The grand conclave: one of the greatest celestial events was seen by only a few.
JANUARY 2014 MARKS the 30th anniversary of perhaps the most remarkable celestial planetary convergence in modern times. Throughout January 1984 an observer could, in principle, observe all of the planets (including Pluto) within the same naked-eye field of view. But what could have been among the most memorable skygazing events went largely unnoticed, especially by the general public. As such, it seems that only a widely observed event is regarded as a "great" event in astronomical history.
The foundation for the 1984 planetary grouping was laid in the 1970s when Uranus, Neptune, and Pluto convened and awaited the arrival of Jupiter and Saturn in the early 1980s. Of course, the inner planets continued numerous laps around the Sun during that decade, but it took Mars to seal the deal in the fall of 1983 when it moved into the quadrant already shared by the outer planets. Luckily, Earth was situated about 90[degrees] (heliocentric longitude) away from its companions in December 1983, thus setting up the grandstand view to come.
Although several fine planetary groupings occurred during this period, none could match the January 1984 "grand conclave," as Robert C. Victor described it in that month's issue of S&T (page 58). By January 1st, seven planets had gathered between Virgo and Sagittarius. On January 10th, a Mercury-Neptune-Jupiter conjunction had formed just east of a Venus-Uranus pairing. Mars arrived in Virgo around January 12th, creating an 8-planet array spanning less than 60[degrees] of ecliptic longitude. In fact, January 12th through 15th marked the tightest bunching of the planets for the past several centuries.
If this weren't enough, the waning crescent Moon entered the area and pulled to within 1[degrees] of Saturn on January 26th. A tight Jupiter-Venus-Neptune conjunction had already formed in Ophiuchus, with Venus and Jupiter separated by less than 1[degrees] and Venus-Neptune separated by less than 1 arcminute.
In his book The Starry Room: Naked-Eye Astronomy In The Intimate Universe, S&T contributing editor Fred Schaaf recalls the bitter cold morning of January 26th, when he stepped out of his New Jersey home to observe the Conclave: "This morning, the ultimate dream of a planet watcher was come true: all of the planets condensed before me into one straight-forward, nowhere peripheral view. It struck me like nine-branched lightning, held me still as a (deeply breathing) statue. All the planets at once."
The 1984 Grand Conclave could have drawn an outpouring of public interest and given a major boost to popular astronomy. Alas, for Northern Hemisphere observers the gathering took place in the pre-dawn hours of the coldest winter month, the worst possible time for public outreach. Still, the Conclave deserves membership in astronomy's pantheon of historic events, along with the Crab supernova of 1054, the Leonid Meteor Storm of 1833, this year's Chelyabinsk fireball, and others. What remarkable celestial events are likewise missing from the history books because they were observed by only a few?
Eric Fischer has been an avid backyard observer for 50 years and an active member of the Amateur Astronomers Association of Pittsburgh, serving three terms as president.