NASA’s Juno spacecraft has provided the first close-ups of Jupiter’s biggest moon in 20 years. Juno zoomed past icy Ganymede on Monday, passing within just 645 miles (1,038 kilometres) of its surface. The last time a spacecraft came anywhere near that close was in 2000, when NASA’s Galileo spacecraft swept past our solar system’s biggest moon.

NASA released Juno’s first two pictures of Ganymede on Tuesday that show craters and long, narrow features possibly related to tectonic faults. One shows the moon’s far side, facing away from the Sun. “This is the closest any spacecraft has come to this mammoth moon in a generation,” said Juno’s lead scientist, Scott Bolton, of the Southwest Research Institute in San Antonio.

“We are going to take our time before we draw any scientific conclusions, but until then we can simply marvel at this celestial wonder – the only moon in our solar system bigger than the planet Mercury.”

Ganymede is one of 79 known moons orbiting Jupiter and discovered by the Italian astronomer Galileo Galilei in 1610, along with Jupiter’s three next-biggest moons. Launched a decade ago, Juno has been orbiting Jupiter for five years. Its suite of sensitive instruments has enabled us to see Ganymede like never before.