Europa is the sixth-largest moon in the Solar System and Jupiter’s fourth-largest satellite. Despite its cracked and discolored appearance, it is the smoothest solid object in the Solar System; its highest peaks, of which there are few, only reach a few hundred meters tall, and large craters are rare. The crisscrossed streaks and splotches that run across the terrain are probably mostly due to relatively shallow fractures and different compositions of the ground, not the enormous canyons present on some other worlds.
This smoothness means that the surface of the moon is fairly young, probably tens of millions of years old rather than billions, like some other objects. Somehow, the ice is being resurfaced and smoothed out faster than on many other worlds. The question of why that happens has not been definitively answered yet, but it probably has something to do with what’s below Europa’s surface.
This frigid moon of Jupiter hides a tantalizing secret: a probable sea containing twice as much water as all of Earth’s oceans combined. While the icy shell is hard as a rock, the interior is warmer, heated by the flexing of its iron core and stone mantle. The side of Europa that’s closest to Jupiter experiences a stronger pull than the farther side, stretching the entire moon and probably causing the long cracks that run across its surface as well as heating the interior.
The evidence that there is some sort of water or slush beneath Europa’s surface is fairly strong, based on models of how a buried ocean would affect the ice above it. Measurements of the moon’s magnetic field also hinted that there is some sort of electrically conductive fluid — such as salty water —flowing under the surface. There are even images from the Hubble Space Telescope that appear to show huge plumes of water vapor erupting from Europa’s south pole, although they are not high-resolution enough to be definitive. Continue reading from The Planetary Society
Europa: A guide to Jupiter's icy moon (Space.com)
Europa (moon) facts for kids (Kiddle)
Facts about Jupiter's Moon, Europa (The Planets)
Forget the Moon—We Should Go to Jupiter's Idyllic Europa (Wired)
Jupiter's Ocean Moon Europa Is Ready for Its Close-up (Scientific American)
NASA swooped over ocean world Europa and captured weird, stunning footage (Mashable)
Our solar system formed about 4.5 billion years ago from a dense cloud of interstellar gas and dust. The cloud collapsed, possibly due to the shockwave of a nearby exploding star, called a supernova. When this dust cloud collapsed, it formed a solar nebula—a spinning, swirling disk of material.
At the center, gravity pulled more and more material in. Eventually the pressure in the core was so great that hydrogen atoms began to combine and form helium, releasing a tremendous amount of energy. With that, our Sun was born, and it eventually amassed more than 99 percent of the available matter. Continue reading from NASA
