Pebbles Form Planets

Summary

The secret to the formation of planets may lie in ordinary static electricity—the same phenomenon that can make your hair stand on end or give you an electric shock after walking across a carpet. A new study, published in Nature Astronomy, suggests that static electricity allows tiny dust particles in protoplanetary disks—the rotating platters of gas and dust that form around young stars—to clump together into “pebbles” that are large enough to play a role in the formation of planets.The image above shows basaltic beads, each measuring 0.55 millimeters, that were used in an experiment, which took place aboard a suborbital rocket.The findings help resolve a mystery that has shrouded something called the bouncing barrier—the size threshold that particles must reach in order to rely on gravity to join with other particles—says lead author of the study Jens Teiser, an astrophysicist at the University of Duisburg-Essen in Germany. ADVERTISEMENT Nautilus Members enjoy an ad-free experience. Log in or Join now . The dust particles need static electricity to make them “sticky” enough to cluster into pebbles that can form planets.Only when particles grow larger than this threshold size—roughly a quarter of an inch, depending on conditions—can they eventually join to form rocky “planetesimals,” from about half a mile to 100 miles across, that scientists think then collide within protoplanetary disks to create planets like Earth.Smaller “dust particles don’t stick together,” Teiser says, unless they have an electrostatic charge.Static electricity is produced when different objects with an imbalance of positive and negative charges make contact, which results in an electrostatic charge. In this case, the electrostatic charge is generated by collisions between tiny dust particles, which can cause them to either gain electrons or lose electrons, resulting in a negative or a positive charge, respectively. Oppositely charged particles will then attract each other—according to the l...