by Gemma Reguera — Mod­ern Earth is noth­ing like it was in its early days. Our planet was formed some 4.56 bil­lion years ago when a gi­ant stel­lar cloud col­lapsed on it­self due its mas­sive size and grav­i­ta­tional force. The ex­plo­sion also gen­er­ated the sun and many other plan­e­tary bod­ies, in­clud­ing those that would...