The Hubble Space Telescope has taken the first definitive images of a dark cloud on the planet Uranus. Although there have been unconfirmed sightings of darker colored spots on Uranus, no prior images taken have been able to prove the existence of the cloud. The Advanced Camera for Surveys originally took the picture on August 23, while the research team later found the cloud again the following day. U.S. astronomers from the University of Wisconsin stated that the dark spot is 1,100 miles by 1,900 miles in dimension. The dark vortex is large enough that it could engulf two-thirds of the United States.

Scientists are not sure why the dark spot can be seen now and wasn't previously spotted before. Some researchers believe the Uranian northern spring may be the cause of the perplexing cloud -- Located at latitude of 27 degrees in the Uranian atmosphere; the location is becoming fully exposed to sunlight for the first time in years. As the planet approaches its equinox, which will occur in December 2007, it may become more “Neptune-like.”

In other Hubble-related news, the Advanced Camera for Surveys, the most used instrument on the Hubble, shut down unexpectedly yesterday. Researchers believe the problem occurred in the High Resolution Channel, a camera that is only used for about 10 percent of the observations.