The death of Herr Kirch, which took place in 1710, caused no interruption in Frau Kirch's astronomical occupations. Among the evidences of her activity is a work which she wrote in 1713 on the conjunction of Jupiter and Saturn in the year following. In our day the conjunction of planets is for the laity a mere matter of curiosity, while for professional astronomers it is quite devoid of particular interest. But it was not so in the time of Maria Kirch, for then astronomy was so intimately associated with astrology that mankind attributed to such special positions of the planets a certain occult and capricious influence on the destiny of the earth and its inhabitants. As theoretical astronomy progressed, such erroneous notions were abandoned, because it was then recognized that the conjunction of the superior planets was not something fortuitous, but something that was reproduced at fixed periods by the known movements of these bodies. Writers on the subject made it a point to warn the public that they had nothing in common with astrologers. Among these was Christopher Thurm, who published a work on the conjunction of Jupiter and Saturn in 1681. Similarly, the book of Maria Kirch contains only astronomical calculations and nothing more--a fact that redounds to the honor of the author and to the age in which she lived. The daughters of Maria Kirch, even long after their mother's death, continued to occupy themselves with astronomy. They calculated for the Berlin Academy of Sciences its _Almanac_ and _Ephemeris_, which were among the sources of revenue of this learned body. During the same period a number of French and Italian astronomers had female collaborators in their own families. Celsus, the celebrated professor of Upsala, and a pupil of the son of Gottfried Kirch, had been accorded a most cordial reception, while passing through Paris on his way to Bologna, by De L'Isle who had a sister who was devoted to astronomy. On his arrival in Italy he found that his new master, the director of the observatory at Bologna, had two sisters, Teresa and Maddalena, both of great learning, who, like their brother, were engaged in the study of the heavens and collaborated with him in the preparation of the _Ephemeris_ of Bologna. This caused Celsus, in a letter to Kirch, to declare "I begin to believe that it is the destiny of all the astronomers whom I have had the honor of becoming acquainted with during my journey to have learned sisters. I have also a sister, although not a very learned one. To preserve the harmony, we must make an astronomer of her."[139]