Every object that is not a star is visible only when a star's light shines on it. Then, some of the star's light may be reflected from the object, to our eyes.
Objects that do not generate light, and are visible only when illuminated by a star's light, include planets, moons, comets, asteroids, meteoroids, and artificial satellites without batteries and headlights.
Since the velocity of the object is the derivative of the position graph, the area under the line in the velocity vs. time graph is the displacement of the object.
