:''For Giovanni Bianchini (1410-ca. 1449), see
Giovanni Bianchini.''
'Francesco Bianchini' (
December 13,
1662 –
March 2,
1729) was an
Italian philosopher and
scientist. He worked for the
curia of three
popes, including being camiere d`honore of Clement XI, and secretary of the commission for the reform of the
calendar, working on the method to calculate the astronomically correct date for
Easter in a given year.

A
gnomon in the south wall of the Santa Maria degli Angeli e dei Martiri projects the sun's image onto Bianchini's line every solar noon
He published many books, including ''La Istoria universale'', and ''Hesperi et Phosphori nova Phaenomena'' in which he deduced a rotational period from the observation of the surface of
Venus. Today, we know that this is impossible, because of the thick cloud cover on this
planet. He also worked on the
parallax of Venus, and he measured the precession of the
Earth's rotational axis.
As part of his efforts to improve the accuracy of the calendar, Bianchini constructed an important meridian line in the basilica of
Santa Maria degli Angeli e dei Martiri in
Rome, a device for calculating the position of the sun and stars.
His point of view on the
Copernican system is not evident, but it was noted that the picture of the planetary system in his book about Venus has an empty center.
Craters on
Mars and the
Moon were named in his honor.