While “black moon” is not an official astronomical term, it accurately describes the seemingly invisible lunar event that rarely occurs.

The "black moon," a rare phenomenon that occurs during a new moon phase of the lunar cycle, will occur this weekend. But don't get your hopes up too much, scientists say, because it will be technically invisible. Here's what to know.

In the Portland area, the Black Moon will reach its new moon phase at 11:06 p.m. PDT on Friday, Aug. 22. Since it's mostly going to rise and set with the sun, there won't be much to see — it'll be basically invisible against the brightly-lit sky.