Alondra

From Memory Alpha, the free Star Trek reference.

Alondra was an uninhabited planet located in an outer orbit of the Pallas 14 system.

In 2269, the USS Enterprise attempted to intercept an unidentified cosmic cloud that had entered the system near Alondra. However, en route, the crew noticed Alondra disappear from sensors, only to observe that planet was engulfed and consumed by cosmic cloud. (TAS: "One of Our Planets Is Missing")