My own unscientific study of my girlfriend and her children confirms this. When asked to name comets they came up with “Hayley’s and that one where all the people killed themselves” (Halebop).

]]>The article says the range of brightness is anywhere between magnitudes of -6 to -16, not -11 (which I assume you averaged?)

No matter how it is calculated, I cannot get past -10 magnitude, and this is agreed in the sources you linked.

Comet magnitude are calculated by m = H + 5 logDelta + 10 log r ; where H is the absolute magnitude, Delta is the Earth’s Distance, and r is the Sun’s Distance.

Firstly, distance of 2 million kilometres (0.013AU) for the sun is highly suspect, as the error is more than the distance! Few comets pass within 0.3 AU.

All hinges on the given absolute magnitude, which for most comets is very unreliable. At the present distance of this comet, we can only assume an average value. (The German source may have used the maximum value, but it actually doesn’t say how this was done.) Only five comets have been above ?1.5 absolute magnitude, but the average is around 2 to 6; say 4.

At 0.3 AU; m= 4+ 5 log(0.1)+10 log(1) = 0.0 magnitude

At 0.013AU, this is ; m=4 + 5 log (0.013)+10(log1) = -5.4

At 2 million kilometres, If m = 4 + 5 log (0.013)+ log(1) = -10.93

The highest value for H is ?1.8, meaning the best magnitude possible is ?11.3!!

Where does the ?16 come from? It is impossible!

This source is unreliable!

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