Decagon-shaped atmospheric wave found on Saturn’s south pole

Scientists have discovered a strange shape hovering over Saturn – but it’s not a UFO.

Observations from NASA’s Hubble Space Telescope show a giant, 10-sided atmospheric wave around Saturn’s south pole that researchers believe could continue to develop.

The decagon* has similarities and differences to the hexagon that was discovered in the 1980s at its north pole, according to NASA, with scientists believing it could be a new atmospheric phenomenon.

The study was led by Spain’s University of the Basque Country researcher Professor Agustín Sánchez-Lavega and was published in the journal Science Advances.

Prof Sanchez-Lavega, along with amateur astronomers Trevor Barry and Jean-Paul Oger, first noticed the strange formation in 2024 in images taken from Earth. NASA said the images were submitted to the advanced database at Planetary Virtual Observatory Laboratory, a Basque Country University-run site.

More images taken last year prompted further investigation.

According to NASA, the discovery was made possible because Saturn’s shifting seasons slowly brought the planet’s south pole back into view from Earth. This change made it possible for astronomers who analyse images of Saturn from the ground to identify it.

After noting the formation using multiple on-the-ground observations from astronomers, the research team then turned to the Hubble telescope* for a better view.

“Given Saturn’s symmetry in its north-south jet stream* system, we have been searching for a counterpart to Saturn’s northern hexagon on the south pole in Hubble images since 1990,” Prof Sanchez-Lavega said on NASA’s official site. “Images from NASA’s Cassini spacecraft, which orbited Saturn between 2004 and 2017, showed no inkling of a long-lived formation, either. The Hubble data confirmed the feature’s presence back to 2023.”

Looking back to 2023 using Hubble observations from the Outer Planet Atmospheres Legacy* (OPAL) program, researchers found subtle clues of the structure beginning to form before becoming clearly defined, NASA said.

Study co-author and NASA’s Goddard Space Flight Center OPAL principal investigator Dr Amy Simon said NASA had never seen “anything quite like this in Saturn’s southern hemisphere.”

“The northern hexagon has been there every time we’ve looked for more than 40 years. This feature is different — it appears to be strengthening, giving us the rare opportunity to watch a giant atmospheric pattern develop,” she said on NASA’s official site.

According to NASA, the decagon is positioned within one of Saturn’s powerful jet streams and runs through multiple layers of the atmosphere. Scientists said the phenomenon “isn’t just a cloud-level feature, but a vertically extended atmospheric structure.”

Images from Hubble have also shown the decagon’s position can shift slightly depending on the wavelength of light observed. A report from the Associated Press states that while the hexagon tends to stay put, the decagon moves eastwards at about 10km/hr.

According to AP, one side of the decagon measures more than 16,700 km.

“The most intriguing part to me is that this seems to have just formed recently,” said Dr Simon. “The question is, why did it suddenly form now when we haven’t seen one before?”

Prof Sanchez-Lavega told AP in an email that the discovery of the decagon was significant because it meant the planet’s hexagon, which was previously considered unique, might not be “as extraordinary as we thought.”

University of Leicester’s Professor Leigh Fletcher was responsible for measuring the wind in the decagon using the European Southern Observatory’s Very Large Telescope in Chile, AP reported.

“Saturn still has the ability to surprise us,” Prof Fletcher told the news agency in a statement.

“This is a highly interesting phenomenon that appears to be unique to Saturn, and we want to know why.”

In the statement provided to AP, Prof Sanchez-Lavega reportedly wondered whether the unique geometric disturbances were related to cyclones on Jupiter, which also appear in polygonal shapes.

Better views of Saturn’s southern hemisphere in the coming years should enable astronomers to observe more details of the strange occurrence, giving them a better chance to solve “this intriguing atmospheric mystery,” he said in the statement.

The authors of the study said more observations from Hubble and NASA’s James Webb Space Telescope plus computer model analysis are needed in order to understand how the decagon formed and how long it might exist as well as how it compares to the northern hexagon.

POLL

GLOSSARY

• decagon: a 2D polygon with 10 sides
• Hubble telescope: a large space based observatory orbiting above Earth’s atmosphere. The Hubble takes incredibly clear images of space, reaching billions of light years away into deep space to show galaxies forming. The Hubble has been credited for discovering dark energy and helped to locate moons around Pluto
• jet stream: fast-flowing bands of atmospheric winds generated by the planet’s internal heat
• Outer Planet Atmospheres Legacy: a Hubble initiative to study the atmospheres of the outer giant planets of the solar system each year: Jupiter, Saturn, Uranus, and Neptune
• polygons: flat, 2D shapes made of straight line segments that close to form a loop

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QUICK QUIZ
1. In what ways is the decagon on Saturn’s south pole different to the hexagon on its north pole?
2. How did scientists discover the decagon?
3. When did they first notice the strange formation?
4. Which planet has cyclones that appear in polygonal shapes?
5. When was the hexagon on Saturn’s north pole discovered?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Name the decagon
What name would you give the decagon? Think of a really special name and write a very convincing paragraph. Your purpose is to convince NASA to give it the name you have chosen.

Time: Spend at least 15 minutes on this activity
Curriculum Links: English

2. Extension
What do you think caused the decagon to form? Use information from the story to create a diagram or infographic about this question.

Time: Spend at least 30 minutes on this activity
Curriculum Links: English, Science

VCOP ACTIVITY
To sum it up
After reading the article, use your comprehension skills to summarise in a maximum of three sentences what the article is about.

Think about:

• What is the main topic or idea?
• What is an important or interesting fact?
• Who was involved (people or places)?

Use your VCOP skills to re-read your summary to make sure it is clear, specific and well punctuated.