Astronomers are puzzled, and that’s putting it mildly. A strange pattern of pulses, repeating like clockwork, has been detected from 3I/ATLAS, an interstellar object cruising through our Solar System.

When we first saw [DiPDoT’s] homebrew computer, we thought it was an Altair 8800. But, no. While it has a very familiar front panel, the working parts are all based on relays. While it isn’t finished, ...