Thanks to the big Little Engine That Could energy of some diligent diggers and tug boats, the 220,000-ton container ship Ever Given is no longer blocking the Suez Canal. It took roughly six days to shift enough mud away from the ship’s bow and stern to set it back on course, but the rescue mission wasn’t accomplished only by human-made machines. As CNN reports, the moon helped, too.

The tides in Earth’s bodies of water are created by the gravitational forces of both the moon and sun, and the effects of those forces are collectively stronger when the Earth, moon, and sun are all in line with each other. This happens during every full moon—when the Earth is between the moon and sun—and during new moons, when the moon is in the middle. The increased force causes what’s called a “spring tide.” Basically, Earth’s waters bulge out a little more than normal, and the tides are a little higher than normal. (The name isn’t a reference to the season, but rather the idea that tides “spring forth” during full and new moons.)

Spring tides and their more moderate counterparts, neap tides.National Oceanic and Atmospheric Administration

A full moon occurred on Sunday, March 28, when the Ever Given had been wedged between the banks of the canal for about five days. This March’s full moon, traditionally known as the “worm moon” because earthworms’ digested matter starts fertilizing soil around March, wasn’t a regular one. It was a supermoon: a full moon that looks extra large and bright because it coincides with the perigee, or the point in the moon’s orbit when it’s closest to Earth. Its perigee came just two days later, on March 30.

Since the moon was especially close to Earth when the full moon occurred, the spring tide was even more significant than it would’ve been during a normal full moon. According to NASA Earth Observatory, the Suez Canal’s water level measured as much as 1.5 feet higher than usual on March 29. As the tug boats worked to dislodge the Ever Given, the extra high tide provided a critical bit of help, and it finally floated free that same day.

“In effect, you have the forces of nature pushing hard with you and they pushed harder than the two sea tugs could pull,” Peter Berdowski, CEO of Boskalis, the dredging company responsible for unsticking the ship, said during a Dutch radio interview.

[h/t CNN]