The Kepler Telescope, launched in March, discovered the two new heavenly bodies, each circling its own star.
Telescope chief scientist Bill Borucki of NASA said the objects are thousands of degrees hotter than the stars they circle. That means they probably aren't planets. They are bigger and hotter than planets in our solar system, including dwarf planets.
"The universe keeps making strange things stranger than we can think of in our imagination," said Jon Morse, head of astrophysics for NASA.
The new discoveries don't quite fit into any definition of known astronomical objects and so far don't have a classification of their own.
'Hot companions'
Details about the mystery objects were presented on Monday at a meeting of the American Astronomical Society in Washington.
For now, NASA researcher Jason Rowe, who found the objects, said he calls them "hot companions".
How hot? Try 26,000 degrees Fahrenheit (14,425 Celsius). That is hot enough to melt lead or iron.
There are two leading theories for what the objects might be and those theories cover both ends of the cosmic life cycle:
* Rowe suggests they are newly born planets. New planets have extremely high temperatures and in this case Rowe speculates they might be only about 200 million years old.
* Ronald Gilliland of the Space Telescope Science Institute says they could be white dwarf stars that are dying and stripping off their outer shells and shrinking.
