To celebrate the 10th anniversary of Cassini's Saturn orbit insertion, <a target="_blank" target="_blank">NASA has listed</a> the top 10 things we wouldn't know if the spaceship hadn't traveled to the ringed planet. <strong>Also</strong>: <a target="_blank">Cassini images of Saturn and its moons.</a>
Cassini's top 10 discoveries about Saturn —
To celebrate the 10th anniversary of Cassini's Saturn orbit insertion, NASA has listed the top 10 things we wouldn't know if the spaceship hadn't traveled to the ringed planet. Also: Cassini images of Saturn and its moons.
NASA/JPL
10. First complete view of the north polar hexagon and discovery of giant hurricanes at both of Saturn's poles. Saturn's polar regions have surprised scientists with the presence of a long-lived hexagonal-shaped jet stream in the north and hurricane-like storms at both poles. The driving forces of each remain a mystery.
Cassini's top 10 discoveries about Saturn —
10. First complete view of the north polar hexagon and discovery of giant hurricanes at both of Saturn's poles. Saturn's polar regions have surprised scientists with the presence of a long-lived hexagonal-shaped jet stream in the north and hurricane-like storms at both poles. The driving forces of each remain a mystery.
NASA/JPL-Caltech/SSI/Hampton University
9. Mystery of the dual bright-dark surface of the moon Iapetus solved. The origin of Iapetus' two-faced surface has been a mystery for more than 300 years. The Cassini spacecraft solved the puzzle, showing that dark, reddish dust in Iapetus' orbital path is swept up and lands on the leading face of the moon.
Cassini's top 10 discoveries about Saturn —
9. Mystery of the dual bright-dark surface of the moon Iapetus solved. The origin of Iapetus' two-faced surface has been a mystery for more than 300 years. The Cassini spacecraft solved the puzzle, showing that dark, reddish dust in Iapetus' orbital path is swept up and lands on the leading face of the moon.
NASA/JPL/Space Science Institute
8. Study of prebiotic chemistry on Titan. Titan's atmosphere is the most chemically complex in the solar system. Here, bodies of liquid near Titan's north pole can be seen.
Cassini's top 10 discoveries about Saturn —
8. Study of prebiotic chemistry on Titan. Titan's atmosphere is the most chemically complex in the solar system. Here, bodies of liquid near Titan's north pole can be seen.
NASA/JPL
7. Vertical structures in the rings imaged for the first time. Once about every 15 years, the sun shines on the edge of the ring plane and northern and southern sides of the rings receive little sunlight. Cassini measured the thick, long shadows from this rare event to determine the heights of structures within the rings.
Cassini's top 10 discoveries about Saturn —
7. Vertical structures in the rings imaged for the first time. Once about every 15 years, the sun shines on the edge of the ring plane and northern and southern sides of the rings receive little sunlight. Cassini measured the thick, long shadows from this rare event to determine the heights of structures within the rings.
6. Radio-wave patterns shown not to be tied to Saturn's interior rotation as previously thought. Saturn emits radio waves known as Saturn Kilometric Radiation. A similar radio wave pattern was measured at Jupiter to deduce the length of that planet's day. However, it was discovered that the variation in radio waves controlled by the planet's rotation is different in the northern and southern hemispheres. The northern and southern rotational variations also appear to change with the Saturnian seasons and the hemispheres have actually swapped rates. Saturn's length of day is still not known.
Cassini's top 10 discoveries about Saturn —
6. Radio-wave patterns shown not to be tied to Saturn's interior rotation as previously thought. Saturn emits radio waves known as Saturn Kilometric Radiation. A similar radio wave pattern was measured at Jupiter to deduce the length of that planet's day. However, it was discovered that the variation in radio waves controlled by the planet's rotation is different in the northern and southern hemispheres. The northern and southern rotational variations also appear to change with the Saturnian seasons and the hemispheres have actually swapped rates. Saturn's length of day is still not known.
NASA/JPL-Caltech/University of Iowa
5. Studies of the great northern storm of 2010-2011. In 2010 Cassini got a front-row seat to a massive storm that disrupted Saturn's relatively tranquil atmosphere. The largest temperature increases recorded for any planet were measured. Molecules never before seen in Saturn's upper atmosphere were detected. The storm diminished shortly after its head collided with its tail, a little less than a year after it began. Saturn's rings are seen as the thin blue line in this image, due to the filters used to show methane absorption. The rings are outside the atmosphere, and therefore are not affected by methane absorption.
Cassini's top 10 discoveries about Saturn —
5. Studies of the great northern storm of 2010-2011. In 2010 Cassini got a front-row seat to a massive storm that disrupted Saturn's relatively tranquil atmosphere. The largest temperature increases recorded for any planet were measured. Molecules never before seen in Saturn's upper atmosphere were detected. The storm diminished shortly after its head collided with its tail, a little less than a year after it began. Saturn's rings are seen as the thin blue line in this image, due to the filters used to show methane absorption. The rings are outside the atmosphere, and therefore are not affected by methane absorption.
NASA/JPL-Caltech/Space Science Institute
4. Titan revealed as Earth-like world with rain, rivers, lakes and seas. Titan is the only known place in the solar system, other than Earth, that has stable liquid on its surface. Rather than water, its lakes are made of liquid ethane and methane.
Cassini's top 10 discoveries about Saturn —
4. Titan revealed as Earth-like world with rain, rivers, lakes and seas. Titan is the only known place in the solar system, other than Earth, that has stable liquid on its surface. Rather than water, its lakes are made of liquid ethane and methane.
NASA/JPL-Caltech/University of Arizona/University of Idaho
3. Saturn's rings revealed as active and dynamic. Cassini's mission allowed scientists to observe changes in Saturn's dynamic ring system, including what could be the birth of a moon. The disturbance, visible in the lower left of this image, is thought to be an icy body migrating out of the ring, believed to be part of the process required to form a moon.
Cassini's top 10 discoveries about Saturn —
3. Saturn's rings revealed as active and dynamic. Cassini's mission allowed scientists to observe changes in Saturn's dynamic ring system, including what could be the birth of a moon. The disturbance, visible in the lower left of this image, is thought to be an icy body migrating out of the ring, believed to be part of the process required to form a moon.
NASA/JPL-Caltech/Space Science Institute
2. Icy plumes on Saturn's moon Enceladus. Here, the plumes can be seen back-lit by the sun. The discovery was such a surprise that the mission was completely reshaped to get a better look. Evidence of water-based ice in the plume excited scientists further, as life as we know it relies on water.
Cassini's top 10 discoveries about Saturn —
2. Icy plumes on Saturn's moon Enceladus. Here, the plumes can be seen back-lit by the sun. The discovery was such a surprise that the mission was completely reshaped to get a better look. Evidence of water-based ice in the plume excited scientists further, as life as we know it relies on water.
NASA/JPL/Space Science Institute
1. The Huygens probe makes first landing on a moon in the outer solar system. The Huygens probe's historic landing in 2005 was the most distant to date. In addition to providing this photo, the probe found the moon to be similar to Earth before life evolved, with methane rain, erosion, drainage channels and dry lake beds.
Cassini's top 10 discoveries about Saturn —
1. The Huygens probe makes first landing on a moon in the outer solar system. The Huygens probe's historic landing in 2005 was the most distant to date. In addition to providing this photo, the probe found the moon to be similar to Earth before life evolved, with methane rain, erosion, drainage channels and dry lake beds.
ESA/NASA/JPL/University of Arizona