Astronomers have discovered the first known example of a "tilted" solar system – that is, a star whose equator tilts steeply away from the plane in which its planets orbit. It's an unprecedented find, one that could help explain how some planets wind up in wonky orbits.
Earth, like most planets that we know of (so far), orbits more or less in the same plane as the equator of its parent star (7.2 degrees out-of-plane, to be exact.) But in research published in the latest issue of Science, a team of researchers led by NASA astronomer Daniel Huber has identified two planets that orbit at staggering 45 degrees relative to the equator of their parent star, red giant Kepler 56. Scientists have spotted similar tilts in other systems, but until now thought such an arrangement would require the presence of a massive, gas giant planet close to the parent star to do so. Kepler 56 has no such giant. What it does have is a third, outer planet, that researchers hypothesize pulls the planets into and steadies them along their slanted orbital course.
To find out what caused the tilting, the astronomers measured the velocity of Kepler-56 through space using the 10-metre Keck I telescope on Mauna Kea in Hawaii. “That revealed the culprit,” Huber says: a distant body whose gravitational pull tugs the star and also tilts the planets’ orbits. Despite the enormous tilt, the planets' orbits stay aligned with each other because they're in resonance: one planet takes twice as long as the other to circle the star, so they periodically nudge each other through their gravity. Their orbits therefore remain co-planar even as they deviate radically from the star's equator.
“It’s a fascinating discovery,” said Amaury Triaud, an astronomer at the Massachusetts Institute of Technology in Cambridge. “It’s nature: you observe, and you find extraordinary stuff.” Of course, the irony of discoveries like this one is that, with so much of OUR GALAXY ALONE left to explore, even "extraordinary" discoveries may not be so extraordinary in the grand scheme of things. In other words: just because this is the first instance of a radically tilted solar system we've stumbled across, doesn't mean there aren't many, many more of them out there, waiting to be discovered. Which, I suppose is sort of an extraordinary realization in its own right.
Read more at Nature. Read the full study over at Science.