Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

Could a tidally locked planet have seasons?

According to my understanding, a tidally locked planet rotates around itself exactly once per rotation around its sun. However, if the axis of rotation of the planet is significantly off from the axis of rotation around the sun, wouldn't it still have seasons?

Or does tidal locking require that the axis of rotation of the planet about itself be perfectly orthogonal to the axis of rotation of the planet about its sun?

If not, what would happen to a "tidally locked" planet with an axis of rotation "pointing towards" its sun (sort of like Uranus)?

share|improve this question

1 Answer 1

up vote 4 down vote accepted

I'm not a expert in this area, but I think the mechanism of tidal locking works better when the rotation axis is aligned or nearly aligned with the orbital axis than it does under other circumstances.

But if you had a planet for which the day equaled the year but for which the rotation inclination was non-trivial it would experience seasons from it's inclination.


In addition, any tidally locked planet with non-trivial orbital eccentricity would have seasons owing to differing distances from the primary.

Such seasons would differ a bit from the ones that we are used to because

  1. they would come uniformly to the whole globe instead of the northern and southern hemispheres being out of phase
  2. the winter would be longer than the summer on account of Kepler's laws

(Non-tidally locked planets with eccentric orbits also experience this effect. Earth's current orbital eccentricity is about 0.017 meaning that there is about a 6.8% variation in the energy received from the sun over the course of the year.)

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.