Why Is the Solar System So Bizarre?

All manner of planets circling other stars have been popping up of late: big ones, little ones; gassy ones, rocky ones; hot ones, cold ones. But the freakish diversity of worlds starts much closer to home. From the 1960s to the 1980s, space probes returned the first close-up looks at eight of the then-nine planets. To researchers expecting a simple story that would explain what shaped our solar system, the observations sent a sobering message: in your dreams. Today, enigmas such as Mercury's makeup (mostly iron core, with a thin veneer of rock) and Uranus's skewed magnetic field continue to bedevil planetary scientists, and no tidy resolution is in sight. Part of Science's special section, The Mysteries of Astronomy.

Read the Full Text