Black dot in sky breaks into 4 pieces--then collapses back into a single dot. Then disappears.We were at Best Buy (electronics store). We just arrived in the car (parked south of the store and looking southwest)when we saw a black dot in the sky floating about 45 degrees above the horizon. The dot temporarily split into four parts for about twenty seconds and then collapsed back into a single circle. It started floating again and appeared to get smaller and smaller as though moving away (or shrinking upon itself). Finally, as we were watching, it disappeared into the sky. Although it was late afternoon and the sun was setting, the sky was still bright. The object definitely visible. There were no jet trails or other characteristics.