This is a terrific outburst. And since it doesn’t have a tail right now, some observers have confused it with a nova . We’ve had at least two reports of a new star.
As quoted in
When the Deep Impact probe hit Comet 9P/Tempel, there was almost no change in brightness. ... This outburst by Comet Holmes is extreme!Brian G. Marsden
We have to beef up our searches, which are now pretty dismal, so we can find out about these things before we get hit. ... It takes a dramatic event to get people's attention, and we thought the comet crash with Jupiter might have done the job. ... we tend to ignore an extraterrestrial hazard that could reduce the planet to rubble. ... What we really need is a good scare.Brian G. Marsden