Warning: My star trail photos keep coming out blurry no matter what I try

I spent hours last night trying to capture clean star trails in my backyard. I used a sturdy tripod and set my camera for a long exposure. But every single shot has these weird, jagged lines instead of smooth arcs. I've read all the guides online and followed them to the letter. It's driving me crazy because I see other people's photos that look perfect. What am I missing here? Is there some secret trick I don't know about?