Three moons appear to be parading over Jupiter simultaneously, casting shadows upon Jupiter's clouds in this video.
For a decade, this "grand slam" event of a triple eclipse and "triple transit", won't be repeated.
This video also shows Ganymede, the largest moon in the solar system, passing by Europa.
Jupiter and its largest satellites performed a rare dance recently.
Three of Jupiter's huge moons, Europa, Ganymede and Callisto, paraded simultaneously across Jupiter's swirling surface, casting their shadows onto the clouds below.
Christopher Go, an amateur Filipino astronomer, captured images of the spectacle at midnight on August 15. These images were then compiled by Kunio Sayanagi (a planetary scientist at Hampton University) into the video below.
Christopher Go/Kunio Sayanagi
Every second of the video is 30 minutes of actual time.
Go shared his thoughts with Insider, "I knew what was coming but it was surreal to see it in person."
He wrote a blog post saying that he had been waiting all year for the "grand slam" event.
The area in the shadows of these lunar moons would be visible from the surface of Jupiter and it would appear as a solar eclipse. This occurrence, however, is known as a "transit" from Earth because the moons transit Jupiter. Many transits occur each year on Jupiter. It's not common for three transits to happen at once. According to Sayanagi the last triple transit occurred in 2015. The next one will not occur until 2032.
Insider reported that Sayanagi said, "This is very difficult data to capture." "I believe this is the greatest movie of Jupiter's triple transit."
Go was particularly fortunate to capture this footage as it was the middle of the monsoon season here in the Philippines. Although it rained almost every night during the triple transit week, the skies cleared just in the right time for Go to set up his telescope and observe the Jovian trio marching across the planet's bands.
One moon briefly eclipses another
This video is not just about the triple transit. The yellow-hued Io, which is zipping behind Jupiter at the beginning of the video, makes a brief appearance. About halfway through, Europa crosses between Ganymede & Jupiter.
Europa, a tiny icy world that has an ocean below its surface, briefly vanishes behind Ganymede. The little moon is visible being eclipsed by Ganymede's shadow as it reappears.
Europa (right), emerges behind Ganymede, left, with the larger moon's silhouette eclipsing. Christopher Go
Go stated, "That was really thrilling was to see the shadow Ganymede split." "Half of Europa and half on Jupiter's surface."
Ganymede, the largest moon in our solar system, has its own hidden ocean just like Europa. Scientists believe that these moons may have subsurface oceans that could be home to alien life.
Galileo Galilei was the first to see the four moons in this 1610 video Europa, Ganymede and Callisto. This was the first time anyone had ever documented objects orbiting another world. Galileo thought that perhaps Earth wasn't at the center of the universe.
Sayanagi stated, "We all know this today, but even then it is amazing to see the moons circle Jupiter casting shadows and eclipsing one another."
Scientists believe Jupiter may have 79 moons. However, the remaining moons are smaller than the Galilean moons.
Europa as seen by NASA's Galileo spacecraft late 1990s. NASA/JPL-Caltech/SETI Institute
Even without its moons Jupiter's colorful clouds, raging storms and brilliant stars make for an amazing astronomical spectacle.
Go, who owns a furniture business with his wife, said that he has been watching Jupiter since 2003. "Jupiter's dynamic nature means that you can see the changes every day."