PASADENA, Calif., March 24 (UPI) -- U.S. experts say known planets outside of Earth's solar system, currently numbered at 277, could soon include smaller planets that are closer to Earth's size.

Most of the currently known "extrasolar" planets are gas giants similar to Jupiter and Saturn -- hundreds of times larger than Earth -- that are not believed to be capable of supporting life, but recent discoveries, including a planet with organic methane in its atmosphere, have raised hopes that more life-friendly plants may be found in the near future, The Washington Post (NYSE:WPO) reported Monday.

"This is an absolutely astounding time for this field," said Mark Swain of the National Aeronautics and Space Administration's Jet Propulsion Laboratory in California, who reported the discovery of the methane-rich planet last week.

Sara Seager, a Massachusetts Institute of Technology professor and expert on extrasolar planets, said technology advances could lead to finding Earth-like planets.

"We've already been able to detect planets with only five or 10 times the mass of the Earth," she said. "If the technology improves a bit, with another push, we'll find Earths."