The object some astronomers believe to be the 10th planet in our Solar System may have a moon.
The experts say that because the planet Sedna rotates more slowly on itself, it may have a satellite orbiting it.
"Sedna revolves once every 40 days, suggesting it might have a moon slowing its twirl" said Dr Mike Brown of the of the California Institute of Technology.
"We're hoping to get some observations from the Hubble Telescope that should put that question to rest" he added.
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