Hi, everyone. I'm new here so I'll introduce myself: I'm not a physicist, just a physics enthusiast. Although I have studied some physics at school and college, I've never been taught relativity, which I've kind of learned about on my own. My question might seem stupid to you, and I apologise if it is, but I've been thinking about this for some time now, and I can't get to the bottom of it. Here's the thing: The Earth moves at its own orbital speed around the Sun, and so do the other planets in this system. But as they have different distances to the sun, they travel at different speeds. Those speeds relative to the speed at which Earth is moving, I reckon they are pretty big. So, if we ever were to send people to Mars, would their time grow further and further apart from ours every year? I apologise in advance for the weird English (I'm not native), and thanks for any answers you might give me.