Responding to the public's fascination with-and sometimes undue alarm over-possible threats from asteroids, a scale developed by astronomers rates the likelihood that a particular asteroid or comet may collide with Earth.

• Aa scale developed by astronomers rates the likelihood that a particular asteroid or comet may  
• Ba scale that astronomers have developed rates how likely it is for a particular asteroid or comet to  
• Castronomers have developed a scale to rate how likely a particular asteroid or comet will be to  
• Dastronomers have developed a scale for rating the likelihood that a particular asteroid or comet will  
• Eastronomers have developed a scale that rates the likelihood of a particular asteroid or comet that may.