NEW YORK – Volcanoes were erupting on the mysterious far side of the moon billions of years ago, just like on the side we can see, new research confirms.

Researchers analyzed lunar soil brought back by China’s Chang’e-6, the first spacecraft to return with a pile of rocks and soil from the little-explored far side.

Two separate teams found fragments of volcanic rock that are about 2.8 billion years old. One piece was even older, dating back 4.2 billion years.

“It’s very important to get a sample from this area because it’s an area that we don’t have data for otherwise,” said Christopher Hamilton, an expert on planetary volcanoes at the University of Arizona who was not involved in the research.

Scientists know there were active volcanoes on the near side, the side of the Moon seen from Earth, dating back to a similar time frame. Previous studies, including data from NASA’s Lunar Reconnaissance Orbiter, have suggested that the far side may also have a volcanic past. The first samples from that region facing far from Earth confirm an active history.

The results were published Friday in the journals Nature and Science.

China has launched several spacecraft to the moon. In 2020, the Chang’e-5 spacecraft returned lunar rocks from the near side, the first since those collected by NASA Apollo astronauts and Soviet Union spacecraft in the 1970s. The Chang’e-4 spacecraft became the first to visited the far side of the moon in 2019.

The far side of the moon is cratered and has fewer of the flat, dark plains of the near side carved by lava flows. Why the two halves are so different remains a mystery, said study co-author Qiu-Li Li of the Chinese Academy of Sciences.

Li said the new findings reveal more than 1 billion years of volcanic eruptions on the far side of the moon. Future research will determine how the activity lasted so long.