London, September 23 : Astronomers have suggested that billions of years ago, a planet may have kicked planet XO-3b into a cock-eyed orbit, which would mean planets can bounce each other around like cosmic billiard balls.
According to a report in New Scientist, Guillame Hrard of the Institute of Astrophysics in Paris and colleagues detected an unusual colour shift as XO-3b passed in front of its star.
The pattern suggests that its 3.2-day orbit is tilted by 70 degrees.
"If confirmed, this might be the first planet of this type," said Hebrard, as every other known planet follows an orbit that lines up with the equator of its star.
Astronomers think they coalesced from rotating discs of material and were gradually dragged inwards to their orbits by friction with leftover gases.
"The team's discovery suggests a completely different kind of mechanism," said Fred Rasio of Northwestern University in Chicago.
Like asteroids in our solar system, planets whose paths cross could knock each other out of the orbital plane, he explained.
The second planet in this cosmic hit-and-run must have been huge, because XO-3b has the mass of 12 Jupiters.
"Normally, the little guy is one who gets kicked around," said Alan Boss of the Carnegie Institution of Washington.
Yet, such an event should cause a gravitational wobble in the star, which has not yet been detected.