I can't decide on my favorite comet, so here are my five, in order of dates observed:
-- 1P/Halley - This was my first comet. Discovered in antiquity, this comet's periodicity was theorized by Edmond Halley and verified by its return in 1835, thus confirming that comets are actually objects orbiting the sun. Its dramatic return in 1910 was a sensation. Unfortunately, its 1986 return was the comet's poorest apparition in its entire 2000+ years of observation. Even though, it was still a nice comet in its own right.
-- C/1996 B2 (Hyakutake) - If I had to pick a favorite comet, this may be it. Hyakutake was briefly a spectacle to behold. Discovered in late January, it would soon make its closest approach to Earth in March. It was fascinating to watch as it brighten to naked-eye visibility, and then rapidly increase in brightness and size each night. By late March, it passed 0.1 AU from the earth. Its appearance was truly great, the most dramatic I've seen. The 0-magnitude coma, about the size of a full moon, was near Polaris. The gossamer tail stretched about 60 degrees (40 deg. was obvious) through the Big Dipper, overhead, and then to a point near Coma Berenices in the south. It was effectively a giant sundial in the sky. As the comet headed to perihelion, it shrunk in size and brightness, but became more impressive visually. It was a wonderful sight in Perseus just before it disappeared into twilight. All of this occurred after comet Hale-Bopp was discovered in 1995 and before its perihelion in 1997.
-- C/1995 O1 (Hale-Bopp) - This was the Big One seen by millions. It was the largest comet since the great one in 1811 (and perhaps it even surpassed that one). Unfortunately, it didn’t pass particularly close to the earth. (If it had passed perihelion in December instead of April, it would have been a monster!). This comet had steady and convenient visibility for a few months as it slowly tracked through the northern sky. By late March and early April, it was visible in the evening for all in the northern hemisphere. It was easily visible in urban areas and was a glorious sight under dark skies. It was even visible during the total eclipse of 1997. The comet’s clear bifurcation of gas and dust tails was distinctive among comets in recent memory. The brilliant inner coma, with its spiraling jet, was fascinating to observe in telescopes.
-- C/2006 P1 (McNaught) - This would have been my favorite by far if I had been in the southern hemisphere at the time. What a sight it would have been! Still, I had a decent view of it just before perihelion. At magnitude -3, it was the brightest comet I’ve seen. Even though it was deep in twilight, it was plainly visible. Many people probably mistook it for a contrail. Unfortunately, the weather and my work schedule didn’t quite cooperate for me to attempt spotting it at perihelion. Once past the sun and into southern twilight… wow! That tail was so sweeping and extensive, portions of it could still be seen from the northern hemisphere by some.
-- 17P/Holmes - This comet was a unique and delightful surprise, even if not unprecedented. I had written this one off, as it wasn’t due to exceed magnitude 14. But then the alert went out in October of 2007. Comet Holmes was magnitude 2 and nearly stellar. When I stepped outside, I could see a new ‘star’ in Perseus that wasn’t there before. Through the telescope, it was very compact. Over the coming days and weeks, the coma slowly expanded into a ring with a sort of double inner coma. A complex gas tail also developed. As this was due to a tremendous single outburst, the comet retained its 2nd magnitude brightness as it slowly reached to greater than a full-moon’s width. Continuing into 2008, it was still visible as it continued to fade. As a previous outburst occurred in 1892, this comet should be closely monitored during each subsequent apparition.
Honorable mention:
- C/2020 F3 (NEOWISE) - This may be the most beautiful of comets I’ve been able to observe. While stunning in photos, it was a bit underwhelming visually in comparison. It was modestly visible to the naked eye, and impressive with binoculars.
