Nice start Kev
Composition is good.
Just wondering if your focussing is off though.
At 14mm on a D800, you should be sharper than that i would expect.
Infinity is sometimes way off the infinity marker on the lens.
On my Sigma lens, infinity is a mile away from the marker.
I use liveview at max ISO, zoomed in fully on a bright planet or star first to get the focus right, by making it as small a point of light on the screen as possible. Then adjust the ISO back down and leave the focus alone in manual mode.
Keep at it though
Cheers
Bob