Six months after the Japanese Hayabusa-2 probe finally reached asteroid Ryugu following a 3.5-year chase through the solar system, the mystery of the 3,000-foot-wide space rock is beginning to unravel.

Once the spacecraft snapped its first high-resolution photos of the asteroid during its approach phase in mid-2018, the mission’s team was able to see clearly what the surface of Ryugu looks like. The most prominent features on the carbon-rich asteroid have now been given official names, the Hayabusa-2 Project announced today on its website.

“Places on the surface of Ryugu have been officially named!” the mission’s team wrote on Twitter.

These names — which were officially approved by the International Astronomical Union (IAU) in December of 2018 — are all inspired from children’s fairy tales and will help scientists refer to key locations on the surface of the asteroid by their official designation rather than by nickname.

“As the appearance of Ryugu gradually became clear during the approach phase in June 2018, we used nicknames amongst the Hayabusa-2 project team to distinguish regions of the terrain,” team members said in a statement.

“However, in order to introduce Ryugu to the world, it is necessary to have names that are internationally recognized rather than nicknames, which can be referred to in scientific papers and other articles.”

Since naming the features of celestial bodies requires a certain procedure — the features to be named are chosen following specific criteria, such as size and their scientific importance — Hayabusa-2 team members sat down with planetary geology experts and eventually came up with 13 locations of scientific interest that they believed merited an official designation.

Dorsa And Fossae And Saxa, Oh My!

The 13 chosen locations on asteroid Ryugu belong to four types of landforms and terrain features, and include craters, dorsa (from the Latin “dorsum,” meaning “peak” or “ridge”), fossae (grooves or trenches, just like the ones seen on Mars), and a new classification of terrain called a “saxum” (plural, “saxa”). This fourth term is also of Latin origin and refers to the many rocks and boulders that populate the surface of the asteroid.

The saxum category of landforms is new in the nomenclature and was specially created for asteroid Ryugu in order to describe its rugged, boulder-strewn terrain, explained the Hayabusa-2 team. The IAU has officially accepted the term, which now describes large boulders with a diameter of at least 1 percent of that of the entire celestial body.

Map of asteroid Ryugu showing the names of its main features.
Map of asteroid Ryugu showing the names of its main features.Featured image credit: JAXA

As the Inquisitr previously reported, the name of asteroid Ryugu — which means “Dragon Palace” in Japanese — was inspired by a folk tale titled “Urashima Taro.” The space rock was named after an undersea castle where a fisherman called Urashima meets the princess Otohime. The main characters of the ancient Japanese tale have now lent their names to the asteroid’s main features — many of which have been designated after people or places from the same story.

Inspired By The Japanese Folk Tale That Named Asteroid Ryugu

For instance, the biggest crater on the surface of Ryugu — originally nicknamed after the Death Star in Star Wars — is now called “Urashima,” while “Otohime” was chosen for the space rock’s largest boulder, found near the south pole.

“Both of these are very important features for deciphering the formation history of Ryugu,” said the Hayabusa-2 team.

The interesting thing about Otohime Saxum, apart from being substantial in size, is that it has a “distinct visible light spectrum that reveals materials and surface conditions that are different from the surrounding areas,” explained the team.

Maps of asteroid Ryugu showing the location of the recently named craters, dorsa, fossae, and saxa.
Map of asteroid Ryugu showing the location of the recently named craters, dorsa, fossae, and saxa.Featured image credit: JAXA

Another important boulder on the space rock’s surface is Ejima Saxum, named after the place where Urashima rescued the turtle that later took him to the Ryugu palace. Meanwhile, the ridge in the middle of the asteroid was named Ryugin Dorsum, after the father of princess Otohime and the ruler of the Dragon Palace.

“A defining feature of Ryugu is that the shape is similar to a spinning top or abacus bead. This shape is the combination of two cones which appear almost circular when seen from the north pole. The ridge where they join was named ‘Ryujin,'” said the Hayabusa-2 team, who noted that the ridge “resembled a dragon coiling around the asteroid or an ouroboros (the image of the serpent or dragon that swallows its own tail).”

In addition, two large grooves found on either side of Otohime Saxum have been dubbed Horai Fossa and Tokoyo Fossa — after the alternative names of the mythical undersea world that houses the Dragon Palace.

Named After International Children’s Tale

Not all the features on asteroid Ryugu have been named after Japanese folk takes. The Cendrillion Crater on the surface of the space rock gets its name from the original French title of the “Cinderella” story. At the same time, one of the asteroid’s craters was named “Brabo” after the hero of a Dutch tale. Last but not least, the Kolobok Crater and the Catafo Saxum were both named after characters in Russian and Cajun folktales.

Aside from the 13 formally recognized names, new photos released by the Japanese Aerospace Exploration Agency (JAXA) also mark the location of the MINERVA-II1 and the MASCOT landing sites. While not officially approved by the IAU, these locations have been nicknamed “Trinitas,” after the birthplace of the goddess Minerva, and “Alice’s Wonderland,” respectively.