Sky & Telescope - July 2020 - 33

10.5-magnitude blur roughly 15′ eastward. By the onset of
twilight, Hale had detected the telltale motion of what was
surely a comet. The burning question was: Had he snagged it
before anyone else?
The answer was yes, but just barely. At virtually the
same moment as Hale, Thomas Bopp was also eyeing M70
at an informal star party in the Arizona desert, some 90
miles south of Phoenix. Bopp was using a friend's 17.5-inch
Dobsonian reﬂector telescope when he noticed a faint, fuzzy
interloper slowly chasing M70 through the ﬁeld of view. Bopp
had never observed a comet before, but after checking his star
charts and then detecting motion in the object, he realized he
was onto something.
Meanwhile, Alan Hale had emailed the world clearinghouse for comet discoveries, the Central Bureau for Astronomical Telegrams (CBAT). Tom Bopp returned home as
quickly as possible and also dispatched a telegram to CBAT.
The next morning, CBAT supplied the amazing news both
men wanted to hear - they'd won the cometary lottery. On
July 23rd, IAU Circular 6187 alerted the world to a new comet
designated C/1995 O1. But that was all. No fanfare - C/1995
O1 was just like many similarly faint comets discovered each
year. The hyphenated moniker "Hale-Bopp" was added a few
days later. And that was that.
Then the data starting coming in. The newfound object
was 7.2 astronomical units (a.u.) from the Sun, well beyond
the orbit of Jupiter, making it unusually bright for such a
great distance. Indeed, it was the most remote comet ever
found with amateur telescopes. Perhaps not surprisingly,
then, measurements indicated the ghostly glow could develop
into a Great Comet. Alan Hale and Tom Bopp had won a
bigger prize than they'd initially realized. Precisely how big,
though, no one knew for certain.

Duds from Space
I was somewhat skeptical about the "Great" part of the
description. Hale-Bopp wouldn't reach perihelion until April
1, 1997, leaving lots of time for it to ﬁ zzle into insigniﬁcance,
as many comets do. Borrowing a line from Shakespeare's
Hamlet about an unlikely ghost, my pessimistic mantra was:
"Tush, tush, 'twill not appear."
My outlook had been tainted by the Curse of Kohoutek, a
dull play that folded on opening night. Comet Kohoutek was
discovered by Czech astronomer Luboš Kohoutek on March 7,
1973, and - subsequently heralded the "Comet of the Century" - was expected to dominate the northern sky at the
end of the year. As a young show presenter at the H. R. MacMillan Planetarium in Vancouver, British Columbia, I was
thrilled when the director asked me to staff a "comet desk"
to ﬁeld inquiries from the public and media. Unfortunately,
the fab phenom failed to live up to its advance billing, and
the overhyped Comet of the Century decayed into the dud
of the decade. Although astronomers considered Kohoutek a
moderately impressive specimen (4th-magnitude, nice tail), I
couldn't see it through all the egg on my face.

p B&W BEAUTY This photo emphasizes Hale-Bopp's brilliant coma
and the intricate, braided structure of its delicate ion tail. Dennis di
Cicco recorded this view with an f/1.5 Celestron Schmidt camera on
March 27, 1997.

Frustrated to the max, I formulated Ken's Comet Law:
Early-discovery comets are potential time bombs of disappointment. After Kohoutek, my "law" was bolstered by other
icy visitors, Halley's Comet chief among them. No amount
of caution from planetarium staff could prevent the most
famous comet in history from becoming a massive public
downer. In 1990, Comet Austin was another ﬁasco that
made my planetarium life miserable. And, post-2000, who
can forget the utterly forgettable Comet ISON (C/2012 S1)?
Magazines of every stripe hyped it to the hilt. "ISON blazes
into glory" screamed one headline. "All eyes are on ISON for
a show 4 billion years in the making" made me cringe. Naturally, ISON was DOA.

Some Showstoppers
Despite the frequent disappointments, the cometary brigade
wasn't completely without big, bold exceptions. Over the past
half century, Northern Hemisphere observers of a certain age
(including yours truly) have been fortunate enough to marvel
at four truly newsworthy comets. Curiously, all four reached
their peak during spring.
Comet Bennett zoomed northward in March 1970 to rise
tail-ﬁrst in the predawn sky, its nucleus outshining Deneb.
Bennett became a feathery, circumpolar exclamation mark for
several weeks. In March 1976, Comet West, another tail-ﬁrst
morning riser, was even brighter and sported a broad, curving
s k y a n d t e l e s c o p e . o r g * J U LY 2 0 2 0

http://www.skyandtelescope.org

Sky & Telescope - July 2020

Table of Contents for the Digital Edition of Sky & Telescope - July 2020