The Brazilian flag was adopted on November 19, 1889. It is based on a green rectangle with proportions of 7:10.
Enclosed to it is a yellow rhombus, which inscribes a blue circle, crossed by a white sign with the words "ORDER AND PROGRESS" written in green letters, as well as 27 white stars.
In the blue circle of the national flag, each state of the federation, as well as the Federal District, is represented by a star.
So there are 27 stars from 8 constellations representing the current 26 states and the Brazilian federal district, as shown in the figure below.
Meaning of the stars (click to enlarge)