Hyakutake: The Great "Earthgrazing" Comet of 1996

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I don't care about the naming of the comet. If many people could enjoy that comet, that is the happiest thing for me.

-- Yuji Hyakutake, 1996

Comet Hyakutake as photographed by Michael O’Gara on the morning of
March 27, 1996, with his Minolta with 50 mm lens, guided on the comet’s
head for approximately 1 minute, using Kodak 800 film. Copyright Michael
O’Gara, used by permission. [The photo was taken at almost the same time
that the drawing below was made, approximately 07:50 UT March 27.]

Comet Hyakutake as drawn by Bruce Kamiat on the morning of March 27, 1996,
over a copy of Tirion’s “Sky Atlas 2000”. From the artist’s notes: The view is
slightly distorted due to the flat projection of the chart. Artistic license was used
to preserve the appearance of the tail; its tip is thus displaced east by several minutes
of RA; it actually appeared to fade out in the middle of the Big Dipper’s bowl.
This would have required giving the tail a curved appearance. The tail appeared
quite straight, as shown here. Copyright Bruce Kamiat; used by permission.

In early 1996, as the world anxiously awaited the arrival of Comet Hale-Bopp —discovered the previous summer at a record distance from the Sun and still over a year away from perihelion—another comet appeared that soon become one of the most spectacular of the Twentieth Century. On January 30, 1996, Yuji Hyakutake of Hayato, Japan discovered his second comet, an 11th magnitude glow in Libra, in giant (150mm) Fujinon binoculars. He had found his first comet, C/1995 Y1 (Hyakutake) in nearly the same position in the sky just five weeks earlier, on Christmas Day, 1995.

Orbital calculations showed that within two months, the new comet—designated C/1996 B2 (Hyakutake)—would pass a mere 0.102 AU, or 15 million km, from Earth, and would be superbly placed for Northern Hemisphere viewers when at its closest, passing through Bootes and Ursa Major and very near Polaris, just half a degree from the North Celestial Pole and visible all night. It would reach perihelion on May 1, 1996, at 0.23 AU from the Sun. All this combined to make astronomers optimistic that the comet would perform well—the main worry was that the comet might be intrinsically faint and be a washout despite the positive factors. This proved not to be the case, and Hyakutake put on a show that will be remembered for a long time, hanging in the sky all night with a large, blue-green head and a long, straight gas tail that appeared to swing like a searchlight as the heavens rotated over the course of the night. Many observers who saw both Hyakutake and Hale-Bopp from dark-sky locations have asserted that Hyakutake was decidedly more impressive.

I first saw Comet Hyakutake at around 2 a.m. on March 11, 1996, in my 7x50 binoculars. It was then below Alpha Librae, a quite obvious fuzzball even from my light-stricken Brooklyn, NY neighborhood and despite a nearby third-quarter Moon. By March 16, I could just make it out with the naked eye. My description: “Bright central coma, more ghostly outer coma, no sign yet of tail.”

I spent Friday night, March 22, with friends on City Island in the Bronx; we went out in the early evening and could briefly make out the bright head of the comet amid the clouds. We were thinking of driving north into Westchester County or Connecticut if it cleared, but it stayed cloudy past midnight. I woke up around 3 a.m. and stepped outside to find the sky had cleared and the bright, fuzzy head of the comet hung nearly overhead. I quickly got dressed and walked out to a nearby boatyard, where I watched the comet, second magnitude or brighter and with a degree or two of tail visible, as it passed by Epsilon Boötis, north of Arcturus.

I spent the next two nights in Westport, Connecticut. Each night there were clouds in the early evening, and then a clearing before midnight. I remember thinking, when I walked out into the driveway after it had cleared on Saturday and got a good look at the comet, that this was the comet I had waited 20 years to see. (I had seen Comet West in 1976, and wondered if I would ever again see its like.) It hung nearly overhead, sporting a greenish-tinted head and narrow, straight tail. I took a long walk through my hometown with that awesome comet high in the sky. The next night was similar; I showed Hyakutake to my mother (who thanks to me has seen more comets than many astronomer types), and then walked beneath the comet, whose central condensation was as bright as Spica and which overall was nearly zero magnitude. Saturday night I saw about 7 degrees of tail; Sunday it stretched about a dozen degrees, and there was one tantalizing moment when I could see about twice that.

The night of March 26-27 I was back in Brooklyn, and viewed the comet from Prospect Park. It appeared as a fuzzy patch very close to Polaris, and of comparable brightness. (Observers at dark-sky sites had a far more spectacular view as it hung near the pole with its tail near maximum length. The photo and the drawing that accompany this article were made that night.)

I got my last view of Hyakutake in early April from Washington Square Park in Manhattan; it was then very difficult to the unaided eye amid the glare of streetlights. All told, I saw the comet on about 15 nights, a dozen naked-eye sightings including 10 from light-stricken NYC.

Astronomers were hoping that the comet would brighten again as it approached perihelion, but this was not to happen.

Sadly, Yuji Hyakutake passed away on April 10, 2002, at age 51 of an aortic aneurysm.

E-mail to tonyhoffman [at] earthlink [dot] net