An artist's interpretation of NASA's planet-hunting Kepler observatory in space.
This story was updated Aug. 26 at 12 a.m. ET.
NASA is expected to make a major announcement today on the progress of its Kepler spacecraft, which has been staring at one patch of space for evidence of other worlds.
The space agency has set an afternoon teleconference with reporters to discuss the results from Kepler, which include the "discovery of an intriguing planetary system," according to a space agency statement released Monday. [The Strangest Alien Planets]
Participating in the teleconference will be senior NASA scientists and Kepler mission researchers, including principal investigator William Borucki of ?the space agency's Ames Research Center in Moffett Field, Calif.
The Kepler space observatory hunts for Earth-like planets around other stars. In June, mission scientists announced that the telescope had found over 700 candidates, including five systems that appear to have more than one transiting planet.
The spacecraft monitors stars for subtle changes in their brightness, which could indicate that alien planets are passing in front of them as seen from Earth. To date, astronomers have discovered more than 400 extrasolar planets around stars beyond our solar system.
NASA launched the $600 million Kepler spacecraft in March 2009. It is currently staring at a patch of the Milky Way that contains over 156,000 stars ? a star field in the constellations Cygnus and Lyra.
Astronomers have been using the data from Kepler to determine whether orbiting planets are responsible for the variation in brightness of several hundred stars.
Follow-up observations are necessary to distinguish between actual planets and false alarms such as binary stars, which are two stars that orbit each other.
Today's announcement comes on the heels of a separate discovery of at least five planets ? with hints of two more ? circling around a star in an arrangement similar to our own solar system.
That discovery (which included up to seven alien planets ? including one that could be 1.4 times the mass of Earth) was made by astronomers using the European Southern Observatory in Chile. They discovered the planets 127 light-years from Earth around the star HD 10180 in a pattern that looks strikingly like our solar system, only in a more compact arrangement.
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