Artist's impression of exoplanet Wasp 8b. ESO/L. Calçada

 

A new study of exoplanets finds that many have orbits that are tilted relative to the equators of the stars they orbit. Some even revolve in the opposite direction (retrograde) to the rotation of the star.

Standard theory requires planets to move in the same direction as the star and to orbit in or near to the star’s equatorial plane. This is because the planets are thought to condense out of a rotating protoplanetary disc that is spun out as the star collapses from a cloud of gas.

In an electrical system, planets may form in the polar “jets” (Birkeland currents) of young stars (such as Herbig-Haro objects), or they may be ejected from active stars much like CMEs from the Sun. When the polar jet discharge quenches, the planets will “scatter like buckshot,” as seen in lab discharges. The planets may then be gravitationally captured in any configuration of orbit, although a prograde equatorial configuration is most likely.

Mel Acheson