Is it aliens?

 No, it's a magnetar, but it's fascinating. It's a fast radio burst...that's about 1,000 times longer/slower than average with a clear pattern.

The signal itself had a heartbeat inside it. It's from a long way away. And it's peculiarly consistent.

What is it? A magnetar or pulsar that is, for whatever reason, rotating much more slowly than average. One day we'll understand how these things work. One day...