Quadrantids

Observing

The Quadrantid meteor shower is one of the strongest meteor showers of the year, but observers can be disappointed if conditions are not just right. The point from where the Quadrantid meteors appear to radiate is located within the extinct constellation Quadrans Muralis. On modern star charts, this radiant is located where the constellations Hercules, Boötes, and Draco meet in the sky. The shower can appear almost nonexistent until about 11 p.m. Unfortunately, the radiant does not attain a very high altitude for most Northern Hemisphere observers before morning twilight puts an end to the show. The best observations are actually possible from countries with high northern latitudes, such as Canada, Finland, Sweden, and Norway. The display is virtually nonexistent for observers in the Southern Hemisphere.

The Quadrantids generally begin on December 28 and end on January 7, with maximum generally occurring during the morning hours of January 3/4. The Quadrantids are barely detectable on the beginning and ending dates, but observers in the Northern Hemisphere can see from 10 to around 60 meteors per hour at maximum. The maximum only lasts for a few hours.

There are other, weaker meteor showers going on around the same time as the Quadrantids. The Quadrantids are medium-paced when compared to meteors from other meteor showers. When you see a meteor, mentally trace it backwards. If you end up where Hercules, Boötes, and Draco meet in the sky then you have probably seen a Quadrantid meteor! If you are not sure where the Quadrantid radiant is in the sky, the following chart will help you find it from the Northern Hemisphere:

Location of the Quadrantids
For Northern Hemisphere Observers

This represents the view from mid-northern latitudes at about 1:00 a.m. local time around January 4. The graphic does not represent the view at the time of maximum, but is simply meant to help prospective observers to find the radiant location. The red line across the bottom of the image represents the horizon. (Image produced by the Author using SkyChart III and Adobe Photoshop.)

History

The first observation of the Quadrantids seems to have occurred on the morning of 1825 January 2, when Antonio Brucalassi (Italy) remarked that "the atmosphere was traversed by a multitude of the luminous bodies known by the name of falling stars." Apparently accidental rediscoveries were also made on 1835 January 2, by Louis Francois Wartmann (Switzerland), and on 1838 January 2, by M. Reynier (Switzerland).

First mention that early January activity might be annual came in 1839, when Adolphe Quetelet (Brussels Observatory, Belgium) and Edward C. Herrick (Connecticut) independently made the suggestion. The meteor shower became known as the Quadrantids because of its emanation from a now obsolete constellation called Quadrans Muralis (the Mural Quadrant) located on some 19th-century star atlases near the point of meeting between Hercules, Boötes and Draco.

Few details were published about this meteor shower during the first couple of decades following its discovery. The first major useful observation of this shower came in 1863, when Stillman Masterman (USA) determined the position of the place from which the meteors appeared to emanate for the very first time. The following year, Alexander Stewart Herschel (England) was met with the unusually high rate of 60 meteors per hour at a time when the radiant was at an average height of only 19°! Although Herschel's high hourly rate did not become an annual event, it did help to stimulate interest in the shower in the years that followed.

Observations of this meteor shower since 1864 have revealed that activity generally spans the period of December 28 to January 7. The Quadrantids are particularly noteworthy because of their very sharp rise to maximum activity around the time of January 3/4. Using records published by the British Astronomical Association (BAA), the British Meteor Society (BMS), and the American Meteor Society (AMS), the Author found that rates are below ten per hour just one day before and after the peak of shower activity. Furthermore, the rise and decline of the shower activity before and after January 3/4 tends to be more gradual and this apparently confirms the frequently held suspicion that this stream is made up of both diffuse and a compact components.

The Quadrantids have not been consistently studied by visual observers. It is too far north to be reasonably studied by observers in the Southern Hemisphere and cold weather prevalent in northern latitudes tends to be a deterrent. Another factor has been the very sharp period of maximum for the shower, which frequently causes even the most diligent of observers to miss the activity only because they are in the wrong location on Earth. A final factor is related to the general faintness of this shower's meteors, thus requiring exceptional observing conditions for the main activity of the shower to be noted. It is probably due to a combination of these factors that has caused a large apparent fluctuation in the hourly rates. During the period spanning 1965 to 1971, members of the BAA observed rates as low as 65 per hour and as high as 190 per hour, while members of the Nippon Meteor Society determined a rate of 101 per hour in 1975. Of course, another probable factor in the variation in hourly rates from one year to the next may be the planet Jupiter.

The planet Jupiter plays a significant role in this meteor stream's evolution. The first indication of this came in 1918, when W. F. Denning and Mrs. Fiammetta Wilson (England) noted their surprise to find the main radiant to be about eight degrees north of the "normal" radiant. They stated that a more northerly radiant had been suspected in January 1916 and 1917, "but the data at the time were regarded as insufficient." Independent confirmations of the 1918 radiant came from several other observers in England and it was noted that a weak shower actually did occur from the normal radiant as well. This type of alteration represents a short-term alteration of the orbit by Jupiter.

The long-term effect of Jupiter on the Quadrantid stream was first investigated by S. E. Hamid and M. N. Youssef in 1963. They took the orbits of six Quadrantid meteors that were photographed in 1954 and applied perturbations by Jupiter for the past 5000 years. While the Quadrantid orbit passes as close as 92 million miles from the sun now, they noted the orbit was significantly different 1500 years ago, when the orbit passed as close as 10 million miles from the sun. Interestingly, about 4000 years ago, the orbit was very similar to today's orbit. The authors speculated that the stream's parent comet was captured by Jupiter about 4000 years ago and shortly thereafter it developed meteors along its path. "Because an appreciable number of these meteors, which now form the Quadrantids, did not suffer another close approach to Jupiter, the shower is observed to be compact." Interestingly, Hamid and F. L. Whipple noted later in 1963 that the Quadrantid orbit was very similar to that of the Delta Aquarids about 1300-1400 years ago. They added, "the physical characteristics of the meteoroids belonging to the two streams appear to be similar, as judged by their light curves." During 1979, Iwan P. Williams, Carl D. Murray and David W. Hughes essentially confirmed the results of Hamid and Youssef, but looked at the future evolution of the orbit. They noted that Jupiter would eventually alter the orbit so that it would no longer intersect the Earth's orbit. They predicted that the Quadrantids would no longer be visible by the year 2400.