Astronomers may have found the first moon outside our solar system, a gas behemoth the size of Neptune.

Axar.az reports citing Daily Sabah.

Plenty of planets exist beyond our solar system, but a moon around one of those worlds has yet to be confirmed. Two Columbia University researchers presented their tantalizing evidence for a moon Wednesday.

The potential moon would be considerably larger than Earth — about the size of Neptune or Uranus. The planet it orbits is as big as mammoth Jupiter. This apparent super-size pairing of a gaseous moon and planet is 8,000 light-years away.

"The first exomoon is obviously an extraordinary claim and it requires extraordinary evidence," Teachey said. "Furthermore, the size we've calculated for this moon, about the size of Neptune, has hardly been anticipated and so that, too, is reason to be careful here."

He added: "We're not cracking open Champagne bottles just yet on this one."

If indeed a moon, it would be about 2 million miles (3 million kilometers) from its planet and appear twice as big in its sky, as the moon does in ours. The astronomers are uncertain how this potential moon might have formed, given its size.

"If confirmed, this finding could completely shake up our understanding of how moons are formed and what they can be made of," NASA's science mission chief Thomas Zurbuchen said in a statement.

According to the researchers, another compelling piece of evidence in favor of a moon is that the planet passed in front of its star more than an hour earlier than predicted. A moon could cause that kind of an uncertain, wobbly path, they noted.

"We've tried our best to rule out other possibilities," Kipping told reporters. "But we were unable to find any other single hypothesis which can explain all of the data we have."

Given that both the planet and its potential moon are gas giants, no one is suggesting conditions that might support life.

"But going forward, I think we're opening the doors to finding worlds like that," Teachey said