Because of the irregularity of the dimming. A normal planet should dim the star in a consistent predictable pattern, such as once an orbit and the orbit should

Because of the irregularity of the dimming. A normal planet should dim the star in a consistent predictable pattern, such as once an orbit and the orbit should take the same time each time. Something like _ _ A _ _ A _ _ A _ _ A Multiple planets should do the same, the nearer planets dim it more often, the farther less often, but the same time between the same planet's occultation and a predictable pattern. Something like _A _ _ B A _ _ _ A _ _ B A _ _ _ A _ _ B A