On October 25, 1671, the Italian astronomer Giovanni Cassini discovered a new moon at Saturn!
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Iapetus was the second moon anyone had ever found orbiting Saturn, and it was the first of four moons Cassini would discover at the ringed planet. The Dutch astronomer Christiaan Huygens had discovered Titan, the largest of Saturn's moons, about six years earlier. After Cassini found Iapetus, he also found the moons Rhea, Tethys and Dione. When Cassini first saw Iapetus, the moon looked like a tiny speck on the west side of Saturn. He calculated its orbit and thought he would be able to see it again on the east side of Saturn 39 days later, but it was nowhere to be seen. When it reappeared on the west side again, Cassini realized that Iapetus must be darker on one side than the other, which made it harder to see when the dark side was facing Earth. More than 300 years later, NASA sent a spacecraft named Cassini to Saturn, and that Cassini took some pretty awesome photos of Iapetus. Realizing Iapetus kind of resembled a yin-yang, it has since been nicknamed the "yin-yang moon."
‘On This Day in Space’ Video Series on Space.com
Iapetus was the second moon anyone had ever found orbiting Saturn, and it was the first of four moons Cassini would discover at the ringed planet. The Dutch astronomer Christiaan Huygens had discovered Titan, the largest of Saturn's moons, about six years earlier. After Cassini found Iapetus, he also found the moons Rhea, Tethys and Dione. When Cassini first saw Iapetus, the moon looked like a tiny speck on the west side of Saturn. He calculated its orbit and thought he would be able to see it again on the east side of Saturn 39 days later, but it was nowhere to be seen. When it reappeared on the west side again, Cassini realized that Iapetus must be darker on one side than the other, which made it harder to see when the dark side was facing Earth. More than 300 years later, NASA sent a spacecraft named Cassini to Saturn, and that Cassini took some pretty awesome photos of Iapetus. Realizing Iapetus kind of resembled a yin-yang, it has since been nicknamed the "yin-yang moon."
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00:00On this day in space.
00:03On October 25th, 1671,
00:06the Italian astronomer Giovanni Cassini discovered a new moon at Saturn.
00:10Iapetus was the second moon anyone had ever found orbiting Saturn,
00:14and it was the first of four moons Cassini would discover at the ringed planet.
00:18The Dutch astronomer Christian Huygens had discovered Titan,
00:22the largest of Saturn's moons, about 16 years earlier.
00:25After Cassini found Iapetus, he also found the moons Rhea, Tethys, and Diony.
00:29When Cassini first saw Iapetus, the moon looked like a tiny speck on the west side of Saturn.
00:34He calculated its orbit and thought he would be able to see it again on the east side of Saturn 39 days later,
00:40but it was nowhere to be seen.
00:42When it reappeared on the west side again,
00:44Cassini realized that Iapetus must be darker on one side than the other,
00:48which made it harder to see when the dark side was facing Earth.
00:51More than 300 years later, NASA sent a spacecraft named Cassini to Saturn,
00:55and that Cassini took some pretty awesome photos of Iapetus.
00:58Realizing Iapetus kind of resembled a yin-yang, it has since been nicknamed the yin-yang moon.
01:04And that's what happened on this day in space.