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Saturn's hexagon

space Maturity 5-7 Next article →

Saturn has a very strange cloud pattern at its north pole.

PIA20513 - Basking in Light
PIA20513 - Basking in Light

This shape is a hexagon, which means it has six sides. The sides are huge. Each side is about 13,800 kilometers long. This is even longer than the diameter of Earth! The whole shape is a jet stream. This is a fast wind made of gases. The wind moves at 360 kilometers per hour. It stays in one place as the planet turns. This makes it different from other clouds on Saturn.

PIA21611 - Saturn's Hexagon as Summer Solstice Approaches
PIA21611 - Saturn's Hexagon as Summer Solstice Approaches

Scientists are still learning how this shape works. One idea is that it forms at a wind boundary. This happens when winds move at different speeds. In a lab, scientists spun liquid in a tank. They spun the center and the edges at different speeds. This created regular shapes like hexagons. On Saturn, many small storms might push the boundary into a shape. These small storms are called vortices. They space themselves out evenly around the edge. This helps keep the hexagon shape steady.

Saturn north polar vortex false color
Saturn north polar vortex false color

We first saw this shape because of space missions. The Voyager mission flew by Saturn in 1981. David Godfrey discovered the hexagon in 1987. He did this by looking at the Voyager photos. Later, the Cassini mission visited Saturn in 2006. Cassini took many great pictures of the pole. It even took a video of the weather. The spacecraft moved at the same speed as the planet. This allowed us to see the hexagon's movement.

PIA21611 - Saturn's Hexagon as Summer Solstice Approaches
PIA21611 - Saturn's Hexagon as Summer Solstice Approaches

Saturn's hexagon also changes its look over time. Between 2012 and 2016, the color changed. It used to look mostly blue. Then it changed to a golden color.

PIA21611 - Saturn's Hexagon as Summer Solstice Approaches
PIA21611 - Saturn's Hexagon as Summer Solstice Approaches

Cassini saw this change happen. One idea is that sunlight creates haze. This happens when the pole is exposed to more sun. This change is linked to the seasons on Saturn. The hexagon is located at about 78 degrees north. It rotates at the same speed as Saturn's radio signals.

PIA20513 - Basking in Light
PIA20513 - Basking in Light

It is helpful to think of the hexagon like a spinning top. A spinning top stays in one spot while it turns. The hexagon does the same thing on the planet. It does not drift away like other clouds. You can also think of the wind like a fast river. The hexagon is a river of gas shaped like a ring. It sits around a large storm called a vortex. This vortex is also at the north pole. Saturn's south pole does not have a hexagon. It only has a vortex there.

Saturn north polar vortex false color
Saturn north polar vortex false color
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🖼️ Images & Media (3)
File:PIA20513 - Basking in Light.jpg
PIA20513 - Basking in Light.jpg
File:PIA21611 - Saturn's Hexagon as Summer Solstice Approaches.gif
PIA21611 - Saturn's Hexagon as Summer...
File:Saturn north polar vortex false color.jpg
Saturn north polar vortex false color.jpg
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