Could there be more planets in our solar system? Some scientists say yes.

In a study published in the journal Monthly Notices of the Royal Astronomical Society, British and Spanish astronomers say there may be at least two more planets hiding behind Pluto.

There are currently eight known planets in our solar system, after Pluto was "demoted" to the status of "dwarf planet" by the International Astronomical Union in 2006.

Former NASA astronaut Mike Massimino said on "America's Newsroom" that it will be a major discovery if there actually are more planets in our solar system.

"Would it affect our daily life? Maybe not so much. But certainly we'd have to rewrite a few of the astronomy books," Massimino said.

He explained that astronomers found that there were many rocks outside Pluto that were being disturbed by gravity.

"So they see something else pulling on them and disturbing the orbit and they don't know what that is," Massimino said. "So the theory that they have is that there's more planets - really big ones - way far away, out in the solar system."

He said he doesn't believe that the scientists have seen the planets and the only actual evidence for their existence is the gravitational attraction.

"There's more stuff out there than we can account for," he said, noting that even with concepts like dark matter and dark energy we can only recognize about 10-percent of the energy in the universe.

"We really don't know what the heck is going on out there. Very exciting stuff."

Watch the clip above.