Is an object moving around earth (orbiting) at a constant speed accelerating?

I swear my teacher loves to ask tricky questions!!! I'm in a basic astronomy class and we're learning about Newton's Laws (gravity etc). One of the questions my teacher has asked on homework is, "An object in orbit around the Earth, like the Space Station, moves with a constant speed called the circular velocity. Is an object moving around the Earth at a constant speed accelerating? Explain why or why not." I want to say that the object is not accelerating because it is at a constant speed... Acceleration refers to how rapidly the change in velocity happens and if the speed is constant, then there is no change in velocity occuring. Is that right??? Can anyone explain this to me?