Our home planet only has one moon, and it is the fifth-largest moon in the Solar System. Sadly, our moon is the only one that doesn’t have a proper name, and we just call it the Moon.

Even though it doesn’t have a special name, it is alluring in a unique way. It has captivated humanity for millennia, serving as a figure of natural wonder and celestial intrigue. Furthermore, its proximity makes it a celestial muse for stargazers worldwide.

In this article, we will delve into the multifaceted facets of our lunar companion, touching upon its physical characteristics and its continued relevance in the field of space exploration.

The Overview Attributes of the Moon

Do you know we have a pretty big moon? Comparatively, if Earth is the size of a nickel, the moon’s size is equivalent to a coffee bean. The Moon’s diameter is more than one-fourth of Earth’s (about 3,500 km), and it is a little bit smaller than Mercury but larger than Pluto.

On the other hand, its gravity is one-sixth of Earth’s and half of Mars. So if you were to jump on the Moon, you could jump about six times higher than you can on Earth. However, the gravitational field of the Moon is not uniform. This anomaly is caused by a different mass concentration of the moon’s surface (mascon).

Fact: A “mascon” is a region on the surface of a celestial body, like a planet or moon, where there is a concentration of mass that causes gravitational anomalies. These anomalies can affect spacecraft orbits and are often associated with large impact basins or volcanic features. Understanding mascons is important for space missions and orbital calculations.

The Moon lacks a substantial atmosphere, but it does have an exosphere which is an extremely thin and tenuous layer of gas. Unfortunately, it’s not breathable and wouldn’t support human life.

In addition, the Moon’s lacking atmosphere also caused the temperature to sway to the extreme. On the side facing the sun, it can reach temperatures of up to 127 degrees Celsius (260 degrees Fahrenheit), while on the dark side, temperatures can drop to as low as -173 degrees Celsius (-280 degrees Fahrenheit).

Just like Earth, the Moon also experiences quakes, and they were first discovered by Apollo astronauts. However, the moonquakes are weaker than earthquakes. The moonquakes are caused by the gravitational interaction with Earth and the cooling and contraction of the Moon’s interior.

The Moon’s Mysterious Surface

It was speculated that our moon came into existence approximately 4.5 billion years ago following a cataclysmic collision between Earth and a Mars-sized object. This caused a huge chunk of Earth ejected into space. Eventually, the ejected debris merged through gravitational force, and formed the Moon as we know it today.

Over eons, its surface has borne witness to meteoric bombardment, volcanic activity, and the gradual erosion of time. Its topography exhibits diverse features, ranging from towering mountains and deep valleys to smooth plains and the indelible mark of countless meteoritic impacts, evident in its cratered surface.

As you look at the Moon, you may have noticed the dark grey patches on its surface. These grey patches are called “Maria” which is Latin for seas (singular Mare). Maria is formed through volcanic activity on the Moon during its younger years. The iconic Apollo 11 landed at the edge of Mare Tranquilitatis.

Beyond Apollo: The Next Frontier of Lunar Exploration

The Apollo program was a historic series of missions conducted by NASA between 1961 and 1972. Its goal was to land humans on the Moon and bring them safely back to Earth. Another significant goal of the Apollo program was to gather scientific data about the Moon’s geology and to conduct experiments in its low-gravity environment.

The Iconic Apollo 11

In July 1969, Apollo 11 crews Neil Armstrong and Buzz Aldrin set foot on the Moon for the first time, while Michael Collins orbited above in the command module. The astronauts spent approximately 2 hours and 15 minutes conducting experiments, collecting samples, and taking photographs on the lunar surface. Since then, there have been more five lunar landings through the Apollo program until 1972.

Apollo 14

In February 1971, Apollo 14 safely landed at Fra Mauro Highland sending out the 2nd batch of astronauts Alan Shepard and Edgar Mitchell to explore the lunar geology in that area. This site was selected because it was believed to contain rocks that had been ejected from the Imbrium Basin, providing scientists with the opportunity to study ancient lunar material [1].

Fact: The Imbrium Basin is one of the largest impact basins on the Moon, formed about 3.8 billion years ago by a massive asteroid or meteoroid impact. It has a diameter of approximately 1,100 kilometers (680 miles) and is characterized by concentric rings and a central peak complex. This impact basin played a significant role in the creation of lunar maria (dark plains) on the Moon and serves as a benchmark for dating other lunar geological features based on crater density. The Apollo 15 mission explored the region near Imbrium, conducting geological studies in this area. The basin’s formation ejected debris, including rocks and regolith, across the lunar surface. Overall, Imbrium is a key feature in understanding the Moon’s geological history and impact processes.

Plants Grow in Lunar Soil

For the first time after 50 years of bringing back the samples from the lunar surface, scientists successfully grow plants using lunar soil. The hardy and well-studied Arabidopsis thaliana managed to grow in poor nutrient lunar regolith [2]. This gives hope for future lunar missions, where astronauts can grow their food at the lunar post and extend their stay on the moon to do research.

Fact: Lunar regolith is primarily composed of small rock fragments and dust. These materials are made up of various minerals, including basalt, anorthosite, and breccia, which are the result of ancient volcanic activity and impact events on the Moon

Recent Lunar Missions

Now NASA is focusing on the Artemis lunar program, and its primary objective is to send out the first woman to walk on the Moon. Another big aim of the Artemis program is to build an outpost to serve as a staging point for lunar missions and as a platform for future deep-space missions.

Artemis I was launched on November 16, 2022. Its missions were to orbit the moon, and flight test the integrated Orion spacecraft with Space Launch System (SLS) rocket for the first time.

Recently on August 23, 2023, the Chandrayaan-3 lander and rover safely landed near the south pole of the Moon. This is the first time, human has reached the Moon’s South Pole territory [3]. The objective is to study the material characteristics of the Moon’s surface in the region.

The Moon’s South Pole Exploration

Chandrayaan-3 is the subsequent mission after Chandrayan-2, in which the lander has malfunctioned during the landing process. One of the most significant findings of Chandrayaan-1 was the discovery of water presence on the Moon’s surface. The Moon Impact Probe detected water molecules when it impacted near the lunar South Pole, and this discovery had important implications for future lunar exploration and the potential for water resource utilization.

The Moon is indeed a fascinating celestial body with a rich history of exploration and scientific discovery. To recap this article, here’s a summary of the key points:

Overview Attributes of the Moon:

• The Moon is the fifth largest moon in the Solar System and has no official name.
• It is about one-fourth the diameter of Earth, with one-sixth of Earth’s gravity.
• The Moon has an extremely thin exosphere but lacks a substantial atmosphere, making it inhospitable for human life.
• Temperatures on the Moon can range from extremely hot on the sunlit side to frigid on the dark side.
• Moonquakes, caused by gravitational interactions with Earth and cooling of the Moon’s interior, are weaker than earthquakes.

The Moon’s Mysterious Surface:

• The Moon likely formed around 4.5 billion years ago from debris ejected during a collision between Earth and a Mars-sized object.
• The meteoric impacts, volcanic activity, and erosion had shaped the Moon’s surface.
• “Maria” (Latin for seas) are dark, flat plains formed by volcanic activity.
• The Apollo 11 mission famously landed on the edge of Mare Tranquilitatis.

Beyond Apollo: The Next Frontier of Lunar Exploration:

• The Apollo program (1961-1972) successfully landed humans on the Moon and conducted experiments.
• Apollo 11, with Neil Armstrong and Buzz Aldrin, was the first successful lunar landing in 1969.
• The program included six lunar landings in total.
• Apollo 14 explored the Fra Mauro highlands for ancient lunar material.
• Scientists have successfully grown plants in lunar soil (regolith), a promising development for future lunar missions.
• NASA’s Artemis program aims to send the first woman to the Moon and establish an outpost for lunar and deep-space missions.
• Artemis I, an uncrewed flight, launched in 2022 to orbit the Moon.
• Chandrayaan-3, an Indian mission, recently landed at the Moon’s South Pole, aiming to study the Moon’s characteristics and its water existence.

References

[1]        Schultz, P. H., & Crawford, D. A. (2016). Origin and implications of non-radial Imbrium Sculpture on the Moon. Nature, 535(7612), 391–394. doi:10.1038/nature18278 

[2]        Paul, A., Elardo, S. M., & Ferl, R. (2022). Plants grown in Apollo lunar regolith present stress-associated transcriptomes that inform prospects for lunar exploration. Communications Biology, 5(1), 1-9. https://doi.org/10.1038/s42003-022-03334-8

[3]        Kumar, Sanjay (23 August 2023). “India makes history by landing spacecraft near Moon’s south pole”. Science.org.