Everyone eagerly anticipated Halley’s comet showing up in April 1910. It came as quite a surprise, then, when another brighter comet appeared just four months before: the Daylight Comet.
By 1910, the periodic nature of Halley’s Comet was common knowledge. Its appearance in the night sky in April would not be a surprise; after all, it had turned up right on schedule in 1835 and 1758, following Edmond Halley’s predictions (and later computations) very closely. Its arrival was hotly anticipated. Mark Twain, born under Halley’s Comet in 1835, anticipated his own death with its return. Charlatans sold anti-comet pills following an astronomer’s prediction that Halley’s tail would poison the globe.
When Halley’s Comet did arrive, right on time, Mark Twain died. The planet did pass through Halley’s tail, and we weren’t all poisoned. But for many people, Halley’s Comet was an anticlimax. They had seen a larger and more surprising comet just four months earlier. The Great January Comet pipped Halley’s at the post.
Comets can be roughly divided up into short-period and long-period categories. Short-period comets reappear in our skies at regular intervals, like Halley’s. Long-period comets shoot much further out away from the sun, and so may not reappear for thousands of years… or they may not return at all. The Great January Comet was just such a comet.
It was bright, perhaps the brightest comet in the 20th century. (Another comet in 1965 is the only challenger for that title.) And it was big, with a tail stretching 50 degrees across the sky. (In comparison, the Moon only takes up half a degree.) At its peak, it was even visible during the day, hence its other name: the Daylight Comet. By the time Halley’s Comet showed up four months later, everyone had seen something more spectacular.
(End note: I saw Halley’s Comet as a child, and I hope to see it again before I die. If I’m still writing for this website in 2061, you’ll know I made it.)