During the recent lunar eclipse (the date on which it occurred depends upon your time zone: mid-eclipse was at 05:12 UTC on 2019-01-21, while the eclipse occurred on the evening of January 20th in western hemisphere time zones) several amateur astronomers capturing the eclipse on video observed a flash of light, just a single video frame, near the limb of the eclipsed Moon just at the beginning of the umbral phase.
The fact that three observers in different locations have so far reported the same flash excludes other explanations such as a reflection off an Earth satellite or a “point meteor” burning up in the Earth’s atmosphere on a trajectory pointed directly at the observer.
This is not the first time an impact has been observed on the Moon. A number of observers monitor the dark portion of the Moon for flashes of impacts, some using both infrared and visual sensors. An infrared sensor can observe the afterglow of the impact and provide an estimate of the energy released by the event. Follow-up observations by the Lunar Reconnaissance Orbiter have, on several occasions, found the fresh craters created by observed impacts. This is, however, the first impact observed during a lunar eclipse. This has no scientific significance whatsoever, but it’s cool. The people who saw it were the first humans ever to witness such an event. I’ve observed another event never seen by a human before the day I spotted it, and it’s something I’ll long remember.
Here is a video by Scott Manley about the event and other observations of lunar meteor impacts.