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Although the world is full of unlimited mysteries, one thing that keeps on delivering new discoveries is the moon. 12 men have walked on the moon, as the previous human-led lunar expedition occurred in 1972, but this doesn't mean scientists have stopped trying to learn more about our closest neighbour.
Nowadays, governments utilize crewless expeditions to gather more data on the moon. China's Chang'e-4 unearthed something truly spectacular while exploring the moon's unseen side - a place no human has ever walked before!

This section of outer space has been unseen for the most part of human history, so it comes as no surprise that it's something scientists have never explored before.
The Space Race
There's no talking about exciting discoveries on the moon without considering why researchers and explorers bother with landing in the first place. Moon landings can be traced to what is called the Space Race, a competitive time between the United States and the Soviet Union to see who could get to space first.
When it launched the first manufactured device to the moon, the USSR won in 1959. But many people argue the USA did it better, dispatching a crew to land and even walk on the moon in 1969.

Since then, astronauts had never journeyed to the moon, but relied on machines and other devices to do it for them while they analyzed the discoveries.
China is Extremely Focused on Space Discoveries
Nowadays, uncrewed missions are organized to unearth several things on the moon. Among the steadfast countries undertaking this research is China, through its CNSA. China is sending uncrewed crafts to the moon, a project included in the Chinese Lunar Expedition, which comprises four phases.
- Reach the lunar orbit.
- Land and rove on the moon.
- Retrieve lunar samples and take the findings to Earth.
- Construct a robotic research station.

The first two phases have been completed through Chang'e 1, Chang'e 2, and Chang'e 3. It might surprise you that Chang'e 4, which we will explore next, was constructed as the reinforcement to the Chang'e 3 ship but later got upgraded to a mission of its own.
What Is Chang'e 4 Anyway?
Chang'e 4 is included in the Lunar Exploration Program's phase two. Like many others, the soft landing ushered in notable findings.
The robotic spacecraft mission was a customary expedition. But the rover of Chang'e 4 mission is the first to go to this part, which made to a discovery we had never seen previously.

After all these years humanity is finally back to exploring its nearest neighbour and it had something remarkable hidden in plain sight for us to find. What could that be?
Chang’e 4 is Launched for a New Purpose
Although Chang'e 4 was constructed in case of problems with Chang'e 3, it has become even more significant in the CNSA's discoveries. Chang'e 3 attained the foremost Chinese spacecraft that reached the moon, leading scientists to redesign 4 for new purposes.
Chang'e 4 consists of a lander, relay satellite, and rover. After this, they sent the robot into space on the 7th of December, 2018.

The renewed aim of Chang'e 4 was to discover what that side of the moon has been hiding all these year and to analyze the comprising components of that area, a region no other expedition has ever reached before. This is what caused the unexpected finding.
A Landing for the History Books
Chang'e 4 finally got to the far region on the 7th of December, 2018. It signified the first space mission in that distant area.
This achievement is one of the most notable historical happenings in space probes. After the success of Chang'e 3, Chang'e 4 was modified according to new specifications and scientific discoveries. And yet, it had a mission of its own.

Chang'e 4 was to explore the Aitken Basin, a huge crater left by some ancient collision millions of years ago. With a diameter of 13 km, this crater offers loads of data and, hopefully, material to explore and gain new information about the moon.
What’s So Great About the Far Side of the Moon Anyways?
When you look at the sky, only one section of the moon is visible because that's the part facing our planet. It's not surprising that no one explored it prior to Chang'e 4, as that section is not visible to us.
The gravitational pull is the reason why only a specific section of the moon faces us. The moon features an orbit surrounding the Earth, which has remained the same for several billion years.

Because of this, it is patterned based on Earth's orbit. This causes the moon to turn on its axis and encircle the Earth every four weeks while showing us a particular section.
What We Knew About the Far Side Before Chang’e 4
Don't be mistaken! Space researchers had viewed that section of the moon through satellites and orbital photographs, but the exterior and its components remained unknown to them.
That side of the moon was unexplored territory, causing us to believe that it somehow differs from the part that is facing the Earth.

This is the reason why it was exhilarating for the researchers to finally be able to take a look at what was actually happening on that side of the moon.
Why Did We Never Check Out the Far Side?
The moon is round, and it's only natural that the opposite side exists, so why did no one send a spaceship there before 2018? Well, it's hard to maintain communication with the crew in that specific area because the moon blocks radio contact.
The space craft might get isolated from humankind, being lost forever on the other side of the moon. But, Chang'e 4 produced a solution to solve this, using a relay satellite instead.

Even with its in-built relay satellite, making contact between Chang'e 4 and the base station takes a long time. Also, any other spaceship going to this side should choose its position carefully to prevent cutting off radio contact.
What Happened After Landing?
Chang'e 4 operation was a success - having performed the landing, the team of scientists was fascinated by the space view from the moon's far section. The spacecraft settled on the Von Karman crater in the Aitken basin that covers up to one-quarter of the moon's surface.
Once it reached the destination, the in-built Yutu-2 rover was sent out. China designed it to keep tabs on the moon's exterior, take photographs, and transfer the files to the Earth station.

Researchers assessed all the pictures, spending quite some time unearthing the rare findings.
Research on the Moon’s Other Side
With Chang’e 4 now on the moon, scientists could conduct their research through Yutu-2. While being on the other side of our moon, the rover shut down twice daily. Once was midday to guard itself against the sun, and the additional time was at the end of the day.
Whenever the rover was sleeping, this was the ideal time for scientists to check the photos sent for any new findings. On the downside, they only found lunar regolith (dust) covering the moon.

But this status quo did not last long. The image shows a few findings that have baffled all the scientists - and they still can't say what it truly is!
Strange Findings on the 28th of July
Scientists must have thought that the 28th of July, 2019, would be like every other day on the opposite side of the moon. The rover took pictures as usual and sent them back to the researchers.
But on this day, one of the researchers found something different in the images sent, as Yutu-2 shut down in the middle of the day.

He had never seen this before, so it was only right to take another look.
Weird Reflections
On that day, the handler who discovered the crater and shadows on the other side of the moon was Yu Tianyi. When reviewing the data he received, he noticed a tiny hole.
In that crater, there was a gеl-like substance with a weird color. It stood out well from the surroundings and had shiny reflections, which they noticed first.

To find something like that on the moon was mind-boggling and left all the scientists speechless. It was unlike anything they've seen on the moon before - this discovery promised to be one of the most fascinating space events of the year.
Update the Mission
Once Yu Tianyi saw the weird gel substance in the crater on the other side of the moon, he informed the other scientists immediately.
This was a discovery that no one could ignore, even if it weren’t clear what they had just unearthed.

So, the mission plans were updated. Instead of just going around and taking pictures, the Yutu-2 was used to examine the crater and its contents.
Informing the World
The scientists didn’t keep this abnormal finding to themselves. Instead, the Chinese government informed the world through an official announcement on Our Space in their language.
It was also found in the People’s Daily newspaper in China.

When the world found out, different types of guesses were made, and readers were curious about what that substance could be and what it meant for space exploration.
Making Guesses
Note that the scientists made an official announcement without even figuring out what it was. After the public statement, many guesses and speculations were made to determine the substance.
The scientists and even the public were also making guesses as to what the substance could be. There were quite a few theories, ranging from impossible to more likely explanations involving other celestial bodies.

Even People’s Daily was engaging the public to find out their opinion on the topic!
What Could It Be?
There were many ideas about the gel-like substance since many people were speculating. But it turns out it wasn’t a gel (or at least that's one of the main theories most scientists believe to be true).
While it was glittering like a gel, a possible explanation is that it was bright melted glass left by a meteorite after it hit the moon. After all, it was found inside the moon crater.

This explanation became widely accepted by scientists on a global scale, but there is still no actual proof that the gel-like substance is of that origin. Some geologists think it could be something different!
What Type of Glass Could It Be?
Although there was very little information to use in figuring out what the substance was, researchers believed that the glass was of volcanic origin.
This claim was made by the VP of the Royal Astronomical Society in the UK and a planetary scientist working at Open University, Mahesh Anand.

The significance of the finding on the other side of the moon is that there could be another type of material beneath the surface since glass is covering it up. It would be even more critical if the materials were ice or water-related.
Maybe a Meteor Hit the Moon
So now scientists wonder, ‘Did a meteor hit the moon?’ Water Freeman, a physicist at Syracuse University, believed that the glass was formed because of the incredible force created when the meteor hit the moon.
According to him, this situation caused the dust on the moon to turn into glass. The moon is different from Earth, especially since various happenings create the geology we see today.

Some meteorite greatly impacted its surface, leaving a few surprises for geologists to find. Scientists had no idea that the monotonous moon surface had so many exciting things lying around!
A Meteorite to the Moon Like a Nuke to Earth
Walter Freeman went further to say that the strange glass on the moon could be compared to the effect of a nuclear bomb on Earth.
The first-ever nuke, which underwent testing in New Mexico, created a glass-like substance after the explosion.

It is called trinitite and was made by the head. The same thing happened when the meteorite hit the moon.
Not the First Weird Stuff on the Moon
While speculating and figuring out what the strange substance on the moon was, scientists found themselves reviewing past missions. After all, they can get some ideas about the gel-like substance by thinking about what they found in the past.
And then experts realized: this isn’t the first time they found something odd on the moon. The last crewed mission resulted in a strange discovery, which will provide insight into Chang’e 4’s mission.

It was definitely not something scientists expected to find on the moon, but on the other hand, there's still so much we don't know about it!
The Moon’s Orange Soil
The last human-crewed mission to the moon was the famous Apollo 17, which took place in 1972. As the astronauts returned to our planet, they discovered something odd in their cargo: orange soil.
One of the astronauts was also a geologist, and he collected a sample of this orange soil from the Shorty Crater. It was taken to Earth for more research by scientists.

Once the astrophysicists figured out what created this spectacular orange soil on the moon, they were even more puzzled.
What Did Apollo 17 Bring Back?
The geologist recorded the findings of the orange soil in photographs, but they were pretty blurry because he couldn’t sit still from all the excitement.
On the bright side, we have a clear and colored image to look at since his commander and another crew member took pictures of the orange soil. But what was this orange soil?

Harrison “Jack” Schmitt, the scientist behind this unique discovery, proved that our moon hasn't always been a silent and deadly neighbour. There has actually been some activity there in the past other than a bunch of astronauts paying a short visit to the moon.
Eruption on the Moon
After NASA investigated the orange soil brought back by the Apollo 17 crew, a fantastic discovery was made. A volcanic eruption caused the orange soil!
Not only this, but the eruption is dated to have happened over four billion years ago! It’s strange enough that a volcano was on the moon billions of years ago.

The orange soil was the remains of a fire fountain (moon volcano) that sprayed molten lava into the sky and then solidified.
China Finds the Answer
With help from the orange soil and other previous lunar discoveries, Chinese scientists finally had an answer to share with the world in August 2020. And, you might have guessed it, too!
The scientists who investigated the data from the rover’s camera and VNIS (Visible and Near-Infrared Spectrometer) agreed that the gel-like substance consisted of rock.

But what did this mean in the bigger picture? The gel-like substance was finally revealing its secrets to the scientists.
What the Gel-Like Substance Was Made Of
In reports, the jelly-like substance was described as an emerald-colored and shiny impact melt breccia. It also had a measurement of 20”x 6”. The design seen could only be caused by glass, which is a common occurrence whenever ii melts, or a volcano erupts.
So, scientists stated that the substance was a breccia. In simpler terms, these are broken pieces of minerals that solidified together.

And it was a result of natural welding caused by an impact on the moon. It was later cemented and combined with lunar regolith.
Previous Apollo Missions
There’s one more surprising fact aside from the volcanic explanation. It was also discovered that the breccia on the opposite side of the moon was similar to a lunar impact melt brought back during other Apollo missions.
Scientists didn’t only focus on the orange soil but another discovery made in past Apollo missions.

This is defined as Sample 70019 and Sample 15466, which were also breccia on the moon found during past expeditions.
Problems with the Conclusion
Although the conclusion from the Chinese scientists is plausible, it isn’t a definite explanation. Unfortunately, the measurements from the rover’s VNIS were captured with poor lighting.
Other factors limited their analysis, making it hard to get a definite answer. But, the chances of the substance being glass caused by a volcanic eruption or impact melt are high.

Still, judging from the photos only it's really hard to tell whether that substance is of gel-like structure or could be made of some sturdy material like glass. This discovery has really baffled the scientific world of the planet Earth!
Lessons Learnt
Although the groundbreaking Chang’e-4 discovery isn’t definite, there are still lessons that the world and space travel community has learned. It was challenging to reach a different area of the moon, and this discovery was one of a kind.
NASA praised the scientists at the CSNA for properly documenting every detail, making it easy for other researchers to understand how they reached their conclusion.

The scientists were quick to react when they noticed the unusual sighting and as the rover should have gone into resting mode at that moment, they decided to investigate more. Their spirit of exploration led to one of the most mysterious scientific discoveries of the decade!
More Lunar Discoveries to Come
Even if space organizations are not sending crewed missions to the moon, they throw their full weight behind uncrewed expeditions. There will always be parts of space, even the moon, that we don’t know about. So, explorations will never end.
With this in mind, you can expect even more lunar discoveries in the future. As technology evolves, many other spaceships like the Chang’e-4 will discover substances and see places we have never seen before.

And who knows, maybe this time we'll finally demystify all the wonderful discoveries that were made on the moon. A new age of moon exploration is already here!