WASHINGTON - US space agency NASA announced Wednesday that astronomers using the Spitzer Space Telescope have detected what they believe is a planet two-thirds the size of Earth.

An alien world just two-thirds the size of Earth - one of the smallest on record - detected by NASA's Spitzer Space Telescope is seen in this NASA artist's illustration released by NASA on July 18, 2012. [Photo/Agencies]

The exoplanet candidate, called UCF-1.01, is located a mere 33 light-years away, making it possibly the nearest world to our solar system that is smaller than our home planet.

Exoplanets circle stars beyond the sun. Only a handful smaller than Earth have been found so far. Scientists aided by Spitzer have performed transit studies on known exoplanets, but UCF-1.01 is the first ever identified with the telescope, pointing to a possible role for Spitzer in helping discover potentially habitable, terrestrial-sized worlds.

"We have found strong evidence for a very small, very hot and very near planet with the help of the Spitzer Space Telescope," said Kevin Stevenson with the University of Central Florida in Orlando. "Identifying nearby small planets such as UCF-1.01 may one day lead to their characterization using future instruments."