Re: Any good memorable comets coming soon? Like Ikeya-Zhang Hale-Bopp

In article <1161547963.298583.243120@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
CNJ999 <jbortle@xxxxxxx> wrote:

In point of fact, there hasn't been a "classic" Great Comet is 30
years. While H-B and Hyakutake were in a sense rather spectacular, the
brightness of either's tail (usually the most outstanding feature of a
Great Comet)

..... I thought it was the length of the tail which mattered a lot for
a comet to be considered "great" ....

were but pale representations of what nearly all of the Great Comets
of the past have displayed.

.....and there was always much more snow at Christmas in the past, and
the summers of the past were always much sunnier - right? :-)

I think we have two factors to consider here....

1. Selective memory: as time passes, we tend to remember only the best
of things we experienced, and to even make them a little better in
our memories than they actually were.

2. Light pollution getting more severe: in the past, light pollution
was less severe than today. At today's levels of light pollution,
even truly great comets appear pretty pale, unless you take the
trouble to travel to pristine skies - and few people do that.

If we ever do get another truly Great Comet, I expect today's
observers will be utterly shocked by its overall brilliance.

The best time to have been an amateur astronomer interested in comets
was between 1957 and 1976, when Great Comets were literally
commonplace, with at least half a dozen appearing in the short span of
just 20 years! In fact, it was the most prolific period for such
objects in recorded history.

.....could you please list those 6+ Great Comets which appeared during
these years? Of course they must, by your own definition above, be
bright enough and appear large enough to make both Hyakutake and
Hale-Bopp appear pale by comparison - this would require a 90+ degree
tail, and a magnitude approaching -5 WHEN THE COMET COULD BE SEEN IN
DARK SKIES well away from twilight. Any comet smaller or fainter than
that isn't likely to leave today's observers "utterly shocked", as you
phrased it above...

The only similar grouping of truly
briilliant comets took place about a century earlier than that and
there are no other contenders for the title. So...as pointed out up
stream...the typical historical odds for seeing a classical Great Comet
are no better than perhaps 2 or 3 over the course of a lifetime. Thus,
if you're wating for one...don't hold your breath!

JBortle

I've seen a few of them: Bennett in 1970, Kohoutek in 1973-74 (don't
know if you count that one), and West in 1976. And of course also
Hyakutake in 1996 and Hale-Bopp in 1997. To me, the most impressive
of them all was Hyakutake, because if its tail length and also because
it appeared close to the zenith in a fully dark night sky. Yes, comet
West was definitely brighter, but when that bright, it could be
seen only fairly low in a sky which was starting to brighten from
morning twilight, and its tail didn't appear even nearly as long
as Hyakutake's....

Most great comets are great only briefly, and fade away quite quickly.
Here Hale-Bopp was an exception: it remained near magnitude zero (its
peak brightness) for two months! No other comet in recorded history
has remained that bright for so long. Several of my friends who
aren't star gazers and who missed Hyakutake completely, enjoyed
viewing Hale-Bopp, right from the middle of the city and its light
polluted skies.

Don't belittle Hyakutake and Hale-Bopp! Even though none of them
were the brightest comets of the century, they had other qualities,
and IMO they both qualify for being considered "Great Comets", just
as much as Bennett and West were!

--
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Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
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