The universe is a vast place. Consider this. Let’s say we believe that the distance to the edge of the observable universe is roughly the same in every direction, which means that the universe is shaped much like a ball. Then the diameter of said ball o’ universe that is observable from Earth is about 93 billion light years across. Which means that it takes light 93 billion years to travel from one end of the universe to the other. Which means that the light we Earthlings can perceive from across the universe took 93 billion years to reach us. WHICH MEANS that when we perceive said light, we are essentially looking 93 billion years into the past.
When contemplating the scale of the universe, I can’t help but think about the certainty (yes, certainty) of life out there in the vast unknown. How many other creatures across the span of the universe sit and stare up at the stars… wondering…. who else is out there? Quite a few I would expect.
But, what about the possibility of life within our own tiny solar system?
There are four large moons that surround the planet Jupiter, aptly named after the Greco-Roman god’s lady loves. Along with 67 other moons, they make up the Galilean satellites.
Io, named after a nymph and priestess of Hera who was seduced by Jupiter and then transformed into a heifer to escape detection, is the closest moon to the planet Jupiter. With over 400 active volcanoes, she is the most geologically active object in the solar system, producing plumes of sulfur that can climb as high as 300 miles.
Ganymede, the largest moon in the solar system (larger than the planet Mercury), takes his name from the beautiful mortal Ganymede of Troy. Ganymede, masculine, beautiful and strong was abducted by Zeus who took the form of an Eagle, snatched up Ganymede, and made him a cup-bearer in Olympus. Ganymede the satellite is the only known moon to generate its own internal magnetic field.
Callisto, the most heavily cratered object in the solar system, is thought to be a long dead world with a surface age of about 4 billion years, making it the oldest landscape in the solar system. Her namesake Kallisto, was a priestess of the virgin moon goddess Artemis. Yet another victim of Zeus’s seduction, Kallisto was ravaged after Zeus tricked her by taking the form of her mistress, Artemis. After breaking her vow of virginity, Kallisto was turned into a bear who was then slain by an enraged Artemis.
Together, these three large moons of Jupiter push and pull the icy satellite that is Europa. Their constant pull, and the pull of Jupiter, creates tidal flexing and therefore heat at the core of Europa, which has led scientists to believe that beneath the 6-20 mile thick layer of ice on the outside, Europa is composed of a liquid ocean that may be twice the volume of Earth’s ocean.
With water comes oxygen… with oxygen comes life. Could this mean that there is a moon within our solar system that has life on it? It’s a possibility that seems so real to some scientists that the Galileo mission, launched in 1989, only flew by Europa without landing on its surface. Why? Because scientists feared potentially crashing into the surface of Europa, breaking through the ice, and possibly harming a fragile ecosystem that is assumed to have had no extraterrestrial contact up to this point.
The next mission to Europa is the European Space Agency’s Jupiter Icy Moon Explorer (JUICE), which is due to launch in 2022 and would therefore reach the Jupiter system in 2030. If successful, JUICE will evaluate Ganymede, Calisto and Europa as potential supporters of life. Who knows, in fifteen years, we may discover the answer to the ultimate question— are we alone?