UPDATE: New Torino ScaleA while back I posted a copy of the Torino Scale which rates the risk of an impact by an asteroid. Astronomers recently revised the scale because they thought that it was too alarming to the general public.
The green level changed from, "Events Meriting Careful Monitoring" to "Normal"
The next-higher yellow range changed from "Events Meriting Concern" to "Meriting Attention By Astronomers"
Even the higher threat levels were softened. Level 7 of 10 was "A close encounter with an extremely significant threat of collision capable of causing global catastrophe"
to become the longwinded, "A very close encounter by a large object, which if occurring in this century, poses an unprecedented but still uncertain threat of global catastrophe. For such a threat in this century, international contingency planning is warranted, especially to determine urgently and conclusively whether or not a collision will occur."
An interesting side note on that orange level 7 - it poses and "unprecedented threat". I guess after we get to that level once, the scale has to be re-written again.
[Of course most people would believe that if there is a real threat then the general public will never be told the truth anyway.]
Revised Torino Scale