I'm also fairly new to photography and have been playing around over the past week (mainly lunar pics at the moment though).
I would try having perhaps a lower iso with the longer shutter speed, or you may need to change the aperture, making the f stop (is that right?) a higher value (therefore smaller aperture).
Those are just guesses and what I would try doing. So you will most likely still need input from the pros here
P.s. I love the second pic of Jupiter you've got there. I need to get my lazy bum out of bed early so I can have a crack at it.