Where did the moon come from?
Where did we come from?
I love British panel shows. Back in my web radio days, I made a friend that loved the same music I was playing on my show, and when he realized I also had a specific type of humor he suggested to me a British comedian by the name of Dara O’Briain. After watching him do standup I realized that there is a big world of panel shows in British television that are very much my jam when it comes to funny things. O’Briain, also hosted a very fun and informative show called “Dara Ó Briain's Science Club” which opened up a new world to me. Science in the media doesn’t have to be boring. It can be funny! And since you’re associating the information with an emotion maybe this can lead to a world where scientific information can be more widely understood.
Through the now all familiar youtube rabbit holes I ended up watching a show called QI. A very “traditional” looking panel show led by the very friendly Stephen Fry (and later the magnificent Sandi Toksvig) that basically quizzed comedian guests on historical and scientific knowledge. Granted, QI shouldn’t be your reference for 100% accurate knowledge, but you could learn so many things. Such as that there is “no such thing as a fish” or “How to (not) induce labour”. One of the questions that was repeated sometimes over the years in the show was “How many moons does the earth have?”
To my surprise, the answer was never “one”. Depending on what was the latest discovery, or what definition you were using the answer ranged from zero to several thousand! Of course, all of these facts were used mostly to poke fun at the contestants for a laugh. But then it got me thinking. What is the “correct” definition of the moon? And also, where did the moon come from? To my surprise, this last bit is something that scientists are still researching and that’s what we’ll look into this week!
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How do you define a moon?
According to National Geographic, a moon is a celestial object that “orbits a planet or something else that is not a star. Besides planets, moons can circle dwarf planets, large asteroids, and other bodies.”[cite] Moons are held in place by the planet's gravity and follow a path known as an orbit. Moons are typically much smaller than the planets they orbit and can vary in size and shape. Based on this definition, you will logically tell me that the Moon classifies as a moon and you’d be right. And it is generally agreed at the moment of writing that the moon you see every night (most nights) is the only permanent natural satellite of our planet.
HOWEVER, over the years, astronomers have named some other celestial objects as moons, or mini moons. In 2012 researchers from the University of Hawaii published a paper entitled “The population of Natural Earth Satellites”. In this paper, the researchers highlighted that our planet constantly captures and releases small objects. At any given time there is at least 1 object that has a diameter of at least 1 m in diameter and it orbits our planet. The catchy named RH120 has a diameter of 2-3 meters and comes to close proximity to the Earth-Moon system every twenty years. In 2006 it made four earth orbits of about three months each before it was ejected in June 2007.[cite] In 2020 another paper was published talking about the minimoon asteroid named 2020 CD3 (peak naming creativity I know), which stayed in orbit for about 3 years.[cite] So yeah, as it turns out, it is a bit more complicated to answer the question of “How many moons does the earth have?”.
Where did the moon come from?
Now that we established that we could have more than 1 “moons” let’s talk about THE moon. The big disco ball we see at night reflecting sunlight, provoking us to start a party in the sky. How did it get there? We know that billions of years ago our planet was very very different than how it is today. And then it was hit by your aunt. Let me rephrase. It was hit by an object that is about the size of Mars and it was called aunt. But because it would have been ridiculous to call it aunt, scientists gave it the equivalent greek name “Theia” (means divine in greek). From that collision, the moon was formed, although how the exact formation took place is a bit more puzzling. Some theories claim that the moon was formed out of that collision's debris when they merged over months or years.
Here comes the new theory from a recently published paper. The new theory suggests that the moon might have formed mere hours after the collision of the Earth and Theia. This new theory came after a high-resolution simulation that was done by researchers from Durham University, University of Glasgow and NASA. To understand how the moon arrived there, scientists need to take into account many factors such as its mass, its orbit and the composition of the soil. Knowing all these factors they then can come up with different scenarios that could lead to what we see today. You can see the result of their simulation in the video below
What is different about this theory?
One thing that makes this theory different than the others is that it better explains the composition of the moon. Rock samples from the moon, have shown very similar isotopic signatures to Earth’s surface. Scientists can study isotopic signatures to figure out things like the age of rocks, the origins of meteorites, and in this case the composition of the Moon. Previous scenarios stated that Theia only mixed with a little material from the earth and in this case the similarities will be less likely.
We can’t say with certainty that this theory is the correct one, but with more analysis and more data, scientists will be able to compare how their simulations match the real-world conditions. This is fascinating not only because we can find out how the moon came to be, but at the same time we will better understand how we evolved on the planet. Reading this makes me have so many more questions though.
Can we tell where did Theia collide with the earth?
What did Theia look like?
If this never happened, how would life evolve on our planet?
Any more questions that you have after reading this? Read more about the simulations and some statements from the researchers themselves in this article from NASA.
Any more news?
People in academia are constantly coming up with new and exciting things so if you need more to quench your curiosity here are some more headlines.
Moths are more efficient pollinators than bees, shows new research, by University of Sussex
Having camera on during online classes increases social appearance anxiety, which decreases learning of students, by PsyPost
Don’t Forget: What is Hepatitis?
That’s all for this week! I hope that the rest of the week will be calm and rewarding. Did you like this newsletter? If you did you can subscribe to it at the top of the page and why not share it around using this sexy little button here
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Until next week… take care and be kind [=