Coloured caps on jupiter

[dave34]

Hi folks, ive just been taking a look at jupiter, i found that i couldnt get a crisp view, four moons were there, i could just make out the two main belts around the planet, but on higher mag,with a cheap barlow and stock 10mm EP i was getting a very orange edge around the upper half of the planet and a very pretty blue around the bottom edge, is this a collimation issue, or something else,.your advice much appreciated. cheers Dave

[Daniel-K]

I would say ttrying to get focus with a 10mm barlowed is too much for the scope you need very steady nights for that. As for the blue fringe ?? No idea

[moriniboy]

Seems to me like you are seeing CA (chromatic aberration) do you have a refractor or reflector, most refractors suffer from CA when viewing bright objects like Jupiter and Venus.

Look it up on Wiki for more ingo

[dave34]

Sorry, i should have given more detail, i started off with the stock 25mm EP, the views with this EP were fine, it was trying to use greater mag with the 10mm and x2 Barlow that these symptons arose, it was a very clear night and the seeing seemed good, although to view Jupiter i was viewing over a neighbours roof, could the heat rising from the house be the cause? .

[DarkerSky]

I would say that you were suffering from Jupiter being quite low down last night in a turbulent upper atmosphere. I was on Jupiter between 2am and 3am. Seeing was pants with loads of wobble. Poorest view for quite some time even though the sky was gorgeously clear. The colours you mention are likely caused by refraction through the currently very warm upper atmosphere over the UK.

[John]

I would say that you were suffering from Jupiter being quite low down last night in a turbulent upper atmosphere. I was on Jupiter between 2am and 3am. Seeing was pants with loads of wobble. Poorest view for quite some time even though the sky was gorgeously clear. The colours you mention are likely caused by refraction through the currently very warm upper atmosphere over the UK.

I think this diagnosis is spot on. I was experiencing the same last night as I was being impatient and not waiting for Jupiter to rise sufficiently high in the sky before observing it. My scope and eyepieces do not normally show any false colour even on bright objects.

Wait until Jupiter is higher in the sky and I reckon this effect will disappear.

[dave34]

I was a bit impatient lastnight, jupiter was very low in the sky when i was viewing it, i must be more patient. cheers folks

[sunshine185]

Jupiter was just a white blob for me last night until around 2am.

[LukeSkywatcher]

Sounds like CA to me.

[Moonshane]

I was getting good detail about 1am but will be better as it rises earlier.

[Astrosurf]

I often get this colour problem with planets and was told it was atmospheric refraction. It's a bit annoying but, when I image, I can take it out with Registax. As you can see from my sig block I have good EPs and a reflector, so no CA!

[Astrosurf]

See here: http://www.astropix.com/HTML/L_STORY/VD.HTM

[John]

I often get this colour problem with planets and was told it was atmospheric refraction. It's a bit annoying but, when I image, I can take it out with Registax. As you can see from my sig block I have good EPs and a reflector, so no CA!

I agree - it's not CA. Atmospheric refraction has the effect of showing different colours at the top and bottom of an object as the OP describes whereas CA is a consistent colour all around the object.

[dave34]

Thanks Astrosurf, that link describes what i was seeing, good link, cheers dave

[Astrosurf]

It's a pleasure. I'm glad I found it too! Now saved to my favourites.