I'll try to be extra good today.
Some details about this feastday:
The origin of this Feast is sought in Palestine. It goes back to the consecration of a church in Jerusalem, which tradition identifies as that of the present basilica of St. Ann.
At Rome the Feast began to be kept toward the end of the 7th century, brought there by Eastern monks. Gradually and in varied ways it spread to the other parts of the West in the centuries that followed. From the 13th century on, the celebration assumed notable importance, becoming a Solemnity with a major Octave and preceded by a Vigil calling for a fast. The Octave was reduced to a simple one during the reform of St. Pius X and was abolished altogether under the reform of Pius XII in 1955.
The present Calendar characterizes the Birth of Mary as a "Feast," placing it on the same plane as the Visitation.
For some centuries now, the Birth has been assigned to September 8 both in the East and in the West, but in ancient times it was celebrated on different dates from place to place. However, when the Feast of the Immaculate Conception (which has a later origin than that of the Birth) was extended to the whole Church, the Birth little by little became assigned everywhere to September 8: nine months after the Solemnity of the Immaculate Conception.
And as to the painting above, it is "Madonna dell Granduca" by Raphael. It is by far one of my favorite representations. A bit about it, from the Wikipedia:
The Madonna del Granduca is a painting by the Italian renaissance artist Raphael. It was probably painted in 1505, shortly after Raphael had arrived in Florence. The influence of Leonardo da Vinci, whose works he got to know there, can be seen in the use of sfumato. The painting belonged to Ferdinand III, Grand Duke of Tuscany, from whom it got its name.
Sfumato, by the way, is a painting technique achieved by layering translucent colors to achieve an effect of depth.
Some more about the painting from "The Story of Art":
A painting like Raphael's 'Madonna dell Granduca', is truly 'classical' in the sense that it has served countless generations as a standard of perfection in the same way as the works of Pheidias and Praxiteles. It needs no explanation. In this respect it is indeed 'obvious'. But, if we compare it with the countless representations of the same theme which preceded it, we feel that they have all been groping for the very simplicity that Raphael has attained.