Figure 2-10 The Changing Appearance of Venus This figure shows how the appearance (phase) of Venus changes as it moves along its orbit. The number below each view is the angular diameter (d) of the planet as seen from Earth, in arcseconds. The ″ indicates arcseconds, as introduced in An Astronomer’s Toolbox 1-1: Observational Measurements Using Angles. Note that the phases correlate with the planet’s angular size and its angular distance from the Sun, both as seen from Earth. These observations clearly support the idea that Venus orbits the Sun.