Star Points for January 2010 by Curtis Roelle The Great January Comet One hundred years ago this month, the world was anticipating the predicted return of Comet Halley. But to everyone's surprise, a new, unpredicted, and unexpectedly bright comet appeared in the cold daytime sky, and eventually continued on into the frigid January night before fading away. Although Comet Halley had been observed and recorded for more than 20 centuries, apparently no one recognized that it was actually the same comet making regular appearances every 76 years as it orbited the sun. The first to do so was Sir Edmund Halley, a contemporary of Sir Isaac Newton, who successfully predicted that the comet would return in 1758. It returned again in 1835. So, as the year 1910 dawned, the confidence in, and anticipation of, yet another fantastic return was high. This was the backdrop for the arrival of the "Great January Comet" (a.k.a. "Great Daylight Comet") of 1910. Three miners at a South African diamond mine were the first to glimpse the comet at sunrise, and they spent 20 minutes watching it. According to Gary W. Kronk's "Comets: A Descriptive Catalog," a report was sent out incorrectly stating that Comet Halley had been visually recovered at last. Halley had previously been recovered photographically on September 11, 1909. By the Spring of 1910 it would became a naked eye comet sporting a 90 degree long tail. It didn't take astronomers long to realize that the new comet could not possibly be Halley. As the month of January progressed, the unidentified comet stayed near the sun during daylight and, according to Kronk, looked like "a snowy-white object with a tail 1 degree long." By month's end the comet moved into the night sky. Even with interference from moonlight, the comet remained very bright, with a tail 18 degrees long. Then, as the moon faded, darkening the sky over the next few days, the tail seemed to grow to two or three times that length. Over the next few months the comet faded, and was last seen in July. It is expected to return – in another four million years. The January comet was one of the brightest of the 20th century. According to a list of the twenty brightest comets of the 20th century compiled by comet expert John Bortle, the January comet was the third brightest (the two brighter comets appeared in 1965 and 1927). Among the brightest comets of the 20th century, my favorites include Hale-Bopp (1997), Hyakutake (1996), West (1976), and Bennett (1970). Honorable mention goes to Halley (1986), Kahoutek (1973), and to one not on the list, IRAS-Araki-Alcock (1983). So far in this century, the best comet I've seen has been Comet McNaught (2007), the brightest comet in more than 40 years. Apparently, it was even brighter than the Great January Comet of 1910. Unfortunately, by the time it reached its peak brightness, the Great Comet of 2007 was no longer visible from our northern latitude.