“Jupiter and His Moons” by Martina Van Beneden

February 26, 2019.

Everyone knows planet Jupiter. That large planet with a big red spot on it, the biggest planet in our solar system. Jupiter is made entirely of gas, specifically hydrogen and helium with a mix of lighter gases. The mass of this enormous planet is two and a half times that of all the other planets in our solar system combined and even one thousandth that of our sun. Now, we’re all familiar with our little moon, she’s a beautiful satellite that orbits us 24/7. She’s our natural and permanent satellite. Earth only has 1 moon. Jupiter has 79 known moons! This article is going to discuss just a few of them, what they’re made of, how large they are and even if they can harbor extraterrestrial life. 

 The four largest moons of Jupiter are part of the Galilean group. Of these, there is Europa, the smallest of the four. Europa is 3,122.6 km in diameter and takes approximately 3.55 days to orbit Jupiter. The surface temperature on this little satellite is -171°C. This moon even possesses water and with the warm interior, it is believed that Europa could host life. People have hypothesized the possibility of humans capability to survive on Europa, it’s a very, very low possibility. There are noticeable reddishbrown streaks scattered across the satellite that is believed to be sea salt full of radiation. To survive on Europa, humans would need extremely powerful radiation shielding. She wouldn’t be a pleasant place to colonize although Europa is interesting and may have extraterrestrial life hidden beneath her surface. 

 Up next, Ganymede. Ganymede is Jupiter’s largest moon and even the largest moon in the solar system. It’s 5,268 km in diameter and has an orbital period of 172 hours. A common theory about how the formation of this moon came to be is that it formed from some accretion from a disk of gas that was surrounding Jupiter shortly after its formation. It’s made from silicate rock and water ice and several layers. Ganymede happens to be 8% larger than planet Mercury and if it weren’t orbiting Jupiter, this satellite could even be considered a dwarf planet. Ganymede is a strange place, it’s the only moon known to possess a magnetic field which is thought to be generated through its core, its core is composed of metallic iron and iron sulfide which in turn, is surrounded by an icy crust and rock. Like Europa, Ganymede is believed to consist of a subsurface ocean with possibilities of life living inside of there. There are plans in the work of traveling to the large, mysterious moon in hopes to solve many unanswered questions about its interior. 

Io, the fourth largest of Jupiter’s Galilean group. This moon has the most volcanic activity and the least amount of water out of any object in the entire solar system. Io has hundreds of volcanoes that erupt with lava miles high and are so powerful, they can be seen from Earth with large telescopes. Io is only a small bit larger than Earths moon, so not the smallest out there. This satellite happens to be tidal locked, it rotates once on its axis every 1.8 Earth days and completes one orbit of Jupiter. Because of this, the same side of Io is constantly facing Jupiter. Io could not support life but that’s not to say it isn’t harboring some form of life we haven’t heard of or have yet to discover. A few spacecrafts have studied Io during flybys capturing beautiful images of this dangerous moon. 

 Last of the Galilean group is Callisto. Its radius is 1,498 mi and has an orbital period of 17 days. Callisto isn’t known to be geologically active but is believed to have a salty ocean inside. Like Io, Callisto is tidal locked. The same side is always facing Jupiter. This moon is completely covered with lots of craters, though the ocean within is believed to lay 155 miles below the surface. The ocean Inside Callisto has allowed this dead moon to be placed on a list of places possibly capable of holding life. Jupiter’s second largest moon is composed of rock and ice and would be considered a “boring” moon, she has no activity, no volcanoes. Just a potential ocean. This satellite is not one with lots to see. 

To finish, Jupiter has multiple moons. To be exact, 79. 53 are all with names and the other 26 have yet to receive one. The four that were covered in this article all belonged to the Galilean group, Jupiter’s largest moons. They are all unique and pose various amounts of questions. More is being researched on each one hoping to find more within their surfaces. They are special and beautiful and mysterious. Soon, these moons will hopefully give us more insight about their surface, materials and if life could exist within. 


Sources: NASA.gov