Imperium of Man shows up to Sol, what does the society do?

Now sure how many people in this sub are knowledgeable about Warhammer, but I’m just wondering what do yall think would happen if a small fleet of Imperium ships showed up in front of Luna one day?

Obviously, even with the Sword and Scepter and every other armada they have they aren’t doing a thing to the Imperium, but I’m more curious about how Golds would react when they see just a single space marine? Would they treat them like equals, superiors, or maybe how they treat obsidians? Would even a peerless scarred be able to handle, let’s say, an Ultramarine?