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mbaddah
06-11-2007, 11:13 AM
Hi everyone

I currently own a 6" Dobsonian with few Plossl eyepieces. Currently when viewing Jupiter, it looks like a small white circle (half the size of a 5c coin) and can see the moon. However, i would love to see some detail on the planet, especially the red spot. Do i need a bigger scope? Different eyepieces?

Many thanks for your help in advance.

mrsnipey
06-11-2007, 11:37 AM
Hi there, I have a 12" dob and I can see 4 of Jupiter's moons (possibly 5 - not sure yet). I can also see the bands on the surface quite clearly but I can't see the red spot.

I'm not sure if that means it's not visible at the moment or I need a better scope.

janoskiss
06-11-2007, 11:49 AM
Your scope and EPs are plenty good enough to show you a fair amount of detail including the GRS. You just need a bit of patience, practice and reasonable conditions. Try when the planet is higher up in the sky (soon after sunset atm) and when the atmosphere is not too turbulent. Magnification of 100-150x (8-12mm EP). Also keep in mind that the GRS is not always on the side of the planet facing us - but you should be able to see cloud bands anytime: they run in parallel with the approx line of the 4 moons.

astronut
06-11-2007, 11:54 AM
A 6" aperture is plenty for viewing Jupiter (and Saturn)
With all things being equal (sky conditions etc) you will see the four largest moons and the G.R.S. with a 60mm scope, approx 90X is needed.
You will need Astronomy 2007 or a suitable planetarium program to show you when the G.R.S will be facing Earth.
The bigger the aperture will allow greater detail to be seen.
I hope this helps to answer your questions.:thumbsup:

Astroman
06-11-2007, 12:08 PM
I had a 4" TAL-1 Newtonian, could see the spot no worries with a TV 15mm Plossl and 3x Barlow.

Geoff45
06-11-2007, 01:28 PM
I took this pic of Jupiter on the left with a 4" refractor. You can clearly see the RS. It looks pretty similar visually at the brief moments of good seeing.
So 4" is certainly good enough. If a 6" won't show detail on Jupiter, I'd be having a look at the collimation.
Geoff

§AB
06-11-2007, 02:21 PM
The GRS is an easy catch in my 4.5" reflector. It can be seen with closed eyes in my 10".

A 6" should be able to catch it easily, try using magnifications around 150x to make it easy to pick out. If you can't see the spot, it isn't facing us or seeing is extremely poor.

vash
06-11-2007, 02:26 PM
One thing that can help is make sure that your focus is really good and also don't just look at the planet but Observe it. You won't believe what you can see if you just look at it for a while, the longer you look the better chance you have of getting good patch of seeing.


another thing I found that helps when looking for detail on planets are colour filters. I have a light blue filter that makes surface detail more visible though these are not necessary.

ving
06-11-2007, 02:34 PM
yup, make sure the seeing is good and you should see stax of detail including teh grs. make sure your collimation is good too. :) dont over magnify it!

rumples riot
06-11-2007, 05:54 PM
Planetary observing is a skill, however you need these things.

1. for the objective to be at ambient or as near to it as possible. If it is going to be 15 degrees just after sunset, try to putting the scope in the shade for 1.5 hours before sunset and point it straight up.

2. The scope must be well collimated, some collimation tools are ideal for this, and worth the money. Try cats eye collimation tools. The best there is and really work. Simple to use.

3. The seeing has to be good. Meaning the differing levels of air masses that make up the atmosphere have to be relatively calm. Getting to know the pickering scale is worth while and will help you to identify what the seeing is like.

4. The Jet Stream has to be either low or non existent.


With those you can start to see what is going on. Try getting Jupiter 2 for GRS timings. Nice program and very easy to use.

Geoff45
06-11-2007, 06:31 PM
One of the best ways to see planetary detail is to sketch the planet. You get to glimpse various details and putting them down on paper fills in the whole picture. If you do this for a couple of weeks you'll be amazed at the difference in your sketches as time progresses.
Geoff

MikeyB
06-11-2007, 07:20 PM
Simply brilliant (make sure your local time is set correctly):

http://www.astrosurf.com/rondi/programmes/index.htm

Besides a representation of Jupiter's satellites around the planet and current location of the Great Red Spot (which isn't actually very red at all nowdays, alas), the software shows the satellites' shadows crossing Jupiter's disk, and satellites' eclipses into Jupiter's shadow.

Stephen65
06-11-2007, 09:44 PM
Seeing is important but the thing with Jupiter is that the more you look at it the more you train your eye to see and the more you will pick up. I can see it in my 5" refractor from about 130x

And yes, its more like the Great Salmon Spot these days.

ausastronomer
06-11-2007, 10:49 PM
Hi,

You will only see the 4 Galilean moons in a 12" telescope. The other moons are all less than 1/10th the size of the Galilean moons and the brightest of them, "Amalthea" is only Mag 14.6. To compound this it is far too close to Jupiter and in its glare to enable it to be seen in most amateur telescopes. You would need at least a 25" telescope under the most perfect of conditions in terms of the satellites placement to the planet, seeing and transparency to stand even a remote chance of seeing any more than the 4 Galilean Moons in a 25" scope. Amalthea was discovered by Barnard in the 36" Lick refractor. The "5th" satellite you were hoping for was most definately a field star.

Cheers

mrsnipey
07-11-2007, 09:02 AM
Doh, it must have been a star in the background. :doh:

I saw something that looked like a fifth moon and I drew a picture so I could check it out the next night but it's been cloudy ever since.
:cloudy: