Io (Jupiter) is the densest moon in the Solar System.
Density is one of the simplest non-fundamental properties of matter you can imagine. Every object that exists, from the microscopic to the astronomical, has a certain amount of energy-at-rest intrinsic to it: what we commonly call mass. These objects also take up a given amount of space in three dimensions: what we know as volume. Density is just the ratio of these two properties: the mass of an object divided by its volume.
Our Solar System itself was formed some 4.5 billion years ago the way all solar systems are formed: from a cloud of gas in a star-forming region that contracted and collapsed under its own gravity. Recently, thanks to observatories such as ALMA (the Atacama Large Millimetre/submillimetre Array), we’ve been able to directly image and analyze the protoplanetary disks that form around these newborn stars for the first time.
Picture Credit : Google
