Scientists said they have found evidence of a giant planet far out in our solar system.In a statement, the California Institute of Technology—Caltech—said this planet travels a very strange “longandthin orbit in the distant solar system.”The discovery was made by two researchers at Caltech: Konstantin Batygin and Mike Brown. They used mathematical modeling and computer simulations(模拟) to find the planet.So far, there have not been any direct observations of the planet.
“My jaw hit the floor,” said astronomer(宇航员) Mike Brown, the moment he realized there might be a ninth planet.
The scientists said it would take this planet 10,000 to 20,000 years just to make one full orbit around the sun. The new planet, called “Planet Nine”, has a mass about 10 times the size of Earth.If they are right, the newly found planet would be the ninth planet in our solar system. Pluto(冥王星) had been called the ninth planet until 2006, when it was renamed a “dwarf planet.”
Actual confirmation of a ninth planet would be very big news. “This would be a real ninth planet,” Brown said in the statement. “There have only been two true planets discovered since ancient times, and this would be a third. It's a pretty substantial chunk of our solar system that's still out there to be found, which is pretty exciting.”
While they did not get a picture of “Planet Nine” yet, the scientists say they are using the biggest—and best—telescopes on Earth to try to find “Planet Nine.”They are also working on improving their computer simulations. They want to find out more about “Planet Nine’s” orbit, and its impact on the outer part of our solar system.

To find“Planet Nine”, scientists are using allthe followingEXCEPT ________.