Introduction

Japan’s lunar mission, SLIM (Smart Lander for Investigating Moon) landed upside down on the moon on January 20, 2024. While making its descent, it suffered an engine malfunction that caused it to become unstable. Fortunately, the onboard computer managed to keep the spacecraft under control until landing, after which it flipped over. 

"The pinpoint landing was achieved (with an) accuracy of less than 10 meters, and probably about 3 to 4 meters (10 to 13 feet)," an official for JAXA told NBS News later. "We believe that this is a great achievement for future exploration." 

The spacecraft being upside down couldn’t charge its solar panels, which were on top of it causing it to shut down. However, a few days later some sunlight managed to make its way onto the spacecraft’s solar panels due to the shift in lighting conditions. Even though the spacecraft was upside down, the mission team was able to get data and images from it (They had to use photo editing to get the images right side up).  SLIM discovered possible evidence about the origins of the moon. Using technology that compares Moon rocks to Earth rocks, scientists say that it's likely the moon came from Earth. 

What We Know So Far

Today most scientists agree that the Moon came from the Earth. There is a theory called the Giant Impact Origin Hypothesis that says that 4.5 billion years ago, before Earth had any life, our solar system was mass chaos. Planets would crash into each other, spraying smaller debris across towards other planets. Earth was seemingly in the middle of it, then one day a Mars-sized planet which scientists today call Theia smashed into Earth (it is still debated if Earth hit Theia or Theia hit Earth). The impact caused a massive explosion that ejected debris. Even though Earth survived, it still was torn apart. It is believed that the remains of Theia and some rubble from the destruction of Earth merged, creating our moon. 

Disagreements: Even though most people in the science community largely believe this theory, not everyone is on board with this idea. Some scientists argue that we don’t have enough evidence for this theory. 

Two main alternative ideas have emerged as a result: The first one is called the Fission theory, which was proposed by George Howard Darwin, the son of the famous scientist/theorist Charles Darwin, in 1878. The Fission theory states that during the early solar system, Earth was spinning at such an astonishing rate that a large part of it broke off. This large chunk of Earth formed the Moon. This theory however has been criticized by many experts because if it did happen, the material that emerged from our planet wouldn’t just be captured into Earth's orbit it would either go crashing back down or be captured by our Sun and go into an orbit around it. 

The second theory dubbed the Capture Theory was around for years, but it was primarily brought to attention by British physicist and planetary scientist Michael Woolfson. Woolfson argued that the Moon was a small planet or Moon that was kicked out of its orbit by a larger planet and it was captured by Earth's gravity, which resulted in it starting to orbit Earth. However, this theory has also been questioned by scientists because there simply isn’t enough evidence to prove this theory correct. 

The Answer: Even today we don’t have a true answer for how we got our moon. We have the evidence to support all of the three main theories, and the evidence that goes against it as well. Scientists hope that more advanced robotic spacecraft like SLIM and NASA’s Artemis program to send humans back to the moon can help us better understand the true origin of the Moon.               

Sources: 

Vanderbilt University

NPR

NASA.gov