Observing Jupiter 2015

[cotterless45]

This might help, if you are lost in the glare and wondering how others get such wonderful details.

Every 13 months Jupiter reaches opposition,this year on the 6th of February. It'll not only be opposite the Sun , but at it's closest at 365 million miles away. You'll be looking at a very bright gas giant , four times further away than the Sun.

First thing you'll notice is it's flattened shape, the diameter being compressed 13% by gravity. You're seeing a disc 11 Earth diameters in size. You'll spot the equatorial storm belts and the four Galilean moons at low magnification. Galileo found this using his scope ,which had a x30 magnification. Sometimes I wish he was sharing the views now !

Jupiter is best viewed as high above the horizon as you can manage. Warm air from either the ground or buildings will wobble your view. The early hours provide the most stable air and good seeing (stability of image). Any light haze may assist with providing some filtering action to give contrast.

To see significant details you'll be needing 120-x150 magnification. Up to and above x200 is worth trying, but very dependant on the seeing conditions. At higher magnifications focusing can be quite critical even across the width of the disc.

Faster scopes will make focussing more of a challenge, as will spot on collimation in Newtonians. Tube, truss flex and temperature will affect collimation. Not normally an issue for dso's, but quite critical for those finer details. A Barlowed laser is handy at night . A well collimated Newt can provide glorious views to outdo an achromatic refractor.

Now for the brightness. You'll be after some contrast to show the details. Try closing down your aperture, either by fitting the end cap and removing the small inset cap. Ensured this aperture is opposite the focuser. It can sharpen the view and reduce contrast. Try experimenting with bits of card.

Try filters, start with a Moon filter. You might find this too dark if it's the old dark type.

Try a planetary colour filter, I use a light red 23A. A dark blue is also well thought of. To me if really depends on your personal preference. I've found a SW UHC filter useful here, if you can stand a green planet.

Don't try and strain your eye for details. Sitting comfortably helps. Drawing, even a rough sketch will train your eye to tease out more detail and relax. The seeing can change within seconds, so stick with it. The last time that I was observing Jupiter , I stayed absorbed for two hours, noting the transit of the Great Red Spot and belts.

Without filtering , the storm belts are gloriously brown. You'll spot ragged edges and festoons caused by the equatorial area rotating 5 minutes faster than the poles. The whole planets rotates in just under 10 hours. You'll see great changes over an observing session if you keep returning. The moons change position and the Great Red Spot will appear on the outer edge of the southern belt. Transit times on apps are given for when the targets are half way across the disc.

The Great Red Spot is a storm one Earth diameter across,which has been recorded for 300 years. This last year it has paled considerably in colour. Other years it has been a stunning vibrant dark pink, caught in a loop of the belt often accompanied by another lesser spot.

You should spot two further thin belts which define the shaded polar areas. Last year a thin equatorial belt was clearly visible. In 2010, the southern belt disappeared, leaving the GRS stranded . The excitement of viewing planets is never knowing what you might find. I was chatting to an observer at a star party who had seen the comet impact on Jupiter's surface through a very long focal length Dob.

In addition to other features, you'll be able to spot the difference in sizes of the moon discs, Ganymede being the largest. 2014 and this year will provide some fine events as angle of the rotation plane of the moons coincide with ours. Already there have been some eclipsing of moons.

You'll sometimes notice dark circular moon shadows on the disc.harder to see are the white pearl like discs of the moon transiting.

On the 23/24th of January there will be a rare triple transit. At 4.36 Calliso's shadow will be joined by Io. Then Europa's appears at 6.26 and ends at 6.52. Hopefully we'll be gifted with clear skies. Jupiter's Moons is an excellent app to get you started.

Jupiter will be on view all this year and joined by Saturn , which is already rising just before dawn, Nick.

[Special K]

Great stuff, Nick, I wish I had seen something like this a long time ago and only now realising the importance of toning down the brightness on clear nights!

[Qualia]

This is an excellent entry, Nick and thank you for taking the time of putting it together. The review and hints will be a great help to many  . With regards to filters, I've found the Baader Neodymium useful at times. Although there is a slight colour shift, it can help reduce glare and increase contrast on Jupiter.

Looking forward to the night of the 23rd. It's perfect timing for there's no work the next day, so fingers crossed for clear skies across Europe. Curiously, it was probably this month of January so many years ago that Galileo discovered the 4 Galilean Moons .

[StarcrazyGeoff]

As a newcomer to this hobby, this is very useful information and it just so happens, that February 6th is my birthday. Hopefully, we get clear skies and that I will get some decent images of Jupiter with my new Orion Starblast 4.5" Reflector.

What a birthday present to look forward to!  Thank you for sharing this information. 

[ghostdance]

As a newcomer to this hobby, this is very useful information and it just so happens, that February 6th is my birthday. Hopefully, we get clear skies and that I will get some decent images of Jupiter with my new Orion Starblast 4.5" Reflector.

What a birthday present to look forward to!  Thank you for sharing this information. 

Happy Birthday in advance!

But....assuming you mean photography, images with the 4.5" could be difficult. It's a Newtonian Dob meant for visual, so no tracking...you may be able to take a pic using a compact directly through the eyepiece but I only tried this once (on Saturn) and the result was just a white blob (pilot error was essentially the cause methinks). I've stuck to purely visual ever since.

Oops: it's just occurred to me you probably mean sketching, so just ignore the above!

Tsk, too many ristrettos for me today - leaping in without thinking!

[Sirius Starwatcher]

Thank you for the post Nick better info,than most astro mags give out. Here's hoping Feb 6 rolls in with clear skies

[StarcrazyGeoff]

Happy Birthday in advance!

But....assuming you mean photography, images with the 4.5" could be difficult. It's a Newtonian Dob meant for visual, so no tracking...you may be able to take a pic using a compact directly through the eyepiece but I only tried this once (on Saturn) and the result was just a white blob (pilot error was essentially the cause methinks). I've stuck to purely visual ever since.

Oops: it's just occurred to me you probably mean sketching, so just ignore the above!

Tsk, too many ristrettos for me today - leaping in without thinking!

No I won't be taking photographs, just visual observing. If I get decent views, I might try sketching what I see. Just for my records.

[Astro Imp]

Well done Nick, an excellent and timely post, thanks.

[John]

Excellent post Nick with some great tips

I'm not an advocate of reducing the aperture of the scope though for the same reasons that have been discussed recently in a thread on the need, or not, for lunar filters.

I find the key ingredients that contribute to good views of Jupiter are decent seeing conditions and time spent at the eyepiece. It's amazing how the eye trains itself over a period of time and the subtle details start to show themselves

[bingevader]

Thanks Nick, fab post.

[jabeoo1]

Lovely informative writing Nick.  Thank you 

[Quill]

Thanks for this post - I've been browsing the forum since I got my first scope for Christmas, and this post was really useful for me when viewing Jupiter last night.

It was amazing to be able to see colour detail from my own back garden!