After 69 years, the pitch has finally dropped. Researchers at Trinity College who have been conducting one version of the most famous long-term experiment in the world—dubbed the pitch drop experiment—have finally recorded a drop of pitch dropping.

This might not sound like a big deal, but it’s actually quite an interesting physics problem. There are actually two pitch drop experiments set up right now. One is at Trinity College, and another, older one, is at the University of Queensland. This Australian version is possibly the longest running physics experiment ever. The University of Queensland explains the setup:

In 1927 Professor Parnell heated a sample of pitch and poured it into a glass funnel with a sealed stem. Three years were allowed for the pitch to settle, and in 1930 the sealed stem was cut. From that date on the pitch has slowly dripped out of the funnel – so slowly that now, 83 years later, the ninth drop is only just fully formed.

Here’s a time lapse video of their experimental setup:

But due to technical difficulties, the University of Queensland still hasn’t seen their pitch drop. Trinity University, on the other hand, after 69 years of watching just captured their drop on camera. Well actually, they didn’t quite watch for 69 years*. In fact, they sort of forgot about the experiment entirely. Nature reports:

Over the years, the identity of the scientist who began the experiment was forgotten, and the experiment lay unattended on a shelf where it continued to shed drops uninterrupted while gathering layers of dust. Physicists at Trinity College recently began to monitor the experiment again. Last April they set up a webcam so that anyone could watch and try to be the first person ever to witness the drop fall live.

The University writes:

A number of weeks ago, scientists in the department noticed that a drip had formed. In order to finally and definitively end the experiment, they set up a webcam to video the experiment around the clock. Last Thursday, the drip finally dropped into the jar, and was captured on camera.

Radiolab explains the experiment too:

The Australians are still waiting though*.

This story has been updated to reflect the forgetting and remembering of the experiment, and the fact that there is no Nature paper as of yet.

More from Smithsonian.com:

Physicists Have Been Waiting For This Painfully Slow Experiment for Nearly 86 Years