An earth sized planet in the habitable zone between two stars has no moon (and even if it has, it is not significant to the story) and is tidally locked to star A but not star B. Can it still have a solar eclipse w.r.t A getting eclipsed (possibly by B)

The side of planet facing A is aa. The side facing away from A is bb.

Star A is bigger than B and B is too far away to sufficiently heat up the side bb. So

(1) what happens to aa on the day of the eclipse? Does it become as cold as bb? (2) does the wind pattern change on the day of the eclipse with both sides going cold? (3) can only A be eclipsed and B not ever be eclipsed?

Edit: will it be possible to have A eclipsed if B is not farther away but much smaller?


1 Answer 1


Based on your description of the system, A will never be eclipsed, because the other star B is much further away, therefore it can never be in the optical path between A and the planet.

What might happen is that A periodically covers B, but since B is far and doesn't significantly heat the planet, it will have no significant effect on it.

  • $\begingroup$ in that case, if I make B closer but smaller than A to not heat up bb side , can this condition happen then? What about the questions I have raised in that case? $\endgroup$
    – mukul215
    Commented Jul 6, 2021 at 8:59
  • $\begingroup$ Dutch is right - if planet is tidally locked to A, B will never come between A and the planet. If it did, B would be closer to the planet than A and would capture the planet or at least disrupt its orbit of A.. You could place B very close to A and the planet out at some distance, orbiting the barycenter of both stars. Then B would sometimes eclipse A and vice versa. $\endgroup$
    – Willk
    Commented Jul 6, 2021 at 16:04
  • $\begingroup$ @willk, in that case, would the planet be tidally locked around A only and not B? I am sorry I am unable to find an answer to that despite studying about such systems on the net. $\endgroup$
    – mukul215
    Commented Jul 6, 2021 at 16:11
  • $\begingroup$ @mukul215 : A tidally locked planet keeps one face towards what it is orbiting. It seems to me that a planet could be tidally locked towards the barycenter of a binary star pair that the planet is orbiting. $\endgroup$
    – Willk
    Commented Jul 9, 2021 at 2:16
  • $\begingroup$ @willk , so in that case it won't have a permanent day or night side, no? Maybe something in between? $\endgroup$
    – mukul215
    Commented Jul 9, 2021 at 3:31

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