Discovery of mismatched orbits hints at a violent past
Like bugs glued to a phonograph record, the solar system’s planets all orbit the sun in nearly the same plane. A new finding shatters the notion that planetary systems around other stars all have a similarly flattened arrangement. Newly reported measurements reveal that the two outermost planets known to circle a nearby sunlike star called Upsilon Andromedae are wildly misaligned, orbiting the star in different planes separated by 30 degrees.
The observations include ground-based measurements of the back-and-forth motion, or wobble, of Upsilon Andromedae due to the tug of its orbiting planets. But most critical were Hubble Space Telescope observations that tracked the two-dimensional motion of the star as it pirouetted across the sky, orbiting the center of mass of its planetary system.
The new measurements are the first to accurately determine the angle between the orbits of two extrasolar planets circling a sunlike star, says Barbara McArthur of the Universi