COMETS IN HISTORY
Comets have been observed for thousands of years. Records show that ancient Chinese skywatchers documented the first detailed observations of comets around 613 BCE, although some believe they recorded the appearance of Halley’s Comet even earlier, in 1059 BCE. In 372 CE, on the other side of the world, Greek philosopher Aristotle was entranced by his view of a magnificent comet. This great comet had a bright-red tail that crossed a third of the sky. It was so bright that it reportedly cast shadows on the ground like the Moon.
There have been many spectacular comets throughout history. In 1577, Danish astronomer Tycho Brahe observed a great comet blazing in the sky above Europe, and the detailed measurements he made of its track across the sky led to him to propose that comets were much further away than the Moon, and weren’t just strange atmospheric phenomena. 1843 was the year of the Great March Comet, one of a class of comets now referred to as ‘sungrazers’ because they pass very close to the Sun as they whip around it, sometimes even skimming through its outer atmosphere. It developed an extremely long tail that was more than twice as long as the distance between Earth and the Sun.
In 1858, a truly great comet appeared, displaying a very long, very curved dust tail and a long, straight gas tail. Named after the Italian astronomer who first observed it, Donati’s Comet is widely acknowledged as one of the most beautiful comets ever seen. It was such a lovely sight in the sky that it inspired many artists, writers and poets. By 1910 astronomers and the public alike were looking forward to the return of Halley’s Comet, which was predicted to be easily visible to the naked eye in the spring, but Halley’s glory was rather stolen by the appearance of the Great January Comet of 1910, which many mistook for Halley’s Comet. It was much brighter and more impressive: at its brightest, with a magnitude of -5.0, the comet easily outshone Venus and had a tail that stretched 50 degrees across the sky.
Half a century later, Comet Ikeya-Seki graced our skies. When it was discovered in September 1965, it was predicted that it would become very bright as it rounded the Sun, and this proved to be the case. At its brightest it reached a magnitude of -10.0, and was visible as a star-like point with a short tail next to the Sun in the daytime
sky. The comet broke into pieces as it approached the Sun and was ripped apart by its gravity, but when it moved up into the morning sky it was still very impressive, with a long, slightly curved or hooked tail.
In 1973, astronomer Lubos Kohoutek discovered a comet which was destined to go down in history – but for the wrong reasons. When the orbit of Comet Kohoutek was calculated, it suggested that it had the potential to become extremely bright, perhaps the brightest comet for a century, and astronomers and the public alike got very excited. The press jumped on the story, hyping up the comet’s prospects incredibly, and comet fever gripped the world. Special Kohoutek-watching plane flights and sea cruises were organised, and everyone waited for the spectacle to appear… but the predictions were wrong. Although Kohoutek’s brightness reached a very respectable maximum of -3.0 as it rounded the Sun, it was nowhere near as bright as the public had expected, and was barely at 0.0 when it was most clearly visible in the sky. Kohoutek was seen – very unfairly, it has to be said – as a huge disappointment, and led to a great public disillusionment with comets and the predictions of astronomers. This is why, in the chilly spring of 1976, a much brighter and much more beautiful comet went largely unseen by the general public. Comet West grew a stunning, fanshaped tail and reached magnitude -3.0 in late February, bright enough to be observed in the daytime sky.
Two decades passed until the next great comet was painted on the sky. In 1996, as the world waited impatiently for the arrival of Comet Hale-Bopp, which was predicted to be a beautiful sight the following year, another comet, Comet Hyakutake, appeared without warning and put on a spectacular show, unfurling a banner-like tail that stretched out behind its brightgreen head for 80 degrees of sky, giving it the appearance of a lighthouse beam shining across the sky. And when it finally appeared, Hale-Bopp didn’t disappoint. The comet was first spotted in July 1995, when it was still a very long way away from the Sun, suggesting it was both unusually active and large physically. When the numbers were crunched, it was found that Hale-Bopp had the potential to become a lovely sight, but no one was prepared for just how lovely it would be. In the spring of 1997, Hale-Bopp reached magnitude -1.8 and was so big and bright in the sky – with two beautiful tails, one gold, one blue – that even nonastronomers could find it without any help.
Most great comets fade from view after a few weeks, or even days, but Hale-Bopp was visible to the naked eye for 18 months, and was seen by many millions of people around the world. Even today, all these years later, amateur astronomers who saw Comet Hale-Bopp smile and get quite misty-eyed as they remember seeing it.