Jupiter and Her Moons: Our Key to The Cosmos


By Bradley Stockwell

Everyone at some point in their lives (or so I hope) has experienced the wonderful reverence of stargazing. That allure to look upon the heavens and ask ‘what the hell is that?’ seems to be what makes us human; what separates us from the almost nine million other life forms we share this planet with. The night sky has inspired legends, religions and philosophies; our ancestors used it to navigate and mark the passage of seasons and animal migration patterns. But in our present day, the union between us and our big starry-spotted buddy has faded in some sense. Its full glory is now often hidden behind city lights and the petty dramas of our daily lives or the ones we find on television.

While I too am not immune to getting caught up in the rigors of daily life or the latest Doctor Who episode, it’s not too often you’ll find me under a clear night sky without my neck craned upwards. There’s something viscerally exciting to me about seeing the cosmos nude. This is why instead of grabbing a beer and the television remote after a stressful day, I’ll typically still grab that beer but I’ll reach for my telescope instead. While admittedly this may seem like a nerdy pastime, I’m going to try my best to convince you it’s not.

If you’ve ever traveled to a foreign land, the first time feels almost as if you’re visiting an alien planet. Suddenly your perspective of the world increases and you come back home changed. Looking through a telescope for the first time is much the same. I know the first time I saw Jupiter or the magnificent rings of Saturn suddenly our place in the solar system became very real. You can read and study about something all you want, but it’s not until you experience it firsthand that it truly becomes real.

The winter sky is my favorite time for stargazing, primarily because the most important astrological sight to the history of astrophysics and arguably modern science is visible: Jupiter and her moons. This sight has been the key to opening up the cosmos and has been crucial in defining our universe. The best thing is it doesn’t require a high-powered telescope to see it either. In fact I recommend using an entry-level telescope (no more than $150) to see Jupiter and her moons much like the great Galileo Galilei did for the first time on January 7, 1610.

When Galileo first pointed his homemade telescope towards Jupiter, he described seeing a linear arrangement of three fixed stars, two to the east and one to the west, cutting through the center of the planet. However the following night all three stars were to the west. Then three days later one disappeared and six days later a fourth one appeared. At first he was baffled, but then it dawned upon him that these were not stars but were orbiting moons! They were in fact Jupiter’s four largest moons, Io, Europa, Ganymede and Callisto, which now bear his namesake as Galilean moons. The discovery would be the beginning of a great change in science, but it did not come without challenges.

At the time, the discovery was highly controversial. You can even say Galileo was putting his life at risk by proposing it. A planet with smaller orbiting bodies was in direct offense to the longstanding view of the Catholic Church which placed Earth at the center of the universe and all celestial bodies orbiting around it. The church had a long history of burning ‘supposed’ heretics at the stake for challenging this model. But upon further observations by other astronomers, the evidence was irrefutable. The church eventually conceded and accepted a model proposed almost 70 years earlier by the astronomer, Nicolaus Copernicus. The model, which Copernicus waited until he was on his deathbed to present in fear of being labeled as a heretic, placed the sun, not the earth, at the center of the universe. Obviously this model, now called the Copernican model, would continue to be updated, but it would lay the foundation for others like Johannes Kepler, Isaac Newton, William Hershel, Edwin Hubble and Albert Einstein to further define our universe. Galileo’s discovery would help ignite a scientific revolution during The Renaissance and finally break down the cage in which the Catholic Church put scientific research in.

Jupiter and her moons would again make history when the astronomer, Giovanni Domenico Cassini, observed them between 1666 and 1668. He was the first to notice discrepancies in their orbits. To explain these discrepancies, he theorized that light coming from them must have a finite speed. Shortly after, another astronomer, Ole Romer, took this concept further when he realized that indeed the time it took for Io, the innermost Galilean moon, to orbit was shorter when Earth was closer to Jupiter and longer when Earth was farther away. From these observations, Romer was able to calculate the speed of light; approximately 186,000 miles per second. Putting a speed limit on light would forever change how we view the universe for when we peer into the cosmos we now know we are looking back in time! In fact we can now look at light as far back as the beginning of the universe. A telescope is not only a ship with which to sail the cosmos but also time.

In addition to aiding our view of the universe, Europa, the second innermost Galilean moon, may be a likely candidate for harboring alien life! This moon is covered in a thick layer of ice made of water. Because of heat generated from the contraction and expansion of the moon by Jupiter’s powerful gravitational force, many astronomers believe there is liquid water below the surface which could possibly host microbial life.

Jupiter and her moons is but one of the many wonders awaiting your gazing eyes. Although I am not religious, spying through my telescope is the closest thing I have to prayer. It gives me a better vantage point on life and puts things, or should I say the earth, into a humble perspective. While I’m certain life exists somewhere else in the universe, the right conditions to produce it are rare; and intelligent life, extremely rare. In fact from research and astronomical observations alone, it’s not a stretch to say that out of the hundreds of billions of other planets in the galaxy, Earth may be the only one with advanced life. Granted our galaxy is but one among 350 billion in the observable universe, but this perspective suddenly increases the value of our existence. How lucky are we that the winds of energy that control the cosmos happened to deposit matter in the form of the human race? Regardless of how you believe that came to be, there’s no need for theology to tell you how special your existence actually is. I think if we as humans realized this more, we’d start behaving differently. We’d start looking out for ourselves and this world better because right now as a species we don’t particularly have a universal view on life. It’s rather shortsighted in my opinion. Well until next time, stay curious my friends!



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