The ball usually remains the same size and shape but has been reported to break up into smaller balls. Size and shape fluctuates during normal flight rarely. Usually totally silent, but sometimes emmits a buzzing, hissing, or crackling sound. In all cases, the ball either floated out of sight, exploded with a loud gunshot sounding bang, or silently disintegrated. Sometimes a slight mist or residue is reported by witnesses, and sometimes an odor described as resmbling ozone, sulfur, or nitrogen dioxide.
Visible radiation gives valuable information about physical properties.
Some of the balls were blindingly bright, others had almost no illumination and appeared grayish. Average brightness is about that of a typical 100W light bulb. Usually size, color, and brightness remain constant throughout its life, until it fades right before termination. Wide variety of colors, usually red to yellow, but sometimes white, green, bluish, or purple. Some balls have colored auras around them.