In the distant reaches of the solar system are many icy objects that resemble snowmen — pairs of conjoined spheres. Now, a new study reveals the simple way in which these mysterious objects might form.
Beyond the orbit of Neptune lie icy building blocks from the dawn of the solar system known as planetesimals. Much like snowballs are composed of clusters of snowflakes, planetesimals likely arose within the disks of dust that encircled the newborn sun from clouds of pebble-sized objects pulled together by their mutual gravitational attraction.
