the atmosphere too, - at the mag the 32mm EP gives you, the atmosphere wasn't causing you any problems, but once the mag got high enough, you are magnifying all the choppy air currents which affect the image you can see. This is why you couldn't get focus.

It's with this in mind that we should tailor our choice of eyepieces to the conditions on a particular night. DOn't be disheartened if you can't get good focus at high mag one night - enjoy the view of the planet and its moons through a lower mag EP, giving you a larger field of view. Also, stay at the EP for as long as you can - the seeing will improve as the 'turbulence' settles down, giving you those fleeting moments of great conditions I mentioned earlier.

Here's some graphics of Jupiter under bad -> good seeing conditions, to help you get to grips with it Simulated Seeing Animations

Here's an article on the atmosphere and observing, which helped me understand seeing alot when I started out The Atmosphere and Observing - A guide to Astronomical seeing. - How To

I hope this helps you, some people may come forward with different explanations, but I suspect it is the atmosphere that is causing you problems! DOn't forget that Jupiter is still fairly low down for us in the UK - things lower to the horizon are affected more by atmospheric conditions as you have to look through more of the Earth's atmosphere to observe them. Also be aware that buildings and even the ground can give off heat throughout the night that has been collected throughout the day, this can make the air appear to 'boil' above them when viewed through a scope, so affecting your views.

Another possibility is collimation, I hope someone will come forward with some advice about that, as it isn't really my forte. All the best

[JohnKA]

Pushing the mag too high for the conditions or collimation off. What 'scope have you got?

Its a Celestron Astromaster 90AZ, Realise its entry level kit, but the view from the 32mm was brilliant !

[kniclander]

seeing was pretty good last night - I saw a very clear shadow transit of jupiter in my ed80 at x90 (unless someone comes forward and tells me there wasn't a shadow transit last night....)

remember, at higher mags, focussing must be much more precise than at lower mags and it can e quite difficult to find the "sweet spot"

hth.

[John]

seeing was pretty good last night - I saw a very clear shadow transit of jupiter in my ed80 at x90 (unless someone comes forward and tells me there wasn't a shadow transit last night....)

There was a shadow transit last night - I saw it with my 5" refractor

Havn't had time to work out which moon it was yet though .....

John,

While the 6mm eyepiece was probably too much power I would have thought that the 15mm and 10mm eyepieces would have shown a decent image ?.

You usually need to re-focus the scope when you change eyepieces because they don't all reach focus at the same spot - could that have been an issue ?.

The sharp image you got with your 32mm eyepiece, although small, should have shown Jupiter as a slightly flattened disk with it's moons strung out either side of it. Even at that low power you could probably just about see the planets 2 main "belts" running across the equatorial regions on the same plane as the moons. Was this the sort of view you had ?.

John

[JohnKA]

Hi, yes using the 32mm I could just about see the 2 main belts and the moons. They were small but crystal clear. The problem came when stepping up the power so to speak, the views lacked the definition that I had with the 32mm turning Jupiter into a round hazy blob with its moons smaller hazy blobs

[George Jones]

There was a shadow transit last night - I saw it with my 5" refractor

Havn't had time to work out which moon it was yet though .....

Ganymede. There is a wonderful table at

http://media.skyandtelescope.com/documents/JphenTab09.pdf.

[John]

Hi, yes using the 32mm I could just about see the 2 main belts and the moons. They were small but crystal clear. The problem came when stepping up the power so to speak, the views lacked the definition that I had with the 32mm turning Jupiter into a round hazy blob with its moons smaller hazy blobs

That sounds like a description of an out-of-focus Jupiter. Did you try racking the focusser slowly in and out with the 15 and 10mm eyepieces in ? - if you did, did you notice the image changing at all ?.

John

[ashenlight]

When I try to view Jupiter with my 3x barlow and 25mm/10mm EP the 'sweet spot' is extremely difficult to find, you've really gotta wind it in and out a few times to get the best position for sharp focus.

[Dazraz]

Hello John great that you found Jupiter last night, I think I know what may be causing your problem as I have experienced what you describe before.

How well you can see objects through telescopes depends on the 'seeing.' This refers to how steady the atmosphere is - their can be 'turbulence' which can upset your image as different levels of air move in different directions causing everything to seem blurry and out of focus. Occasionally, the currents of air all move in the same direction - this is perfect seeing and if you experience this, you'll get fleeting seconds of the most clear views of Jupiter and other objects you are looking at at the time. Seeing differs from location to location, so whilst someone in one place will report good seeing, the person in another location just won't have much luck at all. Tbh, alot of it is down to luck!

As you step up the magnification on an object, as you did moving from a 32mm EP right down to a 6mm EP, you are effectively magnifying the atmosphere too, - at the mag the 32mm EP gives you, the atmosphere wasn't causing you any problems, but once the mag got high enough, you are magnifying all the choppy air currents which affect the image you can see. This is why you couldn't get focus.

It's with this in mind that we should tailor our choice of eyepieces to the conditions on a particular night. DOn't be disheartened if you can't get good focus at high mag one night - enjoy the view of the planet and its moons through a lower mag EP, giving you a larger field of view. Also, stay at the EP for as long as you can - the seeing will improve as the 'turbulence' settles down, giving you those fleeting moments of great conditions I mentioned earlier.

Here's some graphics of Jupiter under bad -> good seeing conditions, to help you get to grips with it Simulated Seeing Animations

Here's an article on the atmosphere and observing, which helped me understand seeing alot when I started out The Atmosphere and Observing - A guide to Astronomical seeing. - How To

I hope this helps you, some people may come forward with different explanations, but I suspect it is the atmosphere that is causing you problems! DOn't forget that Jupiter is still fairly low down for us in the UK - things lower to the horizon are affected more by atmospheric conditions as you have to look through more of the Earth's atmosphere to observe them. Also be aware that buildings and even the ground can give off heat throughout the night that has been collected throughout the day, this can make the air appear to 'boil' above them when viewed through a scope, so affecting your views.

Another possibility is collimation, I hope someone will come forward with some advice about that, as it isn't really my forte. All the best

Very intresting post ashenlight many thanks

[ashenlight]

Glad it's helped you out Dazraz

[Astro Adj]

I'd also like to say thanks Amanda - another very helpful reply for us newbies to study. I never realised there was so much going on up there; a study of our atmosphere would almost be as interesting as the study of everything outside it!

I've been having similar problems with Jupiter (although I seem to be seeing more with each session, which is encouraging), and find it hard to find that 'sweet spot' at high magnifications. I find even the deftest touch on the wheel sends the image jarring all over the place, so can never quite be sure if the image is in focus or not!

[JohnKA]

I have been sticking at looking at Jupiter, some nights are better than others. Following Ashenlights post, I can now recognise the effects of the atmosphere, which I previously thought was down to my scope or maybe even my eyes

As you increase the magnification Jupiter and its Moons certainly skip across the fov very quickly dont they. My son is now saying 'get one of those telescopes with the Motor Drive Dad ' !

[ashenlight]

That's no problem at all Adrian, I'm really pleased it has helped you out too. Isn't it wonderful how astronomy opens up so many different avenues to get interested in? The weather, the atmosphere, physics, photography I think prolonged, consistent (as consistent as the weather and personal commitments will allow) is the key. Get familiar with your object and you will see more detail. It has been so rewarding for me to observe a particular feature on the Moon on successive nights. The change in shadows and highlights is amazing... look at the Moon for long enough and you'll see the terminator creep along You'll begin to find the best focus for the EP you are using (and the atmospheric conditions) the longer you stick with an object. As mag increases it gets harder and harder to keep the object still and at a decent level of focus, I find. Just stay with it, keep notes that you can refer back to to help you out with focusing problems and with picking out detail In this month's S@N mag Sir Patrick Moore says "sporadic viewing is great fun, but more will be gained by specialising." That is so true, and something I can really appreciate after observing objects over consecutive nights. Conditions change, details become more apparent. It's great fun

Great news JohnKA, like I said, sticking with it is the key. Great to hear you are getting to grips with it all I definitely agree on the speed of objects moving across the FOV... it can be so frustrating when you just want to stare but you keep having to adjust the scope's position. Good polar aligning helps with this - once you are polar aligned you only have to adjust the RA axis to stay with the object... of course a motor drive will do all this for you without you having to worry My scope came with a simple motor, I must admit I don't use it very often at all (I just forget about it and when I do remember I can't be bothered, lol) but it has come in handy once or twice, particularly when showing people objects.

Great to hear you are getting on well guys

[andy jack]

Some very helpful replies. I used my new telescope for the first time last night and these words of wisdom were a real help. I say used, it was more of very quick peek during a brief break in the clouds.

No time or the view from my back door to polar align so it was a case of plonking it down and winging it. Found Jupiter no problem but suffered the exact problems described above. I am fairly sure that in my case my collimation is off. I know it is a planet and not a star but when I took it out of focus the rings of light were not symmetrical, just like the diagrams.

If I had not read this and other topics on here, I may have been disappointed with the results from my Telescope. Instead I am encouraged by how much I have read and understood in such a short time.

What I did see in focus may have been small but it was awesome. The tiny pin pricks of light from the moons blew me away.

Can’t wait for the next clear night when I can get it all set up correctly and have a proper look.

[kniclander]

if you were looking at jupiter at just after 11 you may have seen Gannymede emerging from transit - nice

[newbie]

Showed my 80 year old uncle Jupiter last night - it was great to see his reaction and be able to show an 'old' man something he'd never seen before despite a lifetime of experiences. He was like a kid on Xmas morning - really excited. He now wants a scope for Xmas!

[Astro Adj]

I love sharing the sites our scopes can provide with others. I fact I set myself a little goal each session, which is to show my friends / family either a new object or to provide them with a little more information regarding a familiar object.

They seem to enjoy it and it helps me to retain more of the information I'm trying to take in!