Saturn’s Death Star-Looking Moon May Have Vast Underground Ocean

This handout image released on February 7, 2024 by Animea Studio - Observatoire de Paris - PSL, IMCCE - shows an artist's impression of the 400-km diameter Mimas, one of Saturn’s small moons. (Photo by Frederic Durillon / Animea Studio | Observatoire de Paris - PSL, IMCCE / AFP)
This handout image released on February 7, 2024 by Animea Studio - Observatoire de Paris - PSL, IMCCE - shows an artist's impression of the 400-km diameter Mimas, one of Saturn’s small moons. (Photo by Frederic Durillon / Animea Studio | Observatoire de Paris - PSL, IMCCE / AFP)
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Saturn’s Death Star-Looking Moon May Have Vast Underground Ocean

This handout image released on February 7, 2024 by Animea Studio - Observatoire de Paris - PSL, IMCCE - shows an artist's impression of the 400-km diameter Mimas, one of Saturn’s small moons. (Photo by Frederic Durillon / Animea Studio | Observatoire de Paris - PSL, IMCCE / AFP)
This handout image released on February 7, 2024 by Animea Studio - Observatoire de Paris - PSL, IMCCE - shows an artist's impression of the 400-km diameter Mimas, one of Saturn’s small moons. (Photo by Frederic Durillon / Animea Studio | Observatoire de Paris - PSL, IMCCE / AFP)

Astronomers have found the best evidence yet of a vast, young ocean beneath the icy exterior of Saturn’s Death Star lookalike mini moon.

The French-led team analyzed changes in Mimas’ orbit and rotation and reported Wednesday that a hidden ocean 12 to 18 miles (20 to 30 kilometers) beneath the frozen crust was more likely than an elongated rocky core. The scientists based their findings on observations by NASA’s Cassini spacecraft, which observed Saturn and its more than 140 moons for more than a decade before diving through the ringed planet's atmosphere in 2017 and burning up.

Barely 250 miles (400 kilometers) in diameter, the heavily cratered moon lacks the fractures and geysers — typical signs of subsurface activity — of Saturn’s Enceladus and Jupiter’s Europa.

“Mimas was probably the most unlikely place to look for a global ocean — and liquid water more generally,” co-author Valery Lainey of the Paris Observatory said in an email. “So that looks like a potential habitable world. But nobody knows how much time is needed for life to arise.”

Results were published in the journal Nature.

The ocean is believed to fill half of Mimas’ volume, according to Lainey. Yet it represents only 1.2% to 1.4% of Earth’s oceans given the moon’s petite size. Despite being so small, Mimas boasts the second largest impact crater of any moon in the solar system — the reason it's compared to the fictional Death Star space station in “Star Wars.”

“The idea that relatively small, icy moons can harbor young oceans is inspiring,” SETI Institute’s Matija Cuk and Southwest Research Institute’s Alyssa Rose Rhoden wrote in an accompanying editorial. They were not part of the study.

Believed between 5 million and 15 million years old, too young to mark the moon's surface, this subterranean ocean would have an overall temperature right around freezing, according to Lainey. But at the seafloor, he said the water temperature could be much warmer.

Co-author Nick Cooper of Queen Mary University of London said the existence of a “remarkably young” ocean of liquid water makes Mimas a prime candidate for studying the origin of life.

Discovered in 1789 by English astronomer William Herschel, Mimas is named after a giant in Greek mythology.



Greece's 'Instagram Island' Santorini nears Saturation Point

Tourists queue as they wait to take a picture from one of the balconies. Aris Oikonomou / AFP
Tourists queue as they wait to take a picture from one of the balconies. Aris Oikonomou / AFP
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Greece's 'Instagram Island' Santorini nears Saturation Point

Tourists queue as they wait to take a picture from one of the balconies. Aris Oikonomou / AFP
Tourists queue as they wait to take a picture from one of the balconies. Aris Oikonomou / AFP

One of the most enduring images of Greece's summer travel brand is the world-famous sunset on Santorini Island, framed by sea-blue church domes on a jagged cliff high above a volcanic caldera.
This scene has inspired millions of fridge magnets, posters, and souvenirs -- and now the queue to reach the viewing spot in the clifftop village of Oia can take more than 20 minutes, said AFP.
Santorini is a key stopover of the Greek cruise experience. But with parts of the island nearing saturation, officials are considering restrictions.
Of the record 32.7 million people who visited Greece last year, around 3.4 million, or one in 10, went to the island of just 15,500 residents.
"We need to set limits if we don't want to sink under overtourism," Santorini mayor Nikos Zorzos told AFP.
"There must not be a single extra bed... whether in the large hotels or Airbnb rentals."
As the sun set behind the horizon in Oia, thousands raised their phones to the sky to capture the moment, followed by scattered applause.
For canny entrepreneurs, the Cycladic island's famous sunset can be a cash cow.
One company advertised more than 50 "flying dresses", which have long flowing trains, for up to 370 euros ($401), on posters around Oia for anyone who wishes to "feel like a Greek goddess" or spruce up selfies.
'Respect Oia'
But elsewhere in Oia's narrow streets, residents have put up signs urging visitors to respect their home.
"RESPECT... It's your holiday... but it's our home," read a purple sign from the Save Oia group.
Shaped by a volcanic eruption 3,600 years ago, Santorini's landscape is "unique", the mayor said, and "should not be harmed by new infrastructure".
Around a fifth of the island is currently occupied by buildings.
At the edge of the cliff, a myriad of swimming pools and jacuzzis highlight Santorini is also a pricey destination.
In 2023, 800 cruise ships brought some 1.3 million passengers, according to the Hellenic Ports Association.
Cruise ships "do a lot of harm to the island", said Chantal Metakides, a Belgian resident of Santorini for 26 years.
"When there are eight or nine ships pumping out smoke, you can see the layer of pollution in the caldera," she said.
Cruise ship limits
In June, Prime Minister Kyriakos Mitsotakis floated the possibility of capping cruise ship arrivals to Greece's most popular islands.
"I think we'll do it next year," he told Bloomberg, noting that Santorini and tourist magnet Mykonos "are clearly suffering".
"There are people spending a lot of money to be on Santorini and they don’t want the island to be swamped," said the pro-business conservative leader, who was re-elected to a second four-year term last year.
In an AFP interview, Tourism Minister Olga Kefalogianni echoed this sentiment and said: "We must set quotas because it's impossible for an island such as Santorini... to have five cruise ships arriving at the same time."
Local officials have set a limit of 8,000 cruise boat passengers per day from next year.
But not all local operators agree.
Antonis Pagonis, head of Santorini's hoteliers association, believes better visitor flow management is part of the solution.
"It is not possible to have (on) a Monday, for example, 20 to 25,000 guests from the cruise ships, and the next day zero," he said.
Pagonis also argued that most of the congestion only affects parts of the island like the capital, Fira.
In the south of the island, the volcanic sand beaches are less crowded, even though it is high season in July.
'I'm in Türkiye
The modern tourism industry has also changed visitor behavior.
"I listened (to) people making a FaceTime call with the family, saying 'I'm in Türkiye," smiled tourist guide Kostas Sakavaras.
"They think that the church over there is a mosque because yesterday they were in Türkiye."
The veteran guide said the average tourist coming to the island has changed.
"Instagram has defined the way people choose the places to visit," he said, explaining everybody wants the perfect Instagram photo to confirm their expectations.