Why does the Gaia color-magnitude diagram have this shape? I was looking at the visualization tools of Gaia, and tried plotting a color-magnitude diagram. On the right hand side of the image, photGMeanMag (mag) (the amount of light) is plotted as a function of BpRp (mag) (the color). 



I was surprised by the distribution of the points in the plot, since I was expecting to see something like the main sequence of the HR diagram, like in this plot: 



Why are the points distributed in a sort of wedge, rather than along a diagonal line?
Try plotting absolute G magnitude (i.e. corrected for the fact tthat all the stars are at different distances) on the y-axis.