What are moon craters and how are they formed?

All of us have seen pictures of Neil Armstrong, the first man on moon, haven’t we? While the images still give us goosebumps, they also guide us through the lunar surface. Now, those of you who have taken a closer look at these snapshots, and did some research on your own, must have definitely observed scattered pit-like features in the background. These are known as lunar craters.  

Astronauts estimate that there are as many as 300,000 craters on the near side of moon, that are not only visible from the Earth but are also spread across more than half a mile. On the far side of moon, there are a greater number of craters, some of which still remain unexplored. Now, the question is, what is a crater, actually? 

Simply put, a crater (often formally known as ‘astrobleme’) is a spherical pit created by the impact of a meteorite or any other similar celestial objects. Interestingly, these bowl-shaped landforms that resemble pits are mainly found along a giant basin known as ‘mare’. It was once thought to be a lunar waterbody. 

Formation of lunar craters 
As you can imagine, moon was an unchartered territory for long. As a result, we didn’t know much about its craters or their formation. However, when astronauts finally landed on moon, they brought back souvenirs, most of which were rock samples. After studying them thoroughly, scientists revealed the much-anticipated reason behind the formation of moon craters. Guess what it was? Volcanic eruption. Yes, just like on Earth, its sole satellite, moon, too has volcanos. They have led to the formation of infinite craters, since almost 4.5 billion years. As it happened, the volcanoes on the moon erupted, causing molten rock to well up. These created huge pools of lava that got deposited in places, creating the craters.  

But wait, are volcanoes the only factor behind the formation of lunar craters? Certainly not. As long as the moon has existed, it has been bombarded by chunks from comets, meteors as well as asteroids, creating the craters as we see today. Surprisingly, their shape has remained unchanged. This is because, in the absence of air or water, the crater edges hardly got eroded. Solar winds, cosmic rays and other dust particles are also said to have contributed to the formation of moon craters.  

What do moon craters look like? 
They are round in shape with circular ridges. A few of them have peaks too, while others have debris scattered all over. The shapes often reveal information about the impactors that created lunar craters. But isn’t it intriguing that all of them have pretty much the same shape despite the fact that the impactors hit the moon’s surface at different speeds, from different directions and angles? Shouldn’t the moon ‘dents’ vary in their shapes if we factor these in? The speed at which impactors rush towards the moon and crash into its surface is so high that their size, direction and angle of striking become irrelevant in influencing the shape of lunar craters.