Department of Astrophysical Sciences

In the Solar system, the planets follow orbits that are aligned with the Sun's equatorial plane to within about 7 degrees.  What about planets around other stars?  Recently we have measured the orbital orientations (relative to their parent stars' equators) of more than a dozen different exoplanets, using a technique first theorized in the 19th century.  Many systems have good alignment, as in the Solar system -- but there are a few surprises. I will discuss these results and their implications for theories of planet formation and migration.