Before the sun rises a dark purple hued band appears above the western horizon ending in wedges to north and south. This is the shadow of the planet cast through its own atmosphere. A rosy pink glow suffuses the upper edge - the Belt of Venus or Anti-twilight Arch.
As sunrise approaches the shadow sinks but becomes more distinct.
The shadow is marks the unlit atmosphere masked from the sun's rays by the Earth's rim.
The shadow’s upper edge is where the sun is just rising. There, the light of the new sun travels long through the air and is most reddened by Rayleigh scattering. The direct reddened rays combine with scattered blue light from the sunlit air above to paint the pinks of the Belt of Venus.
For those of us now in winter, the late dawns are good opportunities to see the shadow in the west before sunrise and breakfast.