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What to expect!

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I would be interested to know what I could reasonably expect to see from a somewhat light polluted edge of town site using a 120mm refractor. I cannot see the Milky Way and about 20 to 30 stars are all that can be seen without optical aids.

I can get reasonable views of Mars including the polar cap and some fuzzy markings. For Saturn I can seen a white disc and the rings but no details on the planet. Similarly Jupiter I cannot see any markings on the planet. I can split the double star in the plough.

I am using various magnifications up to 200x.

Should I expect to see more detail on the planets or do I need a darker site?


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Have you tried different filters on your EPs?

I find that the planets are so bright on a dark sky that it washes out the colour and contrast on the planets even though I get sharp focus.

My current strategy is to go for the highest mag that I can get good focus with (depending on how good the seeing is) then try various filters.


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I'm surprized you were not getting to see the equatorial belts on Jupiter. These would normally be easier to see than the markings on Mars which you are doing well to see, I think. I don't have an explanation for this. How was Jupiter placed in the sky when you observed?

You would certainly do well to find yourself a darker site. Joining a local astronomical society (you are bound to have one) would provide access to a wealth of experience.


Edited by ollypenrice
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Hello MJP. If you are new to astronomy you may be surprised at how little you can see on the planets with a 120mm refractor (What make/model is it by the way? What eyepieces are you using?). Seeing details takes time, patience, experience & a little luck. Many factors influence what can be seen such as atmospheric disturbance, whether the scope has cooled to the temperature outside, altitude of the object and many, many more! Even with perfect conditions it still takes much practice to see subtle textures and colours etc.

There are very many star clusters and double stars you could see and some globular clusters should be quite impressive with a good 120mm refractor. You need a star map or software to show you where the objects are and practise at 'star-hopping'. I use Sky atlas 2000 and the redshift 4 program. You could watch a variable star vary in brightness by making 2 or more observations over days or weeks, depending how long it takes to go from maximum to minimum. You can still look for the brighter galaxies using medium to high power as this will help maximise ability to see faint details in light-polluted skies. Planetary nebulae can be quite challenging to find.

Good luck!

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I'm between 2 large cities so have a lovely orange glow up to about 30 degrees above the horizon.

I find that a Baader Contrast Boost filter helps on planets, and a Lumicon Deep Sky filter helps on nebula.

I see bands on Jupiter easily but struggle with any detail on Saturn(though seeing the rings makes up for it), Mars is small and although I see ice caps, depending on whats facing us sometimes the planet just looks 'red', sometimes black 'splodges'.

Fundamentally, observing when targets are high and out of the light pollution helps.

I'm using an 8" reflector.

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