FIG. 1 a, Timing residuals for PSR1718-19, obtained assuming the simple slowdown model given in Table 1, plotted as a function of orbital phase.

There is also a possibility of detecting brightness variations as a function of orbital phase if the sub-pulsar point of the companion star is illuminated by high energy pulsar radiation.

Such an effect is seen in PSR B1957+20, where the companion star varies in brightness with orbital phase by about three magnitudes.

In 1639, Giovanni was the first person to discover that the planet Mercury had orbital phases, like those of the Moon and Venus.

The third panel of the figure shows the projection on the plane of the sky (i.e. the system as we see it) at different orbital phases.

In graphical representations of orbitals, orbital phase is depicted either by a plus or minus sign (which has no relationship to electric charge) or by shading one lobe.

In 1639 Giovanni Zupi used a telescope to discover that the planet had orbital phases similar to Venus and the Moon.

The most remarkable resonance involving Io-Europa-Ganymede includes the following relation locking the orbital phase of the moons:

The Posleen lose some of their efficiency when the targets get into orbital phase.

Giovanni Battista Zupi observes that the planet Mercury has orbital phases.