If you’re flying your ship in game mode, you can’t see most of it, because you’re inside it. All you can see is the cockpit and instruments.
Because you can’t see your ship while you’re flying, Hello Games decided to save resources by not rendering it. All that gets rendered is the cockpit frame, and the instrument panel.
Normally you’re not aware of this - but every now and then, if you get yourself at just the right angle between the sun and a planet, you can see your own shadow. It’s quite unsettling to realise you’re flying round the universe in little more than a greenhouse.