January's chilly meteors
Updated: June 18th, 2018
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Right: Artist Duane Hilton's concept of a Quadrantid fireball streaking through the moonlit sky above the White Mountain Range in central California.
The shower stretches from Dec. 28, 1998 to Jan. 7, 1999, with a sharp maximum on Jan. 3 when as many as 100 shooting stars per hour are expected. The nearly full moon during the shower's peak will make most meteors difficult to see, but shooting stars brighter than magnitude 3 should be visible if the moon is the only source of light pollution.
Despite the fact that the Quadrantids make up one of the year's most intense meteor showers, they are also among the least observed. Why? One reason is the weather. The shower's radiant is located high in the Northern sky, so the Quadrantids are visible mainly to observers in the Northern hemisphere where the weather is cold and often stormy in January. After a series of autumnal and early winter meteor showers like the Giacobinids, Leonids, and Geminids, many sky watchers have seen plenty of meteors by the time the Quadrantids arrive. Who can blame them for lingering by the comforts of the hearth while the shower rages outside?
The situation is almost certainly exacerbated by the brevity of the shower's peak, which usually lasts just a few hours. Even dedicated meteor observers are likely to miss such a sharp maximum simply because they live at the wrong longitude. In his classic book Meteor Astronomy, Prof. A.C.B. Lovell lamented that "useful counts of the Quadrantid rate were made in 24 Januaries out of a possible 68 between 1860 and 1927. ... The maximum rate during this period appears to have occurred in 1932 (80 per hour) although the results are influenced by unfavorable weather." With observations in such short supply, it's no wonder that many basic questions about the Quadrantids remain unanswered. For example, What is the source of the Quadrantid meteors? No one knows.
Most meteor showers are caused by comets. When a comet passes close to the sun, bits of dust and ice boil away from its nucleus and form a stream of tiny particles, called meteoroids, that orbit the sun. A meteor shower results when Earth passes through the debris stream.
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Presumably the Quadrantid meteors are formed in the same way. But when astronomers compare the orbits of Quadrantid meteoroids with the orbits of all known comets and asteroids, they can't find a match. The source of the Quadrantid meteor shower is unknown.
Quadrantid meteroids are in a highly elliptical orbit tilted about 70 degrees from the plane of the solar system. Some astronomers have speculated that the parent comet was captured or disrupted by Jupiter's gravity thousands of years ago, and that the Quadrantid meteoroids are the leftovers from that ancient celestial collision. Advocates of this idea believe that the original comet was orbiting the Sun nearly in the plane of the solar system. Since its disruption, the orbit of the debris stream evolved to its present state because of periodic gravitational perturbations from Jupiter.
Other scientists argue that the source of the Quadrantids could be an existing comet or asteroid that has yet to be discovered. If this is true, then we might expect to see outbursts of Quadrantid meteors during years when the parent comet is nearby, just as the well-known Leonid meteors are especially intense around the time that their parent comet, Tempel-Tuttle, passes close to Earth. In this regard, amateur observations of the Quadrantids could prove especially valuable to professional astronomers who would like to know when to look for the source of the meteors.