Sky & Telescope January 1982 [antikvár]

gle of the narrowest sector are also cited. The dates are based on Ephemeris time, which differs by less than three hours from Universal time during the period considered. Before 1583 the Julian calendar has been used. Values in the fourth and sixth columns have been rounded to the nearest integer. In a.d. 2492 and 2520, the angle of the minimum sector will be between 89° 30' and 90° 00'.When a planetary sector is a minimum, it is limited at one side by two planets (at the moment one is overtaking the other), and at the other side by one planet. For each of the sectors in the table, the next to last column contains abbreviated names of the three "limiting" planets. It should be further noted that, at the time of the smallest sector, neither Mercury (the fastest planet) nor Neptune (the slowest) can be alone at one end of the sector.We see from the table that sometimes there is no planetary quadrant during more than 300 years, for example between 1307 and 1666 and presently from 1817 until 2161. On the other hand, there may be more than one quadrant in the same century, such as four during the 12th.The case of a.d. 408 is borderline; the narrowest sector I found was 90° 01'. However, it's not certain whether an accuracy of one arc minute can be obtained for such a remote epoch with the theory I used for the motions of Uranus and, especially, Neptune.The smallest sector during the whole period occurred on April 11, 1128, when the eight planets were within a heliocentric sector of only 40°. Another vety small sector (46°) occurred April 14, 1307. The corre-ATo Vernal Equinox ISUNPlanetary Sector April 11, 1128The smallest planetary sector in the three millennia studied by J. Meeus. Abbreviations (first two letters of each planet's name) are the same as in the table; the orbits are not to scale.spending planetary quadrant had a duration of 51 days. The longest possible is 55 days (with present values of the eccentricities of the planetary orbits), and it takes place when all the planets are aligned at the longitude of Mercury's aphelion.Pluto. A calculation gave me approximate positions of Pluto for each of the 25 cases. In the last column of the table a