Ganymede is one of the most fascinating moons out there in the solar system. Ganymede is Jupiters largest moon and in fact the solar system’s largest moon. It’s covered in craters caused by space debris hitting it constantly. Honestly, I don’t want to spoil all the fun facts so let’s jump into the 3 awesome facts!
1. Ganymede has a magnetic field that only a few planets have in the solar system
Credit: NASA
Imagine you’re on Earth and you see a beautiful aurora light up the sky as the colors dance around. Now imagine you’re on a moon that is much smaller and more intimate. Suddenly you see an aurora that mesmerizes you as you look at it through your helmet. A magnetic field is incredibly important and much more than letting us experience auroras. They protect life from the solar winds and energetic particles that slam into the planets and moons. A magnetic field is not as common in the solar system as one might think as well. For example, Mars does not have an active core or magnetic field. Mars is lifeless as far as we know now and not having a magnetic field plays a huge part. The fact that we discovered Ganymede has a magnetic field is inspiring that life can exist on not only planets but perhaps moons. The reason Ganymede has a magnetic field is that of its active iron-nickel-rich core.
2. Ganymede is the largest ocean in the solar system and has 35X more liquid volume than Earth!
Credit: NASA
If you’ve ever seen the ocean or even sailed on it you might have a sense of how large and vast our oceans are. However, the funny thing is that Earth doesn’t have the most water in the solar system. In fact, it doesn’t crack the top three! It lands at number five right below Europa¹. However, Ganymede has an enormous amount of water. It holds 35 ZL (35 billion cubic kilometers) of water vs. Earth’s 1.335 ZL and Europas 2.6ZL. The fascinating part of Ganymede is that it has an ice crust that is 800 km thick. To give you a sense our deepest part of our ocean is only a mere 36 km. You can start to imagine how massive this ocean is on Ganymede. It’s actually one of the top places that might harbor some sort of life.
3. Ganymede has signs of oxygen in its atmosphere and maybe an ionosphere!
Credit: NASA
As we all live and breathe this wonderful air that is essentially our atmosphere. In our solar system there aren’t too many moons that have an atmosphere. Usually, most of it escapes like our Moon for example. The reason it hasn’t escaped is that of Ganymedes magnetic field that keeps it in as best as it can. It’s a thin atmosphere and mostly comprised of oxygen from what scientists have seen and analyzed. So why does Ganymede have oxygen? Well glad you asked, it’s because when the water molecules on Ganymede are split into hydrogen and oxygen from radiation. Hydrogen atomic mass is so light that it just escapes but the oxygen stays around. However, what’s interesting is in the scientific community there is a controversial debate on whether there is an ionosphere on Ganymede. It’s because of the conflicting data scientists have seen from various instruments. The ionosphere on Earth sits above our atmosphere and plays a crucial role in allowing us to communicate through radio waves and reflect back to Earth. Scientists also believe that Ganymede may have an ozone like Earth as well!
Well, I hope you enjoyed this little trip with me on exploring Ganymede. It’s a huge moon that is just under half the size of Earth. It has gigantic oceans that dwarfs ours by 35x and who knows what life may be waiting to be discovered. We still don’t have any recent data on Ganymede but analyzing all the previous data we’ve had since the 70’s.
If you’re interested in reading more about Ganymede then here are a few resources I used as well as you can read: