Accessibility links

Astronomers Debate Meaning of Word 'Planet'

The announcement last week that a 10th planet has been discovered has set off a scientific debate aimed at defining one of the most perplexing astronomical terms, the word "planet."

Scientists say most planets are either solid, like the Earth or Mars, or gas giants, such as Jupiter and Saturn. Some say the new planet, currently named UB313, as well as Pluto, does not qualify as a planet because it is simply a large rock or icy object orbiting the sun.

However, the U.S. astronomer that discovered UB313, Mike Brown, says the word "planet" is not a scientific term, but rather a cultural one.

Under international law, the International Astronomical Union in Brussels has the final say on whether Mr. Brown's discovery is classified as a planet. If they decide it is not, scientists say a side effect might be that Pluto gets stripped of its planetary status.

Some information for this report provided by AFP.