Have you ever wondered what may be the purpose of the moon? Well, the moon is the shiny beacon that lights up the night as the sun lights up the day. This amber body is quite shy and doesn't always show itself, but when it does, the moon's brilliance overpowers the darkness. The surface of the moon inspires astronomers around the globe who religiously watch as our incandescent orb passes serenely through its natural cycle, but if you are an avid planet observer you will come to realise that the reflecting light from the moon through the telescope lens may interfere with your ability to clearly view even our closest planets. For this reason many planet watches believe the new moon cycle is the perfect time to catch a glimpse of another world. Ganymede: Ganymede is both the largest moon of Jupiter, our Solar System's planetary behemoth, as well as the largest moon in our entire Solar system. Observations of Ganymede by the HST in 2015 suggested the existence of a subsurface saline ocean. This is because patterns in auroral belts and rocking of the magnetic field hinted at the presence of an ocean. It is estimated to be approximately 100 kilometers deep with a surface situated below a crust of 150 kilometers. Water in its life-sustaining liquid phase exists beyond our own planet, both in our Solar System--and elsewhere. With oceans of water sloshing around on 71% of our own planet's surface, Earth still remains the only planet known to have stable bodies of liquid water. Liquid water is essential for all known life forms on Earth. The existence of water on the surface of Earth is the outcome of its atmospheric pressure and a stable orbit in our Sun;s circumstellar habitable zone. The habitable zone is that Goldilocks region, surrounding a star, where the temperature is not too hot, not too cold, but just right for life sustaining water to exist in its liquid phase. However, the origin of Earth's water still remains unknown.